Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Condensed Consolidated Statements of Comprehensive Income
Non-credit component of impaired losses on fixed maturities available-for-sale	$ 2,919	$ 1,215	$ 6,645	$ 6,933

Represents the before tax and reclassification adjustments amount of the non-credit component of impairment losses on fixed maturities available-for-sale securities.

No definition available.

Name:	gac_OtherComprehensiveIncomeNonCreditComponentOfImpairmentLossesOnFixedMaturitiesSecuritiesArisingDuringPeriodBeforeTax
Namespace Prefix:	gac_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration