XML 96 R67.htm IDEA: XBRL DOCUMENT
v3.20.4

Balance Sheet Components - Summary of Contractual Maturities of Available-for-Sale Investments (Detail) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Available For Sale Securities Debt Maturities [Abstract] |  |
Within one year - Bond and mutual funds | $ 8,144 |
Equity investments | 244 |
Total investments | $ 8,388 | $ 468,609

X
- Definition Available for sale securities bond and mutual funds maturing within one year. + References No definition available. + Details
Name: | fgen_AvailableForSaleSecuritiesBondAndMutualFundsMaturingWithinOneYear
Namespace Prefix: | fgen_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of equity securities categorized neither as held-to-maturity nor as trading. + References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesEquitySecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant