Earnings (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Weighted-average shares used in basic earnings per share calculations		505.6	503.5	505.1	502.7
Stock options, restricted stock units and stock appreciation rights		5.9	7.7	6.1	6.8
Weighted-average shares used in diluted earnings per share calculations		511.5	511.2	511.2	509.5
Income from continuing operations:
Income from continuing operations		$ 435	$ 138	$ 465	$ 464
Less: net income from continuing operations attributable to noncontrolling interests		18	10	35	45
Income from continuing operations available to Genworth Financial, Inc.'s common stockholders		$ 417	$ 128	$ 430	$ 419
Basic per share		$ 0.83	$ 0.25	$ 0.85	$ 0.83
Diluted per share		$ 0.82	$ 0.25	$ 0.84	$ 0.82
Income (loss) from discontinued operations:
Income (loss) from discontinued operations, net of taxes		$ 1	$ (80)	$ (519)	$ 42
Less: net income from discontinued operations attributable to noncontrolling interests		0	30	0	101
Income (loss) from discontinued operations available to Genworth Financial, Inc.'s common stockholders		$ 1	$ (110)	$ (519)	$ (59)
Basic per share		$ 0	$ (0.22)	$ (1.03)	$ (0.12)
Diluted per share		$ 0	$ (0.21)	$ (1.02)	$ (0.12)
Net income (loss):
Income from continuing operations		$ 435	$ 138	$ 465	$ 464
Income (loss) from discontinued operations, net of taxes		1	(80)	(519)	42
Net income (loss)		436	58	(54)	506
Less: net income attributable to noncontrolling interests		18	40	35	146
Net income (loss) available to Genworth Financial, Inc.'s common stockholders		$ 418	$ 18	$ (89)	$ 360
Basic per share	[1]	$ 0.83	$ 0.04	$ (0.18)	$ 0.72
Diluted per share	[1]	$ 0.82	$ 0.04	$ (0.17)	$ 0.71

[1] May not total due to whole number calculation.