Subsequent Event - Additional Information (Details) - NovaQuest Capital Management [Member] - Subsequent Event [Member] $ in Millions	Oct. 01, 2022 USD ($)
Subsequent Event [Line Items]
Cash upfront payment receivable	$ 50.0
Repayment description	FibroGen agreed to pay NovaQuest annually, up to certain caps (see below), 22.5% of all revenue recognized by the Company in respect of net sales of roxadustat in Europe and Japan and the other Astellas territories, and certain other tiered percentages of revenue (in each case paid annually), pursuant to FibroGen’s license and collaboration agreements with Astellas.
Aggregate royalties received 2028	$ 100.0
Aggregate royalties received 2029	112.5
Aggregate royalties received 2030	$ 125.0

FibroGen agreed to pay NovaQuest annually, up to certain caps (see below), 22.5% of all revenue recognized by the Company in respect of net sales of roxadustat in Europe and Japan and the other Astellas territories, and certain other tiered percentages of revenue (in each case paid annually), pursuant to FibroGen’s license and collaboration agreements with Astellas.

112.5