Summary of Significant Accounting Policies - Summary of Accounts Receivable (Parenthetical) (Detail) - CCX140 Agreement [Member] - USD ($) $ in Millions		12 Months Ended
Dec. 31, 2016	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash commitment due	$ 20.0
Vifor (International) Ltd [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash commitment due		$ 20.0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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