Collaboration and Licensing Agreements - Additional Information (Detail) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended							12 Months Ended
	May 17, 2018 USD ($) item $ / shares shares	Mar. 31, 2017 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2019 USD ($) item	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Purchase of common stock value										$ 136,498	$ 92,063	$ 86,224
Revenue from contract with customer			$ 4,511	$ 5,785	$ 5,208	$ 4,382	$ 5,533	$ 5,062	$ 2,874	19,886	13,469	911
Collaborative Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue from contract with customer												313
Clinical Compound Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue from contract with customer										$ 140	33	68
Vifor Fresenius Medical Care Renal Pharma Ltd. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-refundable, non-creditable upfront payment	$ 50,000
Common stock, shares issued | shares	1,174,827
Purchase of common stock value	$ 20,000
Purchase common stock per share amount | $ / shares	$ 17.024
Closing prices of company common stock description	over a pre-determined average closing price of the Company's common stock.
Premium from sale of stock	$ 5,444
Contract liabilities	$ 55,444
Number of combined performance obligations for revenue recognized | item	1
Number of performance obligations for revenue recognized | item										2
Number of days to terminate agreement										60 days
Termination notice effective period										12 months
Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] | Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Third-party cost for clinical development	$ 20,000
Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] | Maximum [Member] | Regulatory and Commercial Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments receivable	470,000
Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] | Maximum [Member] | Regulatory Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments receivable	30,000
Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] | Maximum [Member] | Tiered Commercial Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments receivable	$ 440,000
Maruishi Pharmaceutical Co., Ltd. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of performance obligations for revenue recognized | item										2
Cost of clinical compound related to R&D expense										$ 126	30	61
Maruishi Pharmaceutical Co., Ltd. [Member] | License [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue from contract with customer		$ 843										843
Maruishi Pharmaceutical Co., Ltd. [Member] | Collaborative Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue from contract with customer												313
Maruishi Pharmaceutical Co., Ltd. [Member] | Clinical Compound Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue from contract with customer										$ 140	$ 33	$ 68