License, Collaboration and Other Significant Agreements - Additional Information (Details)							1 Months Ended				3 Months Ended					6 Months Ended
	Feb. 14, 2020 USD ($)	Apr. 17, 2019	Apr. 08, 2019 USD ($)	May 12, 2017 USD ($) $ / shares shares	Apr. 25, 2017 USD ($)	Feb. 09, 2017 USD ($) $ / shares shares	Aug. 10, 2020 USD ($)	Jul. 31, 2019 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2020 USD ($) shares	Mar. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2017 USD ($)	Jun. 30, 2020 USD ($) performanceObligation shares	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue under license agreement											$ 90,142,000			$ 100,803,000		$ 178,620,000	$ 173,469,000
Deferred revenue											58,071,000					58,071,000
Revenue recognized											16,964,000			23,277,000		22,186,000	40,316,000
Deferred revenue, net of current portion											34,542,000					34,542,000		$ 33,120,000
Short-term deferred revenue											$ 23,529,000					$ 23,529,000		$ 39,830,000
Common stock, shares issued (in shares) | shares											143,129,409					143,129,409		121,674,568
License, collaboration and other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue under license agreement											$ 59,446,000			71,714,000		$ 118,715,000	121,269,000
Developmental Milestones | Otsuka Pharmaceutical Co. Ltd. | International
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone revenue (up to)											65,000,000.0					65,000,000.0
Accounts Receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable											18,808,000			8,157,000		18,808,000	8,157,000	$ 15,822,000	$ 1,587,000
Prepaid expenses and other current assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable											756,000					756,000		0
Accounts payable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue											5,651,000			0		5,651,000	0	0	$ 13,492,000
Mitsubishi Tanabe Pharma Corporation | License, collaboration and other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue under license agreement											15,000,000			$ 10,000,000		$ 15,000,000	10,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [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 | performanceObligation																2
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue											175,000,000.0					$ 175,000,000.0
Mitsubishi Tanabe Pharma Corporation | Development And Commercialize Research And License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue																10,000,000.0
Upfront cash payment received																20,000,000.0
Cost of research services																20,500,000
Deferred revenue											0					0
Accounts receivable											0					0
Mitsubishi Tanabe Pharma Corporation | Total Proportional Performance Revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront cash payment received											10,400,000
Revenue recognized											4,000,000.0					4,000,000.0
Deferred revenue, net of current portion											0					0
Mitsubishi Tanabe Pharma Corporation | Total Proportional Performance Revenue | Accounts Receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable											0					0
Mitsubishi Tanabe Pharma Corporation | Total Proportional Performance Revenue | Other Current Liabilities
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Short-term deferred revenue											6,400,000					6,400,000
Mitsubishi Tanabe Pharma Corporation | Regulatory Milestone Payments
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue								$ 10,000,000.0
Mitsubishi Tanabe Pharma Corporation | Regulatory Milestone Payments | Development and Commercialize Collaboration Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue													$ 10,000,000.0
Additional milestone revenue receivable											15,000,000.0					15,000,000.0
Mitsubishi Tanabe Pharma Corporation | Regulatory Milestone Payments | Development and Commercialize Collaboration Agreement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [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 Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue																10,000,000.0
Revenue recognized											10,000,000.0					10,000,000.0
Mitsubishi Tanabe Pharma Corporation | Development, Regulatory and Commercial Events | Development and Commercialize Collaboration Agreement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue																225,000,000.0
Mitsubishi Tanabe Pharma Corporation | Development Milestones | Development and Commercialize Collaboration Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue																10,000,000.0
Mitsubishi Tanabe Pharma Corporation | Commercial Milestone Payments | Development and Commercialize Collaboration Agreement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue											175,000,000.0					175,000,000.0
Mitsubishi Tanabe Pharma Corporation | Upfront | Development and Commercialize Collaboration Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [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 Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue																6,000,000.0
Mitsubishi Tanabe Pharma Corporation | Development Milestones Two | Development And Commercialize Research And License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue																4,000,000.0
Mitsubishi Tanabe Pharma Corporation | Regulatory Milestone, Approval Of Vadadustat In Japan | Development and Commercialize Collaboration Agreement | Subsequent Event
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Proceeds from collaborators							$ 15,000,000.0
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Development And Commercialize Research And License Agreement | Accounts Receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable											15,000,000.0					15,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Otsuka U.S. Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue																$ 0
Number of performance obligations | performanceObligation																3
Deferred revenue											35,935,000					$ 35,935,000
Deferred revenue, net of current portion											20,557,000					20,557,000
Short-term deferred revenue											$ 15,378,000					15,378,000
Collaborative arrangements cost sharing payments																290,600,000
Percentage of increase in funding to fund current global development costs										52.50%				80.00%
Collaborative arrangements additional cost sharing payments amount																$ 71,500,000
Percentage of market penetration for license agreement																90.00%
License agreement, notice period for termination																12 months
Transaction price																$ 449,400,000
Reimbursement for Otsuka's share of costs previously incurred																33,800,000
Transaction price, description											As of June 30, 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 June 30, 2020, no development or regulatory milestones have been assessed as probable of being reached and thus have been fully constrained.
Cost share costs incurred											$ 200,000			$ 300,000
Reimbursable by Otsuka											100,000			100,000
Cost share costs by partner for license agreement											400,000			100,000
Reimbursable to Otsuka											200,000			100,000
Otsuka Pharmaceutical Company. Ltd. | Otsuka U.S. Agreement | Global Development Plan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Reimbursement for Otsuka's share of costs previously incurred									$ 33,800,000
Collaborative arrangements additional cost sharing payments expected amount																106,400,000
Otsuka Pharmaceutical Company. Ltd. | Otsuka U.S. Agreement | License, collaboration and other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue under license agreement											25,888,000			37,519,000		64,465,000	63,742,000
Otsuka Pharmaceutical Company. Ltd. | Otsuka U.S. Agreement | Accounts Receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable																		8,900,000
Otsuka Pharmaceutical Company. Ltd. | Otsuka U.S. Agreement | Prepaid expenses and other current assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable											500,000					500,000
Otsuka Pharmaceutical Company. Ltd. | Otsuka U.S. Agreement | Accounts payable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue											3,900,000					$ 3,900,000
Otsuka Pharmaceutical Company. Ltd. | Otsuka U.S. Agreement | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
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. | Otsuka U.S. Agreement | Minimum | Global Development Plan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative arrangements cost sharing payments																$ 290,600,000
Otsuka Pharmaceutical Company. Ltd. | Otsuka International Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of performance obligations | performanceObligation																3
Deferred revenue											17,457,000					$ 17,457,000
Deferred revenue, net of current portion											9,306,000					9,306,000
Short-term deferred revenue											$ 8,151,000					8,151,000
License agreement, notice period for termination					12 months
Transaction price																287,500,000
Reimbursement for Otsuka's share of costs previously incurred																200,000
Transaction price, description											As of June 30, 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 June 30, 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 June 30, 2017 of $213.0 million. As of June 30, 2020, no development or regulatory milestones have been assessed as probable of being reached and thus have been fully constrained.
Estimated current global development costs subsequent to June 30, 2017															$ 214,300,000
Milestone or royalty payments received					$ 0
Otsuka Pharmaceutical Company. Ltd. | Otsuka International Agreement | Global Development Plan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Reimbursement for Otsuka's share of costs previously incurred															200,000
Otsuka Pharmaceutical Company. Ltd. | Otsuka International Agreement | License, collaboration and other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue under license agreement											$ 12,832,000			22,467,000		32,202,000	44,423,000
Otsuka Pharmaceutical Company. Ltd. | Otsuka International Agreement | Accounts Receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable																		$ 4,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Otsuka International Agreement | Prepaid expenses and other current assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable											200,000					200,000
Otsuka Pharmaceutical Company. Ltd. | Otsuka International Agreement | Accounts payable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue											1,800,000					1,800,000
Otsuka Pharmaceutical Company. Ltd. | Regulatory Milestone Payments | Otsuka U.S. Agreement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone revenue (up to)											65,000,000.0					65,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Regulatory Milestone Payments | Otsuka International Agreement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone revenue (up to)											52,000,000.0					52,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Development Milestones | Otsuka U.S. Agreement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront cash payment received																105,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Commercial Milestone Payments | Otsuka U.S. Agreement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue											575,000,000.0					575,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Commercial Milestone Payments | Otsuka International Agreement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue											525,000,000.0					525,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Up-front, Non-refundable and Non-creditable | Otsuka U.S. Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [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 | Otsuka International Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront cash payment received					$ 73,000,000.0											73,000,000.0
Otsuka Pharmaceutical Company. Ltd. | Development and Regulatory Milestones | Otsuka U.S. Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue																$ 0
Janssen Pharmaceutica NV | Development And Commercialize Research And License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration agreement, expiration period						10 years
Collaboration agreement, notice period for termination						180 days
Collaborative arrangement, term						3 years
Upfront payment made in cash						$ 1,000,000.0
Warrant to purchase common stock (in shares) | shares						509,611
Janssen Pharmaceutica NV | Development And Commercialize Research And License Agreement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [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 Arrangement and Arrangement Other than Collaborative [Line Items]
Warrant to purchase common stock (in shares) | shares						509,611
Fair value of warrant									$ 3,400,000						$ 3,400,000
Exercise price (in dollars per share) | $ / shares						$ 9.81
Vifor (International) Ltd. | Research and Development Expense
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payments after closing of PRV purchase												$ 10,000,000.0
Vifor (International) Ltd. | License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue			$ 25,000,000.0	$ 25,000,000.0
Deferred revenue, net of current portion				$ 4,700,000
License agreement, notice period for termination																12 months
Common stock, shares issued (in shares) | shares				3,571,429
Sale of stock, price per share (in dollars per share) | $ / shares				$ 14.00
Proceeds from common stock sold				$ 50,000,000.0
Premium over the closing stock price of common stock (in dollars per share) | $ / 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 Arrangement and Arrangement Other than Collaborative [Line Items]
Payments after closing of PRV purchase	$ 10,000,000.0
JT and Torii | License, collaboration and other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue under license agreement											1,740,000			1,491,000		$ 2,866,000	2,719,000
JT and Torii | License Agreement | Panion & BF Biotech, Incorporation
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License agreement, notice period for termination		90 days
Royalty payments											2,800,000			2,600,000		$ 5,300,000	4,700,000
JT and Torii | Sublicense Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of performance obligations | performanceObligation																2
Recognized revenue under license agreement											$ 1,700,000			$ 1,500,000		$ 2,900,000	$ 2,700,000
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