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)	$ (10)	$ (4)
Net derivative gains (losses)	(1,310)	(287)
Net investment income	788	792
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(975)	(24)
Income tax (expense) benefit	221	22
Net income (loss)	(754)	(2)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	(2)	(39)
Reclassification out of Accumulated Other Comprehensive Income | Net unrealized investment gains (losses):
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	(24)	(58)
Net derivative gains (losses)	(4)	0
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(28)	(58)
Income tax (expense) benefit	6	12
Net income (loss)	(22)	(46)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on derivatives - cash flow hedges:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	26	8
Income tax (expense) benefit	(6)	(1)
Net income (loss)	20	7
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on derivatives - cash flow hedges: | Interest rate swaps
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net derivative gains (losses)	22	6
Net investment income	1	0
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on derivatives - cash flow hedges: | Interest rate forwards
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net derivative gains (losses)	0	1
Net investment income	0	1
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on derivatives - cash flow hedges: | Foreign currency swaps
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net derivative gains (losses)	$ 3	$ 0