Summary of Operating Results Related to Genworth Canada reported as Discontinued Operations (Parenthetical) (Detail) $ in Millions	3 Months Ended
Mar. 31, 2019 USD ($)
Parent Company [Member]
Discontinued operation pretax income attributable to parent	$ 56
Genworth Canada MI [Member]
Interest expense-term loan	$ 8

Amount of interest expense attributable to disposal group, including, but not limited to, discontinued operation.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration