Equity (Reclassifications Out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	$ 161	$ 117			$ 237	$ (443)
Net derivative gains (losses)	1,254	(378)			2,093	(88)
Net investment income	4,623	4,486			14,224	12,704
Other expenses	3,443	3,469			10,058	10,319
Income (loss) from continuing operations before provision for income tax	2,791	1,079			6,832	3,836
Income tax (expense) benefit	(601)	(164)			(1,511)	(770)
Net income (loss)	2,190	915	$ 3,131	$ 2,151	5,321	3,066
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	(219)	(101)			(76)	(411)
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)	84	101			200	(36)
Net derivative gains (losses)	12	(80)			28	(71)
Net investment income	(12)	9			(15)	9
Income (loss) from continuing operations before provision for income tax	84	30			213	(98)
Income tax (expense) benefit	(18)	(7)			(48)	22
Net income (loss)	66	23			165	(76)
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	(337)	(4)			(221)	(309)
Income tax (expense) benefit	75	(96)			49	47
Net income (loss)	(262)	(100)			(172)	(262)
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)	1	0			(1)	0
Net derivative gains (losses)	0	(2)			0	18
Net investment income	5	5			16	15
Other expenses	1	0			2	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)	(344)	0			(236)	0
Net derivative gains (losses)	0	(6)			0	(342)
Net investment income	0	(1)			(3)	(2)
Other expenses	0	0			1	1
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)	(37)			(108)	(108)
Amortization of prior service (costs) credit	7	6			20	15
Income (loss) from continuing operations before provision for income tax	(29)	(31)			(88)	(93)
Income tax (expense) benefit	6	7			19	20
Net income (loss)	$ (23)	$ (24)			$ (69)	$ (73)