Fair Value Measurements Level 4 Fair Value Option (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 2,089	$ 2,378	$ 2,089	$ 2,378	$ 2,220	$ 2,249	$ 2,240	$ 2,140
Changes in fair value of assets and liabilities accounted for using the fair value option	2	2	2	(32)
Assets, Fair Value Disclosure	139,163		139,163		137,423
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	(22)	8	(74)	16
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	16	30	33	14
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	169	98	463	288
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	156	156	202	194
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	48	43	120	58
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	59	279	70	328
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	178	78	301	156
Fixed Maturities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Changes in fair value of assets and liabilities accounted for using the fair value option	(1)	2	0	2
Residential Mortgage Backed Securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Changes in fair value of assets and liabilities accounted for using the fair value option	(1)	2	0	2
Equity Securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Changes in fair value of assets and liabilities accounted for using the fair value option	3	0	2	(34)
Equity Securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Assets, Fair Value Disclosure	0		0		0
Fixed Maturities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Assets, Fair Value Disclosure	58		58		82
Fixed Maturities [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Assets, Fair Value Disclosure	58		58		82
Fair Value, Inputs, Level 3 [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	192	171	192	171	201	277	154	139
Assets, Fair Value Disclosure	2,049		2,049		2,182
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	2	0	3
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	0	3	2	(7)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	13	22	111	61
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	2	3	7	9
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	34	6	42	16
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	7	3	10	6
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	(71)	(2)	(86)	17
Fair Value, Inputs, Level 3 [Member] | Fixed Maturities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		0		0			1	2
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		1		1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		(2)
Fair Value, Inputs, Level 3 [Member] | Derivative [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(3)	7	(47)	8
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	171	273	171	273	218	176	260	253
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	(5)	7	(47)	8
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases		0		8
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements	0	0	0	2
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Sales	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3		0		0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3	0	(6)	0	(6)
US GMWB Hedging Instruments [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(5)	15	(41)	24
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	40	165	40	165	81	46	144	135
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	(6)	15	(41)	24
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Sales	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3	0	(6)	0	(6)
US Macro Hedge Program [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Change in Unrealized Gain (Loss)	2	(4)	(6)	(4)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	160	141	160	141	167	159	145	147
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	1	(4)	(7)	(4)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements	0	0	0	2
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Sales	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3	0	0	0	0
Equity Contract [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	(2)	0	(7)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs		1		1			3	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings		(2)		(7)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases		0		8
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements		0		0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Sales		0		0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3		0		0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3		0		0
Interest Rate Contract [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	(2)		(5)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(29)	34	(29)	34	$ (30)	$ (29)	$ (32)	$ (29)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	0	(2)	1	(5)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Sales	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3	$ 0	$ 0	$ 0	$ 0
Credit Default Swap, Selling Protection [Member] | External Credit Rating, Investment Grade [Member] | Debt Securities Payable [Member] | Standard & Poor's, A+ Rating [Member] | Embedded Derivative Financial Instruments [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Average Term of Credit Risk Derivatives					1 year
Less than 1 year [Member] | Credit Default Swap, Selling Protection [Member] | External Credit Rating, Non Investment Grade [Member] | Collateralized Mortgage Backed Securities [Member] | Standard & Poor's, CCC Rating [Member] | Basket Credit Default Swaps [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Average Term of Credit Risk Derivatives			1 year