Equity (Reclassifications Out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	$ 15	$ (333)
Net derivative gains (losses)	115	349
Net investment income	4,908	3,745
Other expenses	3,225	3,365
Income (loss) from continuing operations before provision for income tax	1,744	1,656
Provision for income tax expense (benefit)	359	399
Net income (loss)	1,385	1,257
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	(9)	79
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)	(24)	(101)
Net derivative gains (losses)	22	53
Net investment income	4	3
Income (loss) from continuing operations before provision for income tax	2	(45)
Provision for income tax expense (benefit)	0	(10)
Net income (loss)	2	(35)
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	24	165
Provision for income tax expense (benefit)	12	27
Net income (loss)	12	138
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)	(6)	0
Net derivative gains (losses)	0	21
Net investment income	5	4
Other expenses	1	0
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)	25	0
Net derivative gains (losses)	0	139
Net investment income	(2)	0
Other expenses	0	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
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)	(36)
Amortization of prior service (costs) credit	7	5
Income (loss) from continuing operations before provision for income tax	(29)	(31)
Provision for income tax expense (benefit)	(6)	(7)
Net income (loss)	$ (23)	$ (24)