Document and Entity Information Statement [Table] Statement [Line Items] Statement Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Current Reporting Status Entity Filer Category Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Condensed Consolidated Balance Sheets Assets [Abstract] Assets Assets, Current [Abstract] Current assets: Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Cash and cash equivalents at beginning of period Cash and cash equivalents Available-for-sale Securities, Current Marketable securities Prepaid Expense and Other Assets, Current Prepaid expenses and other current assets Assets, Current Total current assets Property, Plant and Equipment, Net Property and equipment, net Assets Total assets Liabilities and Equity [Abstract] Liabilities and Stockholders' Equity Liabilities, Current [Abstract] Current liabilities: Accounts Payable, Current Accounts payable Accrued Liabilities, Current Accrued expenses Liabilities, Current Total current liabilities Liabilities Total liabilities Stockholders' Equity Attributable to Parent [Abstract] Stockholders' equity: Preferred Stock, Value, Issued Preferred stock, par value $0.0001 per share authorized: 5,000,000 shares at September 30, 2017 and December 31, 2016; 1,969,797 and no shares issued and outstanding at September 30, 2017 and December 31, 2016, respectively Common Stock, Value, Issued Common stock, par value $0.0001 per share authorized: 200,000,000 at September 30, 2017 and December 31, 2016, respectively; 12,495,705 and 11,951,866 shares issued and outstanding at September 30, 2017 and December 31, 2016, respectively Additional Paid in Capital, Common Stock Additional paid-in-capital Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income Retained Earnings (Accumulated Deficit) Accumulated deficit Stockholders' Equity Attributable to Parent Total stockholders' equity Liabilities and Equity Total liabilities and stockholders' equity Preferred Stock, Par or Stated Value Per Share Preferred stock, par value (in dollars per share) Preferred Stock, Shares Authorized Preferred stock, shares authorized Preferred Stock, Shares Issued Preferred stock, shares issued Preferred Stock, Shares Outstanding Preferred stock, shares outstanding Common Stock, Par or Stated Value Per Share Common stock, par value (in dollars per share) Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares, Issued Common stock, shares issued Common stock received Common Stock, Shares, Outstanding Common stock, shares outstanding Shares outstanding Condensed Consolidated Statements of Operations Costs and Expenses [Abstract] Operating expenses: Research and Development Expense (Excluding Acquired in Process Cost) Research and development General and Administrative Expense General and administrative Operating Expenses Total operating expenses Operating Income (Loss) Loss from operations Interest Expense Interest expense Interest Income, Operating Interest income Other Income Other income Net Income (Loss) Available to Common Stockholders, Basic Net loss Net loss Net Loss Earnings Per Share [Abstract] Net loss per common share: Earnings Per Share, Basic and Diluted Basic and diluted net loss per common share (in dollars per share) Weighted Average Number of Shares Outstanding, Basic and Diluted Basic and diluted weighted average number of common shares outstanding Condensed Consolidated Statements of Comprehensive Loss Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Other comprehensive income (loss): Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent Unrealized gain (loss) on available-for-sale securities Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive loss Condensed Consolidated Statements of Cash Flows Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Cash flows from operating activities: Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net loss Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net loss to net cash used in operating activities: Interest on related party debt paid other than in cash for example by issuing additional debt securities. As a noncash item, it is added to net income when calculating cash provided by or used in operations using the indirect method. Paid-in-Kind Interest, Related Party Debt PIK interest expense on convertible promissory notes payable - related parties Share-based Compensation Stock-based compensation expense Depreciation, Depletion and Amortization Depreciation and amortization expense Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: Increase (Decrease) in Accounts Receivable, Related Parties Accounts receivable - related parties Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses and other current assets Increase (Decrease) in Accounts Payable, Trade Accounts payable Increase (Decrease) in Accrued Liabilities Accrued expense The increase (decrease) during the reporting period in the accrued interest payable to related party disclosed in the statement of cash flows. Increase Decrease In Accrued Interest Related Party Accrued interest - related party Net Cash Provided by (Used in) Operating Activities, Continuing Operations Net cash used in operating activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Cash flows from investing activities: Proceeds from Divestiture of Businesses Cash received from merger transaction Payments to Acquire Available-for-sale Securities Purchases of marketable securities Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities Sales and maturities of marketable securities Payments to Acquire Property, Plant, and Equipment Purchases of property and equipment Amount of cash inflow for the sale of long-lived, physical assets used to produce goods and services and not intended for resale and other assets. Proceeds from Sale of Property, Plant, and Equipment And Other Assets Net proceeds from the sale of property, equipment and other assets Net Cash Provided by (Used in) Investing