Fair Value Measurements Level 4 Significant Unobservable Inputs - Securities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	$ 13,839	$ 22,799
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	322	284
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	12,627	21,229
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	890	1,286
Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,033	1,427
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	590	735
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	443	692
US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	734	1,266
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	734	1,228
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	38
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	7,678	14,038
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	7,351	13,595
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	327	443
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,407	2,084
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,366	2,058
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	$ 41	$ 26
Credit Standing Adjustment [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Sensitivity Analysis, Description	Decrease
Credit Standing Adjustment [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Unobservable Input Range	0.28%
Credit Standing Adjustment [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Unobservable Input Range	0.04%
Living Benefits Required to be Fair Valued and the GMWB Reinsurance Derivative [Member] | Withdrawal Utilization [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Sensitivity Analysis, Description	Increase	Increase
Living Benefits Required to be Fair Valued and the GMWB Reinsurance Derivative [Member] | Withdrawal Utilization [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Unobservable Input Range	100.00%	100.00%
Living Benefits Required to be Fair Valued and the GMWB Reinsurance Derivative [Member] | Withdrawal Utilization [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Unobservable Input Range	15.00%	15.00%
Living Benefits Required to be Fair Valued and the GMWB Reinsurance Derivative [Member] | Withdrawal Rates [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Sensitivity Analysis, Description	Increase	Increase
Living Benefits Required to be Fair Valued and the GMWB Reinsurance Derivative [Member] | Withdrawal Rates [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Unobservable Input Range	8.00%	8.00%
Living Benefits Required to be Fair Valued and the GMWB Reinsurance Derivative [Member] | Withdrawal Rates [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Unobservable Input Range	0.00%	0.00%
Living Benefits Required to be Fair Valued and the GMWB Reinsurance Derivative [Member] | Lapse Rates [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Sensitivity Analysis, Description	Decrease	Decrease
Living Benefits Required to be Fair Valued and the GMWB Reinsurance Derivative [Member] | Lapse Rates [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Unobservable Input Range	40.00%	40.00%
Living Benefits Required to be Fair Valued and the GMWB Reinsurance Derivative [Member] | Lapse Rates [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Unobservable Input Range	1.00%	0.00%
Living Benefits Required to be Fair Valued and the GMWB Reinsurance Derivative [Member] | Reset Elections [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Sensitivity Analysis, Description	Increase	Increase
Living Benefits Required to be Fair Valued and the GMWB Reinsurance Derivative [Member] | Reset Elections [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Unobservable Input Range	45.00%	75.00%
Living Benefits Required to be Fair Valued and the GMWB Reinsurance Derivative [Member] | Reset Elections [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Unobservable Input Range	20.00%	30.00%
Other Contract [Member] | Equity Volatility [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Sensitivity Analysis, Description	Increase	Increase
Other Contract [Member] | Equity Volatility [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Unobservable Input Range	30.00%	30.00%
Other Contract [Member] | Equity Volatility [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Unobservable Input Range	17.00%	7.00%
Fair Value, Measurements, Recurring [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	$ 426	$ 692
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale		$ 22
Fair Value Measurements, Sensitivity Analysis, Description		Decrease
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	$ 144	$ 190
Fair Value Measurements, Sensitivity Analysis, Description	Decrease	Decrease
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	$ 1	$ 15
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Sensitivity Analysis, Description	Decrease	Decrease
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | Residential Mortgage Backed Securities [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	3.46	4.63
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | Residential Mortgage Backed Securities [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.31	0.24
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | Residential Mortgage Backed Securities [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.92	0.77
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | US States and Political Subdivisions Debt Securities [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input		2.50
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | US States and Political Subdivisions Debt Securities [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input		1.92
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | US States and Political Subdivisions Debt Securities [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input		2.28
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | Corporate Debt Securities [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	11.45	10.00
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | Corporate Debt Securities [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	1.45	1.03
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | Corporate Debt Securities [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	4.00	3.55
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Sensitivity Analysis, Description	Decrease	Decrease
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | Commercial Mortgage Backed Securities [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	18.16	18.16
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | Commercial Mortgage Backed Securities [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.09	0.09
Fair Value, Measurements, Recurring [Member] | Measurement Input, Credit Spread [Member] | Commercial Mortgage Backed Securities [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	2.78	4.57
Fair Value, Measurements, Recurring [Member] | Measurement Input, Constant Prepayment Rate [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Sensitivity Analysis, Description	Decrease [5]	Decrease [5]
Fair Value, Measurements, Recurring [Member] | Measurement Input, Constant Prepayment Rate [Member] | Residential Mortgage Backed Securities [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.13	0.25
Fair Value, Measurements, Recurring [Member] | Measurement Input, Constant Prepayment Rate [Member] | Residential Mortgage Backed Securities [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.00	0.00
Fair Value, Measurements, Recurring [Member] | Measurement Input, Constant Prepayment Rate [Member] | Residential Mortgage Backed Securities [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.06	0.06
Fair Value, Measurements, Recurring [Member] | Measurement Input, Default Rate [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Sensitivity Analysis, Description	Decrease	Decrease
Fair Value, Measurements, Recurring [Member] | Measurement Input, Default Rate [Member] | Residential Mortgage Backed Securities [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.08	0.07
Fair Value, Measurements, Recurring [Member] | Measurement Input, Default Rate [Member] | Residential Mortgage Backed Securities [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.02	0.00
Fair Value, Measurements, Recurring [Member] | Measurement Input, Default Rate [Member] | Residential Mortgage Backed Securities [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.03	0.04
Fair Value, Measurements, Recurring [Member] | Measurement Input, Loss Severity [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Sensitivity Analysis, Description	Decrease	Decrease
Fair Value, Measurements, Recurring [Member] | Measurement Input, Loss Severity [Member] | Residential Mortgage Backed Securities [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	1.00	1.00
Fair Value, Measurements, Recurring [Member] | Measurement Input, Loss Severity [Member] | Residential Mortgage Backed Securities [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.00	0.00
Fair Value, Measurements, Recurring [Member] | Measurement Input, Loss Severity [Member] | Residential Mortgage Backed Securities [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0.58	0.65