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Strategic Collaborations and Other Significant Agreements - Additional Information (Details)				1 Months Ended				3 Months Ended		6 Months Ended	12 Months Ended
	Apr. 25, 2017 USD ($)	Apr. 02, 2017 USD ($)	Jan. 02, 2017 USD ($)	May 31, 2017 USD ($) $ / shares shares	Mar. 31, 2017 USD ($)	Feb. 28, 2017 USD ($) $ / shares shares	Jan. 31, 2016 USD ($)	Jun. 30, 2017 USD ($) $ / shares shares	Mar. 31, 2017 USD ($)	Jun. 30, 2017 USD ($) AccountingUnit $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										$ 236,700,000
Deferred revenue, noncurrent								$ 95,531,000		$ 95,531,000	$ 115,321,000
Number of accounting units \| AccountingUnit										3
Cost share payment received											33,800,000
Estimated cost share payment receivable			$ 153,600,000
Allocated arrangement consideration										$ 312,400,000
Recognized revenue under license agreement								28,520,000		49,385,000
Deferred revenue, current								$ 142,346,000		$ 142,346,000	$ 81,968,000
Common stock shares sold \| shares								42,490,957		42,490,957	38,615,709
Common stock, par value \| $ / shares								$ 0.00001		$ 0.00001	$ 0.00001
Upfront
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											$ 125,000,000
Otsuka U.S. Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue, noncurrent								$ 7,500,000		$ 7,500,000
Deferred revenue, current								112,300,000		112,300,000
Mitsubishi Tanabe Pharma Corporation \| Development and Commercialize Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Additional milestone payments to be received as development costs										60,000,000
Additional milestone payments to be received as development costs under local scenario										$ 0
Collaboration Agreement, expiration period										10 years
Collaboration Agreement, notice period for termination										12 months
Deferred revenue, noncurrent								40,000,000		$ 40,000,000
Mitsubishi Tanabe Pharma Corporation \| Development and Commercialize Collaboration Agreement \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										350,000,000
Mitsubishi Tanabe Pharma Corporation \| Development and Commercialize Collaboration Agreement \| Upfront
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue							$ 40,000,000
Milestone revenue refundable								20,000,000		20,000,000
Mitsubishi Tanabe Pharma Corporation \| Development and Commercialize Collaboration Agreement \| Upfront \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										100,000,000
Mitsubishi Tanabe Pharma Corporation \| Development and Commercialize Collaboration Agreement \| Additional Milestone Payments \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										250,000,000
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 \| Approval Milestones \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										65,000,000
Mitsubishi Tanabe Pharma Corporation \| Development and Commercialize Collaboration Agreement \| Sales Milestones \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										175,000,000
Otsuka Pharmaceutical Company. Ltd. \| Development and Commercialize United States Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										$ 0
Percentage of market penetration for license agreement										90.00%
License agreement, notice period for termination										12 months
Recognized revenue under license agreement								16,600,000		$ 37,500,000
Deferred revenue								119,800,000		119,800,000
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 \| Minimum \| Global Development Plan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Estimated fund			$ 153,600,000
Otsuka Pharmaceutical Company. Ltd. \| Development and Commercialize United States Collaboration and License Agreement \| Development Milestones \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										125,000,000
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]
Milestone revenue											$ 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 European Union Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue, noncurrent								43,300,000		43,300,000
Recognized revenue under license agreement								11,900,000		11,900,000
Deferred revenue								73,400,000		73,400,000
Deferred revenue, current								$ 30,100,000		$ 30,100,000
Milestone or royalty payments received	$ 0
Otsuka Pharmaceutical Company. Ltd. \| Development and Commercialize European Union 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 European Union Collaboration and License Agreement \| Minimum \| Global Development Plan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Estimated fund		$ 163,600,000
Otsuka Pharmaceutical Company. Ltd. \| Development and Commercialize European Union Collaboration and License Agreement \| Development Milestones \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue	80,000,000
Otsuka Pharmaceutical Company. Ltd. \| Development and Commercialize European Union Collaboration and License Agreement \| Up-front, Non-refundable and Non-creditable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue	73,000,000
Otsuka Pharmaceutical Company. Ltd. \| Development and Commercialize European Union 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 European Union Collaboration and License Agreement \| Commercial Milestone Payments \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue	$ 525,000,000
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
Warrant to purchase common stock, shares \| shares						509,611
Fair value of warrant					3,400,000				3,400,000
Aggregate specified development milestone payments payable						$ 16,500,000
Specified commercial milestones as well as tiered, escalating royalties payable						$ 215,000,000
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. \| License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue				$ 20,000,000
Deferred revenue, noncurrent				$ 4,700,000
License agreement, notice period for termination				12 months
Common stock shares sold \| shares				3,571,429
Common stock, par value \| $ / shares				$ 0.00001
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