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Convertible Note Payable - Additional Information (Detail) - FibroGen China [Member] - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2013	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Convertible promissory note	$ 0.6
Interest rate of convertible promissory note	2.00%
Anniversary date of promissory note		8 years
Other Long Term Liabilities [Member]
Debt Instrument [Line Items]
Total outstanding principal balance and accrued interest		$ 0.7	$ 0.6

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- Definition

Anniversary date of promissory note.

+ References

No definition available.

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- Definition

Including the current and noncurrent portions, carrying amount of debt identified as being convertible into another form of financial instrument (typically the entity's common stock) as of the balance sheet date, which originally required full repayment more than twelve months after issuance or greater than the normal operating cycle of the company.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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- Definition

The average effective interest rate during the reporting period.

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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.

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