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)	$ 61		$ (227)		$ 76	$ (560)
Net derivative gains (losses)	724		(59)		839	290
Net investment income	4,693		4,473		9,601	8,218
Other expenses	3,390		3,485		6,615	6,850
Income (loss) from continuing operations before provision for income tax	2,297		1,101		4,041	2,757
Income tax (expense) benefit	(551)		(207)		(910)	(606)
Net income (loss)	1,746	$ 1,385	894	$ 1,257	3,131	2,151
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	152		(389)		143	(310)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Investment Gains (Losses), Net of Related Offsets
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	140		(36)		116	(137)
Net derivative gains (losses)	(6)		(44)		16	9
Net investment income	(7)		(3)		(3)	0
Income (loss) from continuing operations before provision for income tax	127		(83)		129	(128)
Income tax (expense) benefit	(30)		19		(30)	29
Net income (loss)	97		(64)		99	(99)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains (Losses) on Derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from continuing operations before provision for income tax	92		(470)		116	(305)
Income tax (expense) benefit	(14)		170		(26)	143
Net income (loss)	78		(300)		90	(162)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains (Losses) on Derivatives | Interest Rate Contract
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	4		0		(2)	0
Net derivative gains (losses)	0		(1)		0	20
Net investment income	6		6		11	10
Other expenses	0		1		1	1
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains (Losses) on Derivatives | Foreign currency swaps
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	83		0		108	0
Net derivative gains (losses)	0		(475)		0	(336)
Net investment income	(1)		(1)		(3)	(1)
Other expenses	1		0		1	1
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains (Losses) on Derivatives | Credit derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	(1)		0		0	0
Reclassification out of Accumulated Other Comprehensive Income | Defined Benefit Plans Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of net actuarial gains (losses)	(36)		(35)		(72)	(71)
Amortization of prior service (costs) credit	6		4		13	9
Income (loss) from continuing operations before provision for income tax	(30)		(31)		(59)	(62)
Income tax (expense) benefit	7		6		13	13
Net income (loss)	$ (23)		$ (25)		$ (46)	$ (49)