Condensed Consolidating Statement of Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 31, 2017	[2]	Sep. 30, 2017	[2]	Jun. 30, 2017	[2]	Mar. 31, 2017	[2]	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ (327)		$ 210		$ 249		$ 165		$ 265		$ 175		$ 271		$ 216		$ 297	$ 927	$ (67)
Other comprehensive income (loss), net of taxes:
Net unrealized gains (losses) on securities not other-than-temporarily impaired																	(669)	(187)	6
Net unrealized gains (losses) on other-than- temporarily impaired securities																	(2)	1	(9)
Derivatives qualifying as hedges																	(298)	(20)	40
Foreign currency translation and other adjustments																	(301)	251	54
Total other comprehensive income (loss)																	(1,270)	45	91
Total comprehensive income (loss)																	(973)	972	24
Less: comprehensive income attributable to noncontrolling interests																	22	222	217
Total comprehensive income (loss) available to Genworth Financial, Inc.'s common stockholders																	(995)	750	(193)
Reportable Legal Entities | Parent Guarantor
Condensed Financial Statements, Captions [Line Items]
Net income (loss)																	119	817	(277)
Other comprehensive income (loss), net of taxes:
Net unrealized gains (losses) on securities not other-than-temporarily impaired																	(652)	(178)	17
Net unrealized gains (losses) on other-than- temporarily impaired securities																	(2)	1	(9)
Derivatives qualifying as hedges																	(298)	(20)	40
Foreign currency translation and other adjustments																	(162)	130	36
Total other comprehensive income (loss)																	(1,114)	(67)	84
Total comprehensive income (loss)																	(995)	750	(193)
Total comprehensive income (loss) available to Genworth Financial, Inc.'s common stockholders																	(995)	750	(193)
Reportable Legal Entities | Issuer
Condensed Financial Statements, Captions [Line Items]
Net income (loss)																	(380)	589	(459)
Other comprehensive income (loss), net of taxes:
Net unrealized gains (losses) on securities not other-than-temporarily impaired																	(602)	(189)	14
Net unrealized gains (losses) on other-than- temporarily impaired securities																	(2)	1	(6)
Derivatives qualifying as hedges																	(299)	(19)	39
Foreign currency translation and other adjustments																	(129)	109	(28)
Total other comprehensive income (loss)																	(1,032)	(98)	19
Total comprehensive income (loss)																	(1,412)	491	(440)
Total comprehensive income (loss) available to Genworth Financial, Inc.'s common stockholders																	(1,412)	491	(440)
Reportable Legal Entities | All Other Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income (loss)																	533	1,170	450
Other comprehensive income (loss), net of taxes:
Net unrealized gains (losses) on securities not other-than-temporarily impaired																	(669)	(187)	7
Net unrealized gains (losses) on other-than- temporarily impaired securities																	(2)	1	(9)
Derivatives qualifying as hedges																	(310)	(19)	43
Foreign currency translation and other adjustments																	(301)	252	54
Total other comprehensive income (loss)																	(1,282)	47	95
Total comprehensive income (loss)																	(749)	1,217	545
Less: comprehensive income attributable to noncontrolling interests																	22	222	217
Total comprehensive income (loss) available to Genworth Financial, Inc.'s common stockholders																	(771)	995	328
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income (loss)																	25	(1,649)	219
Other comprehensive income (loss), net of taxes:
Net unrealized gains (losses) on securities not other-than-temporarily impaired																	1,254	367	(32)
Net unrealized gains (losses) on other-than- temporarily impaired securities																	4	(2)	15
Derivatives qualifying as hedges																	609	38	(82)
Foreign currency translation and other adjustments																	291	(240)	(8)
Total other comprehensive income (loss)																	2,158	163	(107)
Total comprehensive income (loss)																	2,183	(1,486)	112
Total comprehensive income (loss) available to Genworth Financial, Inc.'s common stockholders																	$ 2,183	$ (1,486)	$ 112

[1] In the fourth quarter of 2018, our long-term care insurance business recorded a $230 million unfavorable adjustment, net of taxes, related to its annual review of claim reserves, as described above. In addition, our long-term care insurance business recorded a $28 million unfavorable reserve adjustment, net of taxes, related to a refined estimate of unreported policy terminations. Our life insurance business recorded an unfavorable adjustment, net of taxes, of $91 million resulting from its annual review of assumptions, as described above. Our Canada mortgage insurance business recorded net investment losses, net of taxes, of $107 million, as described above.

[2] In the fourth quarter of 2017, we recorded $456 million of net tax benefits primarily from changes in U.S. tax legislation under the TCJA and other items. These tax benefits were mostly related to a $258 million release of a valuation allowance recorded in 2016, the impact from changes in the federal tax rate and the release of shareholder liability taxes, partially offset by higher transition taxes. Our valuation allowance was reduced by $258 million principally related to the TCJA and from improvements in business performance, mostly in our U.S. mortgage insurance business, as well as lower operating earnings volatility in our U.S. life insurance businesses. Our Australian mortgage insurance business completed a review of the premium earnings pattern, as described above, which resulted in an unfavorable adjustment of $152 million, net of taxes and noncontrolling interests. A portion of this loss, $11 million, was recorded in Corporate and Other activities in connection with our allocation methodology for income taxes. We also completed our annual review of assumptions in our life insurance business in the fourth quarter of 2017, as described above, which resulted in a $74 million unfavorable adjustment, net of taxes, in our universal and term universal life insurance products.