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)	$ 14	$ (42)			$ 60	$ (120)
Net investment income	904	828			2,610	2,400
Net derivative gains (losses)	984	(665)			(218)	(1,230)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	708	(407)			172	(660)
Income tax (expense) benefit	(99)	108			46	195
Net income (loss)	609	(299)	$ (391)	$ (166)	218	(465)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	14	6			71	(54)
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)	17	(36)			67	(136)
Net investment income	0	0			0	1
Net derivative gains (losses)	0	(1)			(27)	(1)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	17	(37)			40	(136)
Income tax (expense) benefit	(3)	8			(8)	31
Net income (loss)	14	(29)			32	(105)
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	1	46			50	65
Income tax (expense) benefit	(1)	(11)			(11)	(14)
Net income (loss)	0	35			39	51
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 investment income	1	0			2	2
Net derivative gains (losses)	0	15			28	31
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 investment income	0	1			0	2
Net derivative gains (losses)	0	30			0	31
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)	$ 0	$ 0			$ 20	$ (1)