License, Collaboration and Other Significant Agreements - Additional Information (Details)							1 Months Ended			3 Months Ended
		Feb. 14, 2020 USD ($)	Apr. 08, 2019 USD ($)	May 12, 2017 USD ($) $ / shares shares	Apr. 25, 2017 USD ($)	Feb. 09, 2017 USD ($) $ / shares shares	Jul. 31, 2019 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($) Obligation shares	Sep. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognized revenue under license agreement											$ 88,478,000		$ 72,666,000
Deferred revenue											77,685,000
Revenue on short-term or current liabilities											34,886,000				$ 39,830,000
Deferred revenue, noncurrent											$ 42,799,000				$ 33,120,000
Common stock shares sold | shares											130,251,440				121,674,568
License, Collaboration and Other Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognized revenue under license agreement											$ 59,269,000		49,555,000
Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable	[1]										84,566,000		29,933,000		$ 15,822,000	$ 1,587,000
Prepaid Expenses and Other Current Assets
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable											546,000
Accrued Expenses and Other Current Liabilities
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue											615,000
Mitsubishi Tanabe Pharma Corporation | License, Collaboration and Other Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognized revenue under license agreement											$ 0		0
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue												$ 10,000,000.0
Collaboration Agreement, expiration period											10 years
Collaboration Agreement, notice period for termination											12 months
Upfront cash payment received											$ 20,000,000.0
Percentage of royalty payments on sales											20.00%
Additional milestone or royalty payments received											$ 0
Number of performance obligations | Obligation											2
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											$ 175,000,000.0
Mitsubishi Tanabe Pharma Corporation | New Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Data access fee receivable																	$ 25,000,000.0
Mitsubishi Tanabe Pharma Corporation | Development And Commercialize Research And License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received											20,000,000.0
Cost of research services											20,500,000
Deferred revenue											0
Accounts receivable											0
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation and Otsuka Pharmaceutical Company Limited | Scenario Forecast
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received										$ 10,400,000
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation and Otsuka Pharmaceutical Company Limited | Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable											10,400,000
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation and Otsuka Pharmaceutical Company Limited | Short-term Deferred Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue on short-term or current liabilities											4,000,000.0
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation and Otsuka Pharmaceutical Company Limited | Other Current Liabilities
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue on short-term or current liabilities											6,400,000
Mitsubishi Tanabe Pharma Corporation | Regulatory Milestone Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue							$ 10,000,000.0
Mitsubishi Tanabe Pharma Corporation | Regulatory Milestone Payments | Development and Commercialize Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue												$ 10,000,000.0
Additional milestone revenue receivable											15,000,000.0
Mitsubishi Tanabe Pharma Corporation | Regulatory Milestone Payments | Development and Commercialize Collaboration Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received											40,000,000.0
Mitsubishi Tanabe Pharma Corporation | Regulatory Milestone Payments | Development And Commercialize Research And License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											10,000,000.0
Mitsubishi Tanabe Pharma Corporation | Development, Regulatory and Commercial Events | Development and Commercialize Collaboration Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											225,000,000.0
Mitsubishi Tanabe Pharma Corporation | Development Milestones | Development and Commercialize Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											10,000,000.0
Mitsubishi Tanabe Pharma Corporation | Commercial Milestone Payments | Development and Commercialize Collaboration Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											175,000,000.0
Mitsubishi Tanabe Pharma Corporation | Upfront | Development and Commercialize Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Incurred clinical and commercial development cost											20,500,000
Mitsubishi Tanabe Pharma Corporation | Development Milestones One | Development And Commercialize Research And License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											6,000,000.0
Mitsubishi Tanabe Pharma Corporation | Development Milestones Two | Development And Commercialize Research And License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											4,000,000.0
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Development And Commercialize Research And License Agreement | Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable											0
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											$ 0
Number of performance obligations | Obligation											3
Deferred revenue											$ 45,944,000
Revenue on short-term or current liabilities											19,090,000
Collaborative arrangements cost sharing payments											279,900,000
Collaborative arrangements additional cost sharing payments amount											$ 60,000,000.0
Percentage of market penetration for license agreement											90.00%
License agreement, notice period for termination											12 months
Transaction price											$ 438,700,000
Reimbursement for Otsuka's share of costs previously incurred											$ 33,800,000
Transaction price, description											As of March 31, 2020, the transaction price totaling $438.7 million is comprised of: (i) the up-front payment of $125.0 million, (ii) the cost share payment with respect to amounts incurred by the Company through December 31, 2016 of $33.8 million, and (iii) the estimate of the net cost share consideration to be received of approximately $279.9 million with respect to amounts incurred by the Company subsequent to December 31, 2016 and the Additional Funding. As of March 31, 2020, no development or regulatory milestones have been assessed as probable of being reached and thus have been fully constrained.
Deferred revenue, noncurrent											$ 26,854,000
Cost share costs incurred											500,000		300,000
Reimbursable by Otsuka											300,000		200,000
Cost share costs by partner for license agreement											400,000		400,000
Reimbursable to Otsuka											200,000		200,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Global Development Plan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement for Otsuka's share of costs previously incurred								$ 33,800,000
Collaborative arrangements additional cost sharing payments expected amount											104,200,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | License, Collaboration and Other Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognized revenue under license agreement											38,577,000		26,223,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable											49,300,000				8,900,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Prepaid Expenses and Other Current Assets
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable											400,000				0
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Accrued Expenses and Other Current Liabilities
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue on short-term or current liabilities											$ 400,000				0
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of increase in funding to fund current global development costs											52.50%
Reduction in percentage of future payments due upon current global development costs creditable											50.00%
Percentage of remaining creditable amount applied to future payments											50.00%
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Minimum | Global Development Plan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative arrangements cost sharing payments											$ 279,900,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of increase in funding to fund current global development costs											80.00%
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of performance obligations | Obligation											3
Deferred revenue											$ 23,073,000
Revenue on short-term or current liabilities											$ 11,807,000
License agreement, notice period for termination											12 months
Transaction price											$ 286,200,000
Reimbursement for Otsuka's share of costs previously incurred											$ 200,000
Transaction price, description											As of March 31, 2020, the transaction price totaling $286.2 million is comprised of: (i) the up-front payment of $73.0 million, (ii) the cost share payment with respect to amounts incurred by the Company during the quarter ended March 31, 2017 of $0.2 million, and (iii) an estimate of the net cost share consideration to be received with respect to amounts incurred by the Company subsequent to March 31, 2017 of $213.0 million. As of March 31, 2020, no development or regulatory milestones have been assessed as probable of being reached and thus have been fully constrained.
Deferred revenue, noncurrent											$ 11,266,000
Estimate Subsequent Cost Share Payment Receivable											213,000,000.0
Milestone or royalty payments received					$ 0
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | Global Development Plan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement for Otsuka's share of costs previously incurred														$ 200,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | License, Collaboration and Other Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognized revenue under license agreement											19,370,000		21,956,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable											22,400,000				4,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | Prepaid Expenses and Other Current Assets
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable											200,000				0
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | Accrued Expenses and Other Current Liabilities
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue on short-term or current liabilities											200,000				$ 0
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | Minimum | Global Development Plan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Estimate Subsequent Cost Share Payment Receivable					213,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Regulatory Milestone Payments | Development and Commercialize United States Collaboration and License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											65,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Regulatory Milestone Payments | Development and Commercialize International Collaboration and License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue					52,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Development Milestones | Development and Commercialize United States Collaboration and License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received											125,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Development Milestones | Development and Commercialize International Collaboration and License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received					80,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Commercial Milestone Payments | Development and Commercialize United States Collaboration and License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											575,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Commercial Milestone Payments | Development and Commercialize International Collaboration and License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue					525,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Up-front, Non-refundable and Non-creditable | Development and Commercialize United States Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received									$ 125,000,000.0		125,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Up-front, Non-refundable and Non-creditable | Development and Commercialize International Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received					$ 73,000,000.0						73,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Development and Regulatory Milestones | Development and Commercialize United States Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											0
Otsuka Pharmaceutical Company. Ltd. | Development and Regulatory Milestones | Development and Commercialize International Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											$ 0
Janssen Pharmaceutica NV | Development And Commercialize Research And License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration Agreement, expiration period						10 years
Collaboration Agreement, notice period for termination						180 days
Upfront payment made in cash						$ 1,000,000.0
Warrant to purchase common stock, shares | shares						509,611
Janssen Pharmaceutica NV | Development And Commercialize Research And License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue						$ 215,000,000.0
Upfront cash payment received						$ 16,500,000
Johnson & Johnson Innovation | Development And Commercialize Research And License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Warrant to purchase common stock, shares | shares						509,611
Fair value of warrant								$ 3,400,000						$ 3,400,000
Exercise price | $ / shares						$ 9.81
Vifor (International) Ltd. | Research and Development Expense
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payments after closing of PRV purchase				$ 10,000,000.0
Vifor (International) Ltd. | License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue			$ 25,000,000.0	25,000,000.0
License agreement, notice period for termination											12 months
Deferred revenue, noncurrent				$ 4,700,000
Common stock shares sold | shares				3,571,429
Sale of stock, price per share | $ / shares				$ 14.00
Proceeds from common stock sold				$ 50,000,000.0
Premium over the closing stock price of common stock | $ / shares				$ 12.69
Premium amount over the closing stock price of common stock				$ 4,700,000
Vifor (International) Ltd. | Priority Review Voucher Letter Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payments after closing of PRV purchase		$ 10,000.0
Japan Tobacco Incorporation and Torii Pharmaceutical Company Limited | License, Collaboration and Other Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognized revenue under license agreement											$ 1,126,000		1,228,000
Japan Tobacco Incorporation and Torii Pharmaceutical Company Limited | License Agreement | Panion & BF Biotech, Incorporation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Royalty payments											$ 2,500,000		2,100,000
Japan Tobacco Incorporation and Torii Pharmaceutical Company Limited | Sublicense Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of performance obligations | Obligation											2
Recognized revenue under license agreement											$ 1,100,000		$ 1,200,000
License agreement, notice period for termination											6 months
Potential payment for achievement of annual net sales milestones											$ 55,000,000.0
Prior written notice for termination on the breach of agreement period											60 days

[1] Excludes accounts receivable from other services related to clinical and regulatory activities performed by the Company on behalf of MTPC that are not included in the performance obligations identified under the MTPC Agreement as of March 31, 2019 and 2020 and December 31, 2018 and 2019. Also excludes accounts receivable related to amounts due to the Company from product sales which are included in the accompanying unaudited condensed consolidated balance sheet as of March 31, 2020 and December 31, 2019.