Accumulated Other Comprehensive Income Loss Level 4 (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 494		$ 494		$ (207)	$ (337)	$ 254	$ (329)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	282	$ 706	439	$ 1,267
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	419	(60)	392	(38)
Other Comprehensive Income (Loss), Net of Tax	701	646	831	1,229
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Gain (Loss) on Investments, Excluding Other than Temporary Impairments	89	60	70	(72)
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements			747	0
Income Tax Expense (Benefit)	(99)	(46)	10	12
Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(419)	60	(392)	38
Gain (Loss) on Investments [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0		4
Gain (Loss) on Investments [Member] | Currency Swap [Member] | Cash Flow Hedging [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	5		6
Investment Income [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	16		32
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	1,755	2,437	1,755	2,437	1,413	1,276	1,801	1,279
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	404	696	564	1,191
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(62)	(60)	(85)	(33)
Other Comprehensive Income (Loss), Net of Tax	342	636	479	1,158
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	62	60	85	33
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Gain (Loss) on Investments, Excluding Other than Temporary Impairments	95	92	131	51
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	95	92	131	51
Income Tax Expense (Benefit)	33	32	46	18
Accumulated Other-than-Temporary Impairment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(3)	(10)	(3)	(10)	(4)	(3)	(15)	(7)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	1	3	0	(6)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	2	0	3
Other Comprehensive Income (Loss), Net of Tax	1	5	0	(3)
Accumulated Other-than-Temporary Impairment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(2)		(3)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Gain (Loss) on Investments, Excluding Other than Temporary Impairments		(3)		(4)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		(3)		(4)
Income Tax Expense (Benefit)		(1)		(1)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	57	200	57	200	58	76	184	130
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	13	26	8	95
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(14)	(10)	(27)	(25)
Other Comprehensive Income (Loss), Net of Tax	(1)	16	(19)	70
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Cash Flow Hedging [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	14	10	27	25
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	21		42
Income Tax Expense (Benefit)	7	5	15	14
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	13	(68)	13	(68)	8	6	(49)	(55)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	5	(19)	7	(13)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax	5	(19)	7	(13)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(1,328)	(1,659)	(1,328)	(1,659)	$ (1,682)	(1,692)	$ (1,667)	(1,676)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(141)	0	(140)	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	495	8	504	17
Other Comprehensive Income (Loss), Net of Tax	354	8	364	17
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	144
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] | Other Pension Plan, Postretirement or Supplemental Plans [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(495)	(8)	(504)	(17)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	2	1	3	3
Defined Benefit Plan, Actuarial Gain (Loss)	(16)	(14)	(32)	(29)
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	747		747
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(761)	(13)	(776)	(26)
Income Tax Expense (Benefit)	(266)	(5)	(272)	(9)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	494	900	494	900		$ (337)		$ (329)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), Net of Tax			831	1,229
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	21	15	42
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		15		39
Designated as Hedging Instrument [Member] | Gain (Loss) on Investments [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	2	4	7
Designated as Hedging Instrument [Member] | Gain (Loss) on Investments [Member] | Currency Swap [Member] | Cash Flow Hedging [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	5	(2)	6	2
Designated as Hedging Instrument [Member] | Investment Income [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 16	$ 15	$ 32	$ 30