Accumulated Other Comprehensive Income Loss Level 4 (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 900	$ 188	$ 900	$ 188	$ 254	$ (329)	$ 1,150	$ 928
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	706	(935)	1,267	(677)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(60)	(27)	(38)	(63)
Other Comprehensive Income (Loss), Net of Tax	646	(962)	1,229	(740)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Gain (Loss) on Investments, Excluding Other than Temporary Impairments	60	20	(72)	37
Income Tax Expense (Benefit)	(46)	57	12	215
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	60		38
Other Postretirement Benefit Plan [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		27		63
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	2		7
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	(2)		2
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	15		30
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,437	1,657	2,437	1,657	1,801	1,279	2,578	2,370
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	696	(917)	1,191	(685)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(60)	(4)	(33)	(28)
Other Comprehensive Income (Loss), Net of Tax	636	(921)	1,158	(713)
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	60	4	33	28
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Gain (Loss) on Investments, Excluding Other than Temporary Impairments	92	6	51	43
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	92	6	51	43
Income Tax Expense (Benefit)	32	2	18	15
Accumulated Other-than-Temporary Impairment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(10)	(7)	(10)	(7)	(15)	(7)	(8)	(5)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	3	1	(6)	(3)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	2	0	3	1
Other Comprehensive Income (Loss), Net of Tax	5	1	(3)	(2)
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)	0	(3)	(1)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Gain (Loss) on Investments, Excluding Other than Temporary Impairments	(3)	0	(4)	(1)
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	(3)	0	(4)	(1)
Income Tax Expense (Benefit)	(1)	0	(1)	0
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	200	122	200	122	184	130	177	150
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	26	(41)	95	(10)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(10)	(14)	(25)	(18)
Other Comprehensive Income (Loss), Net of Tax	16	(55)	70	(28)
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	10	14	25	18
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	15	21	39	28
Income Tax Expense (Benefit)	5	7	14	10
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(68)	(24)	(68)	(24)	(49)	(55)	(28)	(8)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(19)	4	(13)	(16)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax	(19)	4	(13)	(16)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(1,659)	(1,560)	(1,659)	(1,560)	$ (1,667)	$ (1,676)	$ (1,569)	$ (1,579)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	18	0	37
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	8	(9)	17	(18)
Other Comprehensive Income (Loss), Net of Tax	8	9	17	19
Accumulated Defined Benefit Plans Adjustment [Member] | Other Postretirement Benefit Plan [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	(8)	9	(17)	18
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	1	(1)	3	(3)
Defined Benefit Plan, Actuarial Gain (Loss)	(14)	15	(29)	31
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	(13)	14	(26)	28
Income Tax Expense (Benefit)	(5)	5	(9)	10
Designated as Hedging Instrument [Member] | Cash Flow Hedging [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	15	21	39	28
Designated as Hedging Instrument [Member] | Gain (Loss) on Investments [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [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	2		7	3
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		2
Designated as Hedging Instrument [Member] | Gain (Loss) on Investments [Member] | Currency Swap [Member] | Cash Flow Hedging [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	(2)		2	(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		3
Designated as Hedging Instrument [Member] | Investment Income [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [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	$ 15		$ 30
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
Designated as Hedging Instrument [Member] | Interest Income [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [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				$ 32