Equity (Reclassifications Out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	$ 8	$ 15
Net derivative gains (losses)	(926)	1,335
Net investment income	5,196	4,559
Other expenses	(3,564)	(4,192)
Income (loss) from continuing operations before provision for income tax	817	2,922
Provision for income tax expense (benefit)	12	(719)
Net income (loss)	829	2,203
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	(11)	192
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)	(8)	(33)
Net derivative gains (losses)	(195)	13
Net investment income	7	3
Income (loss) from continuing operations before provision for income tax	(196)	(17)
Provision for income tax expense (benefit)	75	7
Net income (loss)	(121)	(10)
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	229	323
Provision for income tax expense (benefit)	(80)	(93)
Net income (loss)	149	230
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)	8	10
Net investment income	5	3
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)	(4)	2
Net investment income	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)	218	306
Other expenses	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)	(49)	(51)
Amortization of prior service (costs) credit	5	3
Income (loss) from continuing operations before provision for income tax	(44)	(48)
Provision for income tax expense (benefit)	5	20
Net income (loss)	$ (39)	$ (28)