Accumulated Other Comprehensive Income Level 4 Reclassification of AOCI (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other net realized capital losses		$ (46)	$ (135)	$ (85)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		376	356	530
Income Tax Expense (Benefit)		422	74	30
Net Income (Loss) Attributable to Parent		(46)	282	500
Net Investment Income		1,281	1,373	1,456
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		122	74	(3)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other net realized capital losses	$ 0	153	89	(27)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		153	89	(27)
Income Tax Expense (Benefit)		54	31	(9)
Net Income (Loss) Attributable to Parent		99	58	(18)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		36	24	23
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Interest Rate Swap [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other net realized capital losses		(1)	1	(1)
Net Investment Income		26	25	33
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Gain (Loss) on Investments [Member] | Cash Flow Hedging [Member] | Currency Swap [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		11	(2)	(9)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI, Current Period, Tax		13	8	8
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		$ 23	$ 16	$ 15