Investments - Number of Fixed Maturity Securities with Gross Unrealized Gains and Losses (Detail) - Security	Dec. 31, 2017	Dec. 31, 2016
Investments Debt And Equity Securities [Abstract]
Number of Securities with Gross Unrealized Losses Less than or equal to 12 months	12	37
Number of Securities with Gross Unrealized Losses Greater than 12 months	26	0
Number of Securities with Gross Unrealized Gains	31	40

Number of available for sale securities continuous unrealized loss position less than twelve months.

No definition available.

Name:	fac_NumberOfAvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonths
Namespace Prefix:	fac_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant