Collaboration and License Agreements - Additional Information (Detail) - USD ($)		1 Months Ended				3 Months Ended	6 Months Ended	12 Months Ended
	May 09, 2016	Dec. 31, 2017	Feb. 28, 2017	Dec. 31, 2016	May 31, 2016	Dec. 31, 2017	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration and license revenue								$ 82,497,000	$ 11,435,000
Avacopan Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non refundable upfront payments received					$ 85,000,000
Non refundable upfront payment received in cash					60,000,000
Non refundable upfront payment received in equity investment					$ 25,000,000
Share price of common stock in equity investment					$ 7.50
Non refundable upfront payment received in equity investment, shares					3,333,333
Non refundable upfront payments allocated for issuance of common stock	$ 7,000,000
Issuance of common stock, per share value	$ 2.10
Creditable upfront fee for CCX140 Agreement							$ 12,500,000
Non refundable upfront payments allocated for development and regulatory activities.							$ 65,500,000
Estimated period of performance							4 years 2 months 12 days
Amount of upfront fee expired										$ 12,500,000
Upfront cash commitment			$ 20,000,000
Upfront cash commitment received			$ 10,000,000
Non refundable upfront payment not reflected in accounts receivable								10,000,000
Additional Upfront cash commitment								20,000,000
Collaboration and license revenue								72,500,000	$ 11,400,000
Revenue recognized upon achievement of regulatory milestone		$ 50,000,000
CCX140 Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Estimated period of performance				5 years		8 years
Collaboration and license revenue								10,000,000
Non refundable upfront commitment								50,000,000
CCX140 Agreement [Member] | Up-front Payment Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration and license revenue								9,000,000
Maximum [Member] | Avacopan Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Estimated period of performance						5 years 4 months 24 days
Potential milestone payments receivable								460,000,000
Maximum [Member] | CCX140 Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments receivable								$ 625,000,000