Quarterly Results of Operations (Parenthetical) (Detail) (Government Guarantee Agreement, USD $) In Millions, unless otherwise specified	3 Months Ended
Dec. 31, 2012
Government Guarantee Agreement
Quarterly Financial Information [Line Items]
Favorable adjustment to exit fee accrual	$ 186
Impact of favorable adjustment to exit fee accrual on net income available to Genworth Financial, Inc.'s common stockholders	78
Impact of favorable adjustment to exit fee accrual on net income attributable to noncontrolling interests	$ 58

Impact of favorable after-tax adjustment recorded to expenses for the reversal of the accrued liability for exit fees associated with the Government Guarantee Agreement in Canada on net income attributable to noncontrolling interest.

No definition available.

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Namespace Prefix:	gnw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration