Fair Value of Financial Instruments (Fair Value Inputs Quantitative Information) (Details)	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 246,814,000,000	$ 245,265,000,000
Liabilities Fair Value Disclosure [Abstract]
Liabilities measured at fair value	(2,382,000,000)	(3,689,000,000)
Significant Unobservable Inputs (Level 3) [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	5,812,000,000	5,197,000,000
Liabilities Fair Value Disclosure [Abstract]
Liabilities measured at fair value	(1,945,000,000)	$ (2,058,000,000)
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Equity Securities [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 21,000,000
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Minimum [Member] | Equity Securities [Member] | Liquidity/Duration Adjustment [Member]
Liabilities Fair Value Disclosure [Abstract]
Equity securities, measurement input	0.045
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Maximum [Member] | Equity Securities [Member] | Liquidity/Duration Adjustment [Member]
Liabilities Fair Value Disclosure [Abstract]
Equity securities, measurement input	0.051
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Fixed Maturity AFS Securities [Member] | Corporate Bonds [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 2,445,000,000
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Fixed Maturity AFS Securities [Member] | ABS [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	23,000,000
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Fixed Maturity AFS Securities [Member] | Foreign Government Bonds [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	78,000,000
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Fixed Maturity AFS Securities [Member] | Hybrid And Redeemable Preferred Securities [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 4,000,000
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Fixed Maturity AFS Securities [Member] | Minimum [Member] | Corporate Bonds [Member] | Liquidity/Duration Adjustment [Member]
Liabilities Fair Value Disclosure [Abstract]
Fixed maturity AFS and trading securities, measurement input	0.005
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Fixed Maturity AFS Securities [Member] | Minimum [Member] | ABS [Member] | Liquidity/Duration Adjustment [Member]
Liabilities Fair Value Disclosure [Abstract]
Fixed maturity AFS and trading securities, measurement input	0.030
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Fixed Maturity AFS Securities [Member] | Minimum [Member] | Foreign Government Bonds [Member] | Liquidity/Duration Adjustment [Member]
Liabilities Fair Value Disclosure [Abstract]
Fixed maturity AFS and trading securities, measurement input	0.011
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Fixed Maturity AFS Securities [Member] | Minimum [Member] | Hybrid And Redeemable Preferred Securities [Member] | Liquidity/Duration Adjustment [Member]
Liabilities Fair Value Disclosure [Abstract]
Fixed maturity AFS and trading securities, measurement input	0.018
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Fixed Maturity AFS Securities [Member] | Maximum [Member] | Corporate Bonds [Member] | Liquidity/Duration Adjustment [Member]
Liabilities Fair Value Disclosure [Abstract]
Fixed maturity AFS and trading securities, measurement input	0.248
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Fixed Maturity AFS Securities [Member] | Maximum [Member] | ABS [Member] | Liquidity/Duration Adjustment [Member]
Liabilities Fair Value Disclosure [Abstract]
Fixed maturity AFS and trading securities, measurement input	0.030
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Fixed Maturity AFS Securities [Member] | Maximum [Member] | Foreign Government Bonds [Member] | Liquidity/Duration Adjustment [Member]
Liabilities Fair Value Disclosure [Abstract]
Fixed maturity AFS and trading securities, measurement input	0.028
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Fixed Maturity AFS Securities [Member] | Maximum [Member] | Hybrid And Redeemable Preferred Securities [Member] | Liquidity/Duration Adjustment [Member]
Liabilities Fair Value Disclosure [Abstract]
Fixed maturity AFS and trading securities, measurement input	0.018
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Other Assets [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 1,683,000,000
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Minimum [Member] | Other Assets [Member] | Long-Term Lapse Rate [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	0.01
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Minimum [Member] | Other Assets [Member] | Utilization Of Guaranteed Withdrawls [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	0.85
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Minimum [Member] | Other Assets [Member] | Claims Utilization Factor [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	0.60
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Minimum [Member] | Other Assets [Member] | Premiums Utilization Factor [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	0.80
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Minimum [Member] | Other Assets [Member] | NPR [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	0.0001
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Minimum [Member] | Other Assets [Member] | Volatility [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	0.01
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Maximum [Member] | Other Assets [Member] | Long-Term Lapse Rate [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	0.30
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Maximum [Member] | Other Assets [Member] | Utilization Of Guaranteed Withdrawls [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	1.00
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Maximum [Member] | Other Assets [Member] | Claims Utilization Factor [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	1.00
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Maximum [Member] | Other Assets [Member] | Premiums Utilization Factor [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	1.15
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Maximum [Member] | Other Assets [Member] | NPR [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	0.0032
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Maximum [Member] | Other Assets [Member] | Volatility [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	0.29
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Indexed Annuity And Embedded Derivatives [Member] | Other Assets [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 44,000,000
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Indexed Annuity And Embedded Derivatives [Member] | Minimum [Member] | Other Assets [Member] | Long-Term Lapse Rate [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	0.01
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Indexed Annuity And Embedded Derivatives [Member] | Maximum [Member] | Other Assets [Member] | Long-Term Lapse Rate [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative assets, measurement input	0.09
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Future contract benefits - indexed annuity and IUL contracts embedded derivatives [Member] | Future Contract Benefits [Member]
Liabilities Fair Value Disclosure [Abstract]
Liabilities measured at fair value	$ (1,571,000,000)
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Future contract benefits - indexed annuity and IUL contracts embedded derivatives [Member] | Minimum [Member] | Future Contract Benefits [Member] | Long-Term Lapse Rate [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	0.01
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Future contract benefits - indexed annuity and IUL contracts embedded derivatives [Member] | Maximum [Member] | Future Contract Benefits [Member] | Long-Term Lapse Rate [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	0.09
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Other Liabilities [Member]
Liabilities Fair Value Disclosure [Abstract]
Liabilities measured at fair value	$ (193,000,000)
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Minimum [Member] | Other Liabilities [Member] | Long-Term Lapse Rate [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	0.01
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Minimum [Member] | Other Liabilities [Member] | Utilization Of Guaranteed Withdrawls [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	0.85
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Minimum [Member] | Other Liabilities [Member] | Claims Utilization Factor [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	0.60
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Minimum [Member] | Other Liabilities [Member] | Premiums Utilization Factor [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	0.80
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Minimum [Member] | Other Liabilities [Member] | NPR [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	0.0001
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Minimum [Member] | Other Liabilities [Member] | Volatility [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	0.01
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Maximum [Member] | Other Liabilities [Member] | Long-Term Lapse Rate [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	0.30
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Maximum [Member] | Other Liabilities [Member] | Utilization Of Guaranteed Withdrawls [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	1.00
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Maximum [Member] | Other Liabilities [Member] | Claims Utilization Factor [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	1.00
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Maximum [Member] | Other Liabilities [Member] | Premiums Utilization Factor [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	1.15
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Maximum [Member] | Other Liabilities [Member] | NPR [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	0.0032
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Maximum [Member] | Other Liabilities [Member] | Volatility [Member]
Liabilities Fair Value Disclosure [Abstract]
Derivative liability, measurement input	0.29