Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	$ 1,658	$ 935	$ 718	$ 1,837
Cumulative effect of change in accounting principle, net of income tax					$ (4)
Restated balance, beginning of period	2,674	935	2,674	815	1,837
OCI before reclassifications	1,358	(199)	2,546	(1,294)
Deferred income tax benefit (expense)	(283)	58	(533)	291
AOCI before reclassifications, net of income tax	2,733	794	2,731	755
Amounts reclassified from AOCI	(74)	30	(72)	80
Deferred income tax benefit (expense)	15	(9)	15	(20)
Amounts reclassified from AOCI, net of income tax	(59)	21	(57)	60
Balance, end of period	2,674	815	2,674	815
Unrealized Investment Gains (Losses), Net of Related Offsets (1)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	1,551	870	564	1,709
Cumulative effect of change in accounting principle, net of income tax					(79)
Restated balance, beginning of period	1,551	870	564	671	1,709
OCI before reclassifications	1,278	(311)	2,500	(1,335)
Deferred income tax benefit (expense)	(268)	82	(525)	300
AOCI before reclassifications, net of income tax	2,561	641	2,539	595
Amounts reclassified from AOCI	(51)	41	(23)	99
Deferred income tax benefit (expense)	11	(11)	5	(23)
Amounts reclassified from AOCI, net of income tax	(40)	30	(18)	76
Balance, end of period	2,521	671	2,521	671
Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	133	86	180	151
Cumulative effect of change in accounting principle, net of income tax					0
Restated balance, beginning of period	133	86	180	151	151
OCI before reclassifications	73	108	39	35
Deferred income tax benefit (expense)	(15)	(23)	(8)	(8)
AOCI before reclassifications, net of income tax	191	171	211	178
Amounts reclassified from AOCI	(23)	(11)	(49)	(19)
Deferred income tax benefit (expense)	4	2	10	3
Amounts reclassified from AOCI, net of income tax	(19)	(9)	(39)	(16)
Balance, end of period	172	162	172	162
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(26)	(21)	(26)	(23)
Cumulative effect of change in accounting principle, net of income tax					0
Restated balance, beginning of period	(26)	(21)	(19)	(18)	(23)
OCI before reclassifications	7	4	7	6
Deferred income tax benefit (expense)	0	(1)	0	(1)
AOCI before reclassifications, net of income tax	(19)	(18)	(19)	(18)
Amounts reclassified from AOCI	0	0	0	0
Deferred income tax benefit (expense)	0	0	0	0
Amounts reclassified from AOCI, net of income tax	0	0	0	0
Balance, end of period	$ (19)	$ (18)	$ (19)	(18)
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
Restated balance, beginning of period				1,758	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
Restated balance, beginning of period				1,630	1,630
Restatement Adjustment | Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period				151
Restated balance, beginning of period				151	151
Restatement Adjustment | Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period				(23)
Restated balance, beginning of period				$ (23)	$ (23)