Accumulated Other Comprehensive Income (Loss) - Changes in AOCI, including Reclassification Adjustments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components Of Accumulated Other Comprehensive Income Loss [Line Items]
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	$ 9	$ (5)	$ (2)
Available-for-sale securities, Before-Tax Amount:
Other	(5)	5	0
Adjustments for amounts recognized in Net realized capital gains (losses) in the Consolidated Statements of Operations	69	29	70
DAC/VOBA and Sales inducements	360	(109)	(128)
Premium deficiency reserve adjustment	64	(25)	(23)
Change in unrealized gains/losses on available-for-sale securities	(905)	460	275
Available-for-sale securities, Income Tax:
Other	1	(2)	0
Adjustments for amounts recognized in Net realized capital gains (losses) in the Consolidated Statements of Operations	(14)	(10)	(25)
DAC/VOBA and Sales inducements	(76)	42	45
Premium deficiency reserve adjustment	(13)	9	8
Change in unrealized gains/losses on available-for-sale securities	195	(150)	(96)
Available-for-sale securities, After-Tax Amount:
Other	(4)	3	0
Adjustments for amounts recognized in Net realized capital gains (losses) in the Consolidated Statements of Operations	55	19	45
DAC/VOBA and Sales inducements	284	(67)	(83)
Premium deficiency reserve adjustment	51	(16)	(15)
Change in unrealized gains/losses on available-for-sale securities	(710)	310	179
Derivatives, Before-Tax Amount:
Derivatives	40	(53)	11
Adjustments related to effective cash flow hedges for amounts recognized in Net investment income in the Consolidated Statements of Operations	(24)	(24)	(19)
Change in unrealized gains/losses on derivatives	16	(77)	(8)
Derivatives, Income Tax:
Derivatives	(8)	19	(4)
Adjustments related to effective cash flow hedges for amounts recognized in Net investment income in the Consolidated Statements of Operations	5	8	7
Change in unrealized gains/losses on derivatives	(3)	27	3
Derivatives, After-Tax Amount:
Derivatives	32	(34)	7
Adjustments related to effective cash flow hedges for amounts recognized in Net investment income in the Consolidated Statements of Operations	(19)	(16)	(12)
Change in unrealized gains/losses on derivatives	13	(50)	(5)
OTTI:
Other-than-temporary impairments	8	(4)	9
Change in OTTI, Income Tax	(2)	1	(3)
Change in OTTI, After-Tax Amount	6	(3)	6
Pension and other post-employment benefit liability, Before-Tax Amount:
Amortization of prior service cost recognized in Operating expenses in the Consolidated Statements of Operations	(1)	(2)	(1)
Change in pension and other postretirement benefits liability	(1)	(2)	(1)
Other comprehensive income (loss), before tax	(890)	381	266
Pension and other post-employment benefit liability, Income Tax:
Amortization of prior service cost recognized in Operating expenses in the Consolidated Statements of Operations	0	1	0
Change in pension and other postretirement benefits liability	0	1	0
Other comprehensive income (loss)	192	(122)	(93)
Pension and other post-employment benefit liability, After-Tax Amount:
Amortization of prior service cost recognized in Operating expenses in the Consolidated Statements of Operations	(1)	(1)	(1)
Change in pension and other postretirement benefits liability	(1)	(1)	(1)
Other comprehensive income (loss), after tax	(698)	259	173
Fixed maturities
Available-for-sale securities, Before-Tax Amount:
Net unrealized gains/losses on securities	(1,401)	564	346
Available-for-sale securities, Income Tax:
Net unrealized gains/losses on securities	299	(190)	(121)
Available-for-sale securities, After-Tax Amount:
Net unrealized gains/losses on securities	(1,102)	374	225
Equity securities
Available-for-sale securities, Before-Tax Amount:
Net unrealized gains/losses on securities	0	0	1
Available-for-sale securities, Income Tax:
Net unrealized gains/losses on securities	0	0	0
Available-for-sale securities, After-Tax Amount:
Net unrealized gains/losses on securities	$ 0	$ 0	$ 1