Activities, Continuing Operations Net cash provided (used) in investing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Cash flows from financing activities: Proceeds from Issuance of Common Stock Proceeds from issuance of common stock, net of transaction costs Net proceeds after deducting commissions and other transactions costs Proceeds from Related Party Debt Cash received Proceeds from convertible notes - related parties Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net cash provided by financing activities Net Cash Provided by (Used in) Continuing Operations Net increase (decrease) in cash and cash equivalents Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Supplemental disclosure of cash flow information: The value of financial instruments that the original debt payable to related party is being converted into in a non cash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. Related Party Transactions, Debt Conversion Converted Instrument Amount Exchange of related party advances payable for convertible notes Conversion amount The value of related party debt restructured in non-cash investing or financing transactions. Restructuring Of Related Party Debt Related party debt restructuring Organization, Business and Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Organization, Business and Basis of Presentation Summary of Significant Accounting Policies Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Summary of Significant Accounting Policies Reverse Merger Business Combination Disclosure [Text Block] Reverse Merger Liquidity And Uncertainties Disclosure Abstract Liquidity and Uncertainties Substantial Doubt about Going Concern [Text Block] Liquidity and Uncertainties Cash, Cash Equivalents and Marketable Securities Cash, Cash Equivalents, and Marketable Securities [Text Block] Cash, Cash Equivalents and Marketable Securities N/A Convertible Promissory Notes - Related Parties The entire disclosure of convertible promissory notes related parties. Convertible Promissory Notes Related Parties Disclosure [Text Block] Convertible Promissory Notes - Related Parties Stockholders' Equity (Deficit) Stockholders' Equity Note Disclosure [Text Block] Stockholders' Equity (Deficit) Stock-based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Stock-based Compensation Related Party Transactions Related Party Transactions Disclosure [Text Block] Related Party Transactions Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Use of Estimates, Policy [Policy Text Block] Use of Estimates Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents Marketable Securities, Policy [Policy Text Block] Marketable Securities Fair Value of Financial Instruments, Policy [Policy Text Block] Fair Value of Financial Instruments Research and Development Expense, Policy [Policy Text Block] Research and Development Costs Disclosure of accounting policy for patents. Patents [Policy Text Block] Patents Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Stock-Based Compensation Income Tax, Policy [Policy Text Block] Income Taxes Earnings Per Share, Policy [Policy Text Block] Basic and Diluted Loss Per Common Share New Accounting Pronouncements, Policy [Policy Text Block] Recent Accounting Pronouncements Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Summary of the outstanding securities not included in the computation of diluted net loss per common share as their inclusion would be anti-dilutive Cash, Cash Equivalents and Investments [Table Text Block] Summary of cash, cash equivalents and available-for-sale marketable securities Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of stock option activity Schedule of Nonvested Restricted Stock Units Activity [Table Text Block] Summary of unvested restricted share activity Tabular disclosure of the allocation of equity-based compensation costs to a given line item on the income statement for the period. This may include the amount of total share-based compensation cost, including the amounts attributable to each share-based compensation plan and any related tax benefits. It includes the reporting line for the costs expensed. Schedule of Share Based Compensation Expense Allocation of Compensation Costs and Recognized Period Costs [Table Text Block] Schedule of stock-based compensation expense Schedule of Unrecognized Compensation Cost, Nonvested Awards [Table Text Block] Schedule of unrecognized stock-based compensation expense Income Taxes Income Taxes The percentage of valuation allowance on the deferred tax assets. Deferred Tax Assets, Percentage Of Valuation Allowance Valuation allowance on deferred tax assets (as a percent) Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities Name [Domain] Antidilutive Securities, Name [Domain] An arrangement whereby an employee or member of the Board of Directors is entitled to receive in the future, subject to vesting and other restrictions, a number of shares in the entity at a specified price, as defined in the agreement. Employee And Directors Stock Options [Member] Stock options Restricted Stock [Member] Restricted stock Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Anti-dilutive securities Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Outstanding securities not included in the computation of diluted net loss per common share as their inclusion would be anti-dilutive (in shares) Schedule of Business Acquisitions, by Acquisition [Table] Legal Entity [Axis] Entity [Domain] Entity [Domain] Parent Company [Member] Synta Pharmaceuticals Corp Business Acquisition [Axis] Business Acquisition Acquiree [Domain] Business Acquisition, Acquiree [Domain] Represents information pertaining to merged company. Merger Combined Company [Member] Merged Company Business Acquisition [Line Items] Reverse Merger Reverse Merger Agreement Abstract Reverse Merger Agreement [Abstract] Reverse Merger The number of shares issued by the entity for each share