Fair Value of Financial Instruments (Fair Value Inputs Quantitative Information) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 243,199	$ 245,265
Liabilities Fair Value Disclosure [Abstract]
Liabilities measured at fair value	(2,400)	(3,689)
Significant Unobservable Inputs (Level 3) [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	5,455	5,197
Liabilities Fair Value Disclosure [Abstract]
Liabilities measured at fair value	(1,979)	$ (2,058)
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Corporate Bonds [Member] | Fixed Maturity AFS Securities [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 2,470
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Corporate Bonds [Member] | Maximum [Member] | Fixed Maturity AFS Securities [Member]
Assets Fair Value Disclosure [Abstract]
Liquidity Duration Adjustment	23.40%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Corporate Bonds [Member] | Minimum [Member] | Fixed Maturity AFS Securities [Member]
Assets Fair Value Disclosure [Abstract]
Liquidity Duration Adjustment	0.60%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | ABS [Member] | Fixed Maturity AFS Securities [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 23
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | ABS [Member] | Maximum [Member] | Fixed Maturity AFS Securities [Member]
Assets Fair Value Disclosure [Abstract]
Liquidity Duration Adjustment	3.00%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | ABS [Member] | Minimum [Member] | Fixