License, Collaboration and Other Significant Agreements - Additional Information (Details)								1 Months Ended		3 Months Ended
		Apr. 08, 2019 USD ($)	Apr. 01, 2019 USD ($)	Oct. 24, 2018 USD ($)	May 12, 2017 USD ($) $ / shares shares	Apr. 25, 2017 USD ($)	Feb. 09, 2017 USD ($) $ / shares shares	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Mar. 31, 2019 USD ($) Obligation shares	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognized revenue under license agreement										$ 72,666,000	$ 45,930,000
Deferred revenue										106,471,000
Deferred revenue, current										49,584,000			$ 56,980,000
Deferred revenue, noncurrent										$ 56,887,000			$ 55,709,000
Common stock shares sold | shares										117,122,262			116,887,518
Panion & BF Biotech, Incorporation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
License agreement payment				$ 500,000
License, Collaboration and Other Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognized revenue under license agreement										$ 49,555,000	45,930,000
Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable	[1]									29,933,000	35,587,000		$ 1,587,000	$ 34,186,000
Accounts Payable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue													13,492,000
Mitsubishi Tanabe Pharma Corporation | License, Collaboration and Other Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognized revenue under license agreement										$ 0	9,092,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration Agreement, expiration period										10 years
Collaboration Agreement, notice period for termination										12 months
Upfront cash payment received										$ 20,000,000
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 | Development, Regulatory and Commercial Events | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										$ 225,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Development Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										10,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Development Milestones | Subsequent Event
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue			$ 10,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Development Milestones | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received										40,000,000
Milestone revenue										175,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Regulatory Milestone Payments | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received										40,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Commercial Milestone Payments | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										175,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Upfront
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Incurred clinical and commercial development cost										20,500,000
Mitsubishi Tanabe Pharma Corporation | New Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Data access fee receivable															$ 25,000,000
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
Cost of research services										20,500,000
Deferred revenue										0
Mitsubishi Tanabe Pharma Corporation | Development And Commercialize Research And License Agreement | Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable										0
Mitsubishi Tanabe Pharma Corporation | Development And Commercialize Research And License Agreement | Regulatory Milestone Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										0
Mitsubishi Tanabe Pharma Corporation | Development And Commercialize Research And License Agreement | Development Milestones One
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										6,000,000
Mitsubishi Tanabe Pharma Corporation | Development And Commercialize Research And License Agreement | Development Milestones Two
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										4,000,000
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										$ 62,418,000
Collaborative arrangements cost sharing payments										$ 168,600,000
Percentage of market penetration for license agreement										90.00%
License agreement, notice period for termination										12 months
Transaction price										$ 327,400,000
Reimbursement for Otsuka's share of costs previously incurred										$ 33,800,000
Transaction price, description										As of March 31, 2019, the transaction price totaling $327.4 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 cost share payments to be received of approximately $168.6 million with respect to amounts incurred by the Company subsequent to December 31, 2016. As of March 31, 2019, no development or regulatory milestones have been assessed as probable of being reached and thus have been fully constrained.
Deferred revenue, current										$ 29,115,000
Deferred revenue, noncurrent										33,303,000
Cost share costs incurred										300,000	400,000
Reimbursable by Otsuka										200,000	100,000
Cost share costs by partner for license agreement										400,000	0
Reimbursable to Otsuka										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
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										26,223,000	19,599,000
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										$ 18,100,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Accounts Payable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue, current													7,200,000
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										$ 168,600,000
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 United States Collaboration and License Agreement | Development Milestones | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received										$ 125,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Regulatory Milestone Payments | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										65,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Commercial Milestone Payments | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										575,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Up-front, Non-refundable and Non-creditable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received									$ 125,000,000	125,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Development and Regulatory Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										$ 0
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										$ 39,374,000
Transaction price										250,400,000
Reimbursement for Otsuka's share of costs previously incurred										$ 200,000
Transaction price, description										As of March 31, 2019, the transaction price totaling $250.4 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 cost share payments to be received with respect to amounts incurred by the Company subsequent to March 31, 2017 of $177.2 million. As of March 31, 2019, no development or regulatory milestones have been assessed as probable of being reached and thus have been fully constrained.
Deferred revenue, current										$ 20,469,000
Deferred revenue, noncurrent										18,905,000
Estimate Subsequent Cost Share Payment Receivable										177,200,000
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										21,956,000	$ 16,974,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable										10,600,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | Accounts Payable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue, current													$ 6,300,000
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						177,200,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | Development Milestones | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received						80,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | Regulatory Milestone Payments | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue						52,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | Commercial Milestone Payments | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue						525,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | Up-front, Non-refundable and Non-creditable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment received						$ 73,000,000				73,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize International Collaboration and License Agreement | Development and Regulatory Milestones
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
Milestone revenue							$ 215,000,000
Upfront cash payment received							16,500,000
Upfront payment made in cash							$ 1,000,000
Warrant to purchase common stock, shares | shares							509,611
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. | License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue					$ 20,000,000
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
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. | License Agreement | Subsequent Event
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue		$ 25,000,000
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										$ 1,228,000
Japan Tobacco Incorporation and Torii Pharmaceutical Company Limited | License Agreement | Panion & BF Biotech, Incorporation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Royalty payments										$ 2,100,000
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										$ 1,200,000
License agreement, notice period for termination										6 months
Potential payment for achievement of annual net sales milestones										$ 55,000,000
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 and