of the acquired entity. Number Of Shares Issued For Each Share Of The Acquired Entity Number of shares issued for each share of private Madrigal stock Conversion of Stock, Shares Converted Preferred stock conversion ratio Common stock converted Business Acquisition, Percentage of Voting Interests Acquired Voting interest acquired Stockholders' Equity, Reverse Stock Split Reverse stock split Represents shares received by plan participants of bonus Or share-based compensation plan in business combination. Business Combination, Change Control Shares Received by Plan Participants In Bonus Or Share Based Compensation Plan Shares received by plan participants in Change in Control Bonus Plan Percentage of awards received by plan participants to the total shares of the entity. Bonus Plan Awards, Percentage Of Awards Received To Entitys Shares Percentage of change in control bonus plan awards to total common shares outstanding Allocated Share-based Compensation Expense Stock-based compensation expense Schedule of Investments [Table] Major Types of Debt and Equity Securities [Axis] Major Types Of Debt And Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Corporate Debt Securities [Member] Corporate debt securities due within 1 year of date of purchase Debt securities due within 3 months issued by domestic or foreign corporate business, banks and other entities with a promise of repayment. Corporate Debt Securities2 [Member] Corporate debt securities due within 3 months of date of purchase Measurement Basis [Axis] Portion At Fair Value Fair Value Disclosure [Member] Portion at Fair Value Measurement [Member] Carrying Reported Amount Fair Value Disclosure [Member] Carrying value Estimate Of Fair Value Fair Value Disclosure [Member] Fair value Fair Value, Hierarchy [Axis] Fair Value Measurements Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Fair Value Inputs Level1 [Member] Level 1 Fair Value Inputs Level2 [Member] Level 2 Schedule of Investments [Line Items] Cash, Cash Equivalents and Marketable Securities Cash and Cash Equivalents, Fair Value Disclosure Cash and cash equivalents Represents the maturity period from date of purchase to classify an investment as marketable securities. Maturity Period from Date of Purchase to Classify Investment as Marketable Securities Maturity period from date of purchase to classify an investment as marketable securities Available-for-sale Securities, Amortized Cost Basis Marketable securities, cost Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Marketable securities, unrealized gains Available-for-sale Securities Marketable securities, fair value This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings, and cash and cash equivalents. Cash, Cash Equivalents, and Short-term Investments, At Cost Total cash, cash equivalents and marketable securities, Cost This item represents the gross unrealized gains for cash and cash equivalents securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities. Cash and Cash Equivalents and Available for Sale Securities, Gross Unrealized Gains Total cash, cash equivalents and marketable securities, Unrealized gains Cash, Cash Equivalents, and Short-term Investments Total cash, cash equivalents and marketable securities, Fair value Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction, Rate Interest rate The amount of interest payable and waived interest due to related party. Interest Payable And Waived Interest Related Party Current Total accrued and waived interest The amount of interest payable due to related party. Interest Payable Related Party Current Accrued interest The amount of interest payable waived due to related party. Interest Payable Waived Related Party Current Net waived interest recorded as an increase to APIC The number of lenders that exchange advances payable to convertible debt. Related Party Lender Exchanged Advances To Convertible Debt, Number Number of lender that exchanged advances payable to convertible debt Schedule of Collaborative Arrangements and Non-collaborative Arrangement Transactions [Table] Counterparty Name [Axis] Repurchase Agreement Counterparty Name [Domain] Counterparty Name [Domain] Represent of Cowen & Co. LLC Member. Cowen Co. Llc [Member] Cowen & Co. LLC Range [Axis] Range [Member] Range [Domain] Maximum [Member] Maximum Type of Arrangement and Non-arrangement Transactions [Axis] Arrangements And Nonarrangement Transactions [Member] Arrangements and Non-arrangement Transactions [Domain] Represents information pertaining to at-the-market issuance sales agreement for the sale of the entity's common shares. At The Market Issuance Sales Agreement [Member] At-The-Market Issuance Sales Agreement Represents information pertaining to private placement offering to sell its securities Securities Purchase Agreement [Member] Purchase Agreement Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] Stockholders' Equity (Deficit) Represents the number of votes per share that common stockholders are entitled to receive. Common Stock Voting Rights Number Number of votes per share that common stockholders are entitled to receive Represents the maximum aggregate offering price the entity may issue and sell shares of its common stock from time to time, at the entity's option, according to at-the-market issuance sales agreement with third party. Common Stock Aggregate Offering Price Maximum aggregate offering price Represents the percentage of gross proceeds payable as commission during the period. Percentage of Gross Proceeds Payable as Commission Percentage of gross proceeds payable as commission Represents number of days of notice period for termination of sales agreement. Sales Agreement Termination Notice Period Days Notice period of termination of sales agreement Stock Issued During Period, Shares, New Issues Number of shares sold by the entity Stock Issued During Period, Value, New Issues Value of shares sold by the entity