Investments and Derivative Instruments Level 4 Available-for-Sale Securities (Details) - Fair Value Hierarchy [Domain] $ in Millions		Jun. 30, 2015 USD ($) Security	Dec. 31, 2014 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax		$ 203	$ 189
Available-for-sale Equity Securities, Amortized Cost Basis		167	525
Available-for-sale Securities, Equity Securities		178	514
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		213	208
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		1,697	2,374
Available-for-sale Securities, Amortized Cost
One year or less, amortized cost		768	1,031
Over one year through five years, amortized cost		5,315	4,902
Over five years through ten years, amortized cost		3,595	3,345
Over ten years, amortized cost		8,109	8,116
Available-for-sale Securities, Fair Value
One year or less, fair value		777	1,043
Over one year through five years, fair value		5,527	5,168
Over five years through ten years, fair value		3,695	3,501
Over ten years, fair value		9,082	9,661
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis		23,960	23,260
Available-for-sale Securities, Debt Securities		25,432	25,436
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis		6,173	5,866
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value		6,351	6,063
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Amortized Cost Basis		24,127	23,535
Available-for-sale Securities			25,702
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Amortized Cost		5,828	2,714
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		5,696	2,648
Available-for-sale Securities Continuous Unrealized Loss Position Twelve Months or Longer Amortized Cost		1,603	2,386
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		1,521	2,245
Available-for-sale Securities Continuous Unrealized Loss Position Amortized Cost		7,431	5,100
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		7,217	4,893
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		$ 1,676	2,364
Number of Securities Included in AFS Securities in Unrealized Loss Position | Security		2,277
Percentage of Gross Unrealized Losses Depressed Less than Twenty Percent of Cost or Amortized Cost		94.00%
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax		$ 21	10
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax		10	19
Fixed maturities available-for-sale, excluding mortgage-backed and asset-backed securities [Member]
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis		17,787	17,394
Available-for-sale Securities, Debt Securities		19,081	19,373
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax		28	30
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis		1,221	1,181
Available-for-sale Securities, Debt Securities		1,212	1,171
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Amortized Cost		293	368
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		292	367
Available-for-sale Securities Continuous Unrealized Loss Position Twelve Months or Longer Amortized Cost		295	340
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		268	311
Available-for-sale Securities Continuous Unrealized Loss Position Amortized Cost		588	708
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		560	678
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		19	20
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		0	0
Collateralized Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax		8	20
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis		1,340	1,083
Available-for-sale Securities, Debt Securities		1,421	1,148
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Amortized Cost	[1]	422	123
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	[1]	420	122
Available-for-sale Securities Continuous Unrealized Loss Position Twelve Months or Longer Amortized Cost	[1]	605	771
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	[1]	598	753
Available-for-sale Securities Continuous Unrealized Loss Position Amortized Cost	[1]	1,027	894
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	[1]	1,018	875
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		90	84
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		0	0
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax		15	7
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis		1,965	1,797
Available-for-sale Securities, Debt Securities		2,029	1,887
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Amortized Cost		473	109
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		463	108
Available-for-sale Securities Continuous Unrealized Loss Position Twelve Months or Longer Amortized Cost		100	194
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		95	188
Available-for-sale Securities Continuous Unrealized Loss Position Amortized Cost		573	303
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		558	296
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		79	97
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		3	3
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax		124	109
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis		14,583	14,166
Available-for-sale Securities, Debt Securities		15,644	15,742
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Amortized Cost		3,711	1,542
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		3,615	1,491
Available-for-sale Securities Continuous Unrealized Loss Position Twelve Months or Longer Amortized Cost		319	661
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		291	603
Available-for-sale Securities Continuous Unrealized Loss Position Amortized Cost		4,030	2,203
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		3,906	2,094
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		1,185	1,685
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		6	3
Foreign Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax		5	9
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis		337	576
Available-for-sale Securities, Debt Securities		351	602
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Amortized Cost		110	145
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		106	140
Available-for-sale Securities Continuous Unrealized Loss Position Twelve Months or Longer Amortized Cost		17	68
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		16	64
Available-for-sale Securities Continuous Unrealized Loss Position Amortized Cost		127	213
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		122	204
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		19	35
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		0	0
Municipal Bonds [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Amortized Cost		207	14
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		198	14
Available-for-sale Securities Continuous Unrealized Loss Position Twelve Months or Longer Amortized Cost		4	13
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		3	12
Available-for-sale Securities Continuous Unrealized Loss Position Amortized Cost		211	27
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		201	26
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax		10	1
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis		988	935
Available-for-sale Securities, Debt Securities		1,052	1,052
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		74	118
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		0	0
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax		10	12
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis		1,647	1,805
Available-for-sale Securities, Debt Securities		1,689	1,857
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Amortized Cost		288	148
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		286	147
Available-for-sale Securities Continuous Unrealized Loss Position Twelve Months or Longer Amortized Cost		201	229
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		193	218
Available-for-sale Securities Continuous Unrealized Loss Position Amortized Cost		489	377
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		479	365
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		52	64
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		0	0
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax		3	1
Available-for-sale Securities, Fair Value
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis		1,879	1,717
Available-for-sale Securities, Debt Securities		2,034	1,977
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Amortized Cost		267	184
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		264	184
Available-for-sale Securities Continuous Unrealized Loss Position Twelve Months or Longer Amortized Cost		11	18
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		11	17
Available-for-sale Securities Continuous Unrealized Loss Position Amortized Cost		278	202
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		275	201
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		158	261
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		0	0
Debt Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Amortized Cost		5,771	2,633
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		5,644	2,573
Available-for-sale Securities Continuous Unrealized Loss Position Twelve Months or Longer Amortized Cost		1,552	2,294
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		1,475	2,166
Available-for-sale Securities Continuous Unrealized Loss Position Amortized Cost		7,323	4,927
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		7,119	4,739
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		9	6
Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Equity Securities, Amortized Cost Basis		167
Available-for-sale Securities, Equity Securities		178	266
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities		25,610
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		9	6
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Equity Securities, Amortized Cost Basis			275
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Amortized Cost		57	81
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		52	75
Available-for-sale Securities Continuous Unrealized Loss Position Twelve Months or Longer Amortized Cost		51	92
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		46	79
Available-for-sale Securities Continuous Unrealized Loss Position Amortized Cost		108	173
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		98	154
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		0	0
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Equity Securities, Amortized Cost Basis		0	250
Available-for-sale Securities, Equity Securities		$ 0	$ 248

[1] Unrealized losses exclude the change in fair value of bifurcated embedded derivative features of certain securities, for which changes in fair value are recorded in net realized capital gains (losses).