Equity (Reclassifications Out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	$ 56		$ (74)		$ 46	$ (78)
Net derivative gains (losses)	108		(278)		(1,202)	(565)
Net investment income	918		780		1,706	1,572
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	439		(229)		(536)	(253)
Income tax (expense) benefit	(76)		65		145	87
Net income (loss)	363	$ (754)	(164)	$ (2)	(391)	(166)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	59		(21)		57	(60)
Reclassification out of Accumulated Other Comprehensive Income | Net unrealized investment gains (losses):
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	74		(42)		50	(100)
Net derivative gains (losses)	(23)		0		(27)	0
Net investment income	0		1		0	1
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	51		(41)		23	(99)
Income tax (expense) benefit	(11)		11		(5)	23
Net income (loss)	40		(30)		18	(76)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on derivatives - cash flow hedges:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	23		11		49	19
Income tax (expense) benefit	(4)		(2)		(10)	(3)
Net income (loss)	19		9		39	16
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on derivatives - cash flow hedges: | Interest rate swaps
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net derivative gains (losses)	6		10		28	16
Net investment income	0		2		1	2
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on derivatives - cash flow hedges: | Interest rate forwards
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net derivative gains (losses)	0		0		0	1
Net investment income	0		0		0	1
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on derivatives - cash flow hedges: | Foreign currency swaps
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net derivative gains (losses)	$ 17		$ (1)		$ 20	$ (1)