Equity (Reclassifications Out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	$ 104	$ 266	$ 112	$ 281
Net derivative gains (losses)	(437)	(2,099)	(1,363)	(764)
Net investment income	4,959	4,887	10,155	9,446
Other expenses	(4,059)	(3,246)	(7,623)	(7,438)
Income (loss) from continuing operations before provision for income tax	1,002	(100)	1,819	2,822
Provision for income tax expense (benefit)	(115)	214	(103)	(505)
Net income (loss)	887	114	1,716	2,317
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	281	(87)	270	105
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)	46	158	38	125
Net derivative gains (losses)	5	9	(190)	22
Net investment income	(4)	16	3	19
Income (loss) from continuing operations before provision for income tax	47	183	(149)	166
Provision for income tax expense (benefit)	(22)	(61)	53	(54)
Net income (loss)	25	122	(96)	112
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	429	(243)	658	80
Provision for income tax expense (benefit)	(149)	68	(229)	(25)
Net income (loss)	280	(175)	429	55
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains (Losses) on Derivatives | Interest rate swaps
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net derivative gains (losses)	6	18	14	28
Net investment income	4	4	9	7
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains (Losses) on Derivatives | Interest rate forwards
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net derivative gains (losses)	2	(1)	(2)	1
Net investment income	2	2	3	3
Other expenses	1	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 derivative gains (losses)	414	(269)	632	37
Net investment income	(1)	(1)	(1)	(1)
Other expenses	0	0	1	1
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains (Losses) on Derivatives | Credit forwards
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net derivative gains (losses)	1	3	1	3
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)	(48)	(52)	(97)	(103)
Amortization of prior service (costs) credit	7	1	12	4
Income (loss) from continuing operations before provision for income tax	(41)	(51)	(85)	(99)
Provision for income tax expense (benefit)	17	17	22	37
Net income (loss)	$ (24)	$ (34)	$ (63)	$ (62)