Subsequent Event - Additional Information (Detail)			12 Months Ended
	Jan. 31, 2020 USD ($) Tranche	Dec. 28, 2017 USD ($) Tranche	Dec. 31, 2019
Subsequent Event [Line Items]
Line of credit facility, interest rate description			Advances under the Credit Facility bear an interest rate equal to the greater of either (i) 8.05% plus the prime rate as reported from time to time in The Wall Street Journal minus 4.75%, and (ii) 8.05%. At December 31, 2019, the interest rate on the outstanding borrowings under the Credit Facility was 8.05%. For advances made under the first and second tranches, the Company will make interest-only payments through July 1, 2021, and will then repay the principal balance and interest on the advances in equal monthly installments after the interest-only period and continuing through December 1, 2022.
Line of credit facility, interest rate		8.05%
Subsequent Event [Member]
Subsequent Event [Line Items]
Line of credit facility, interest rate description	The initial interest rate equals to the greater of either (i) 8.50% plus the prime rate as reported in The Wall Street Journal minus 5.25%, and (ii) 8.50%, which may be reduced upon the Company achieving certain cumulative net avacopan revenue levels.
Line of credit facility, interest rate	8.50%
Term Loan [Member]
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity		$ 50,000,000
Number of tranches | Tranche		3
Line of credit facility, interest rate			8.05%
Line of credit facility, prepayment description		The Company may prepay advances under the Credit Facility, in whole or in part, at any time, subject to a prepayment charge equal to: (a) 1.5% of the amount so prepaid, if such prepayment occurs during the second year following the Closing Date; and (b) 1.0% of the amount so prepaid, if such prepayment occurs after the second year following the Closing Date. The Credit Facility is secured by substantially all of the Company’s assets, excluding intellectual property.
Term Loan [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity	$ 100,000,000
Number of tranches | Tranche	3
Line of credit facility, prepayment description	The Company may prepay advances under the Restated Credit Facility, in whole or in part, at any time subject to a prepayment charge up to 2.0% of prepayment amounts. In addition, the Company will pay an end of term charge of 7.15% of the aggregate amount of the advances. The Restated Credit Facility is secured by substantially all of the Company’s assets, excluding intellectual property.
Line of credit facility, prepayment interest rate	2.00%
End of term charge advances, percentage	7.15%
Term Loan [Member] | Subsequent Event [Member] | Minimum [Member]
Subsequent Event [Line Items]
Aggregate Equity Financing Minimum	$ 30,000,000
Term Loan [Member] | Subsequent Event [Member] | Hercules Capital Inc [Member] | Maximum [Member]
Subsequent Event [Line Items]
Amount of participation in equity financing	3,000,000
Through December 15, 2020 [Member] | Subsequent Event [Member] | Tranche One [Member]
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity	40,000,000
Through December 15, 2020 [Member] | Subsequent Event [Member] | Tranche One [Member] | New Drug Application (NDA) [Member]
Subsequent Event [Line Items]
Line of credit facility, capacity available for specific purpose other than for trade purchases	20,000,000
On or Before March 15, 2020 [Member] | Subsequent Event [Member] | Tranche One [Member]
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity	5,000,000
Through December 15, 2021 [Member] | Subsequent Event [Member] | Tranche Two [Member] | New Drug Application (NDA) [Member]
Subsequent Event [Line Items]
Restated credit facility, maximum borrowing capacity	30,000,000
Through December 15, 2022 [Member] | Subsequent Event [Member] | Tranche Three [Member]
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity	$ 30,000,000