XML 32 R20.htm IDEA: XBRL DOCUMENT v3.5.0.2

Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2016 Segment	Sep. 30, 2015 USD ($)
Accounting Policy [Line Items]
Number of operating segment | Segment		1
Out-of-Period Adjustment [Member]
Accounting Policy [Line Items]
Immaterial error correction		The out-of-period adjustment is immaterial to the previously filed financial statements and the current period financial statements as presented. The out-of-period adjustment had no impact to the financial statements
Out-of-Period Adjustment [Member] | Operating Expenses [Member]
Accounting Policy [Line Items]
Prior period reclassification adjustment	$ (2.2)
Reclassified from Cash and Cash Equivalents to Short-term Investments [Member]
Accounting Policy [Line Items]
Prior period reclassification adjustment			$ 8.5
Correction of Overstatement in Investing Activities [Member]
Accounting Policy [Line Items]
Prior period reclassification adjustment			$ (8.5)

X

- Definition

Accounting policy.

+ References

No definition available.

+ Details

Name:	fgen_AccountingPolicyLineItems
Namespace Prefix:	fgen_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Describes nature and related effect on financial statements related to corrections of prior year errors in the current year financial statements when the effect of the prior year error was immaterial to the prior year financial statements and the current year correction is immaterial to the current year financial statements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=64853466&loc=d3e22644-107794

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 1.N.Q2)
-URI http://asc.fasb.org/extlink&oid=26874127&loc=d3e30840-122693

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 1.M.1)
-URI http://asc.fasb.org/extlink&oid=26874127&loc=d3e30365-122693

+ Details

Name:	us-gaap_ImmaterialErrorCorrection
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The amount of a reclassification adjustment made to prior period financial statement amounts.

+ References

No definition available.

+ Details

Name:	us-gaap_PriorPeriodReclassificationAdjustment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

Name:	us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis=fgen_OutOfPeriodAdjustmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_OperatingExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis=fgen_ReclassificationFromCashAndCashEquivalentsToShortTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis=fgen_AdjustmentsToInvestingActivitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: