Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	$ 718	$ 1,837
Cumulative effect of change in accounting principle, net of income tax			$ (4)
OCI before reclassifications	1,188	(1,095)
Deferred income tax benefit (expense)	(250)	233
AOCI before reclassifications, net of income tax	1,656	896
Amounts reclassified from AOCI	2	50
Deferred income tax benefit (expense)	0	(11)
Amounts reclassified from AOCI, net of income tax	2	39
Balance, end of period	1,658	935
Unrealized Investment Gains (Losses), Net of Related Offsets (1)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	564	1,709
Cumulative effect of change in accounting principle, net of income tax			(79)
OCI before reclassifications	1,222	(1,024)
Deferred income tax benefit (expense)	(257)	218
AOCI before reclassifications, net of income tax	1,529	824
Amounts reclassified from AOCI	28	58
Deferred income tax benefit (expense)	(6)	(12)
Amounts reclassified from AOCI, net of income tax	22	46
Balance, end of period	1,551	870
Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	180	151
Cumulative effect of change in accounting principle, net of income tax			0
OCI before reclassifications	(34)	(73)
Deferred income tax benefit (expense)	7	15
AOCI before reclassifications, net of income tax	153	93
Amounts reclassified from AOCI	(26)	(8)
Deferred income tax benefit (expense)	6	1
Amounts reclassified from AOCI, net of income tax	(20)	(7)
Balance, end of period	133	86
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(26)	(23)
Cumulative effect of change in accounting principle, net of income tax			0
OCI before reclassifications	0	2
Deferred income tax benefit (expense)	0	0
AOCI before reclassifications, net of income tax	(26)	(21)
Amounts reclassified from AOCI	0	0
Deferred income tax benefit (expense)	0	0
Amounts reclassified from AOCI, net of income tax	0	0
Balance, end of period	$ (26)	(21)
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect of change in accounting principle, net of income tax			$ (79)
Restatement Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period		1,758
Restatement Adjustment | Unrealized Investment Gains (Losses), Net of Related Offsets (1)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period		1,630
Restatement Adjustment | Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period		151
Restatement Adjustment | Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period		$ (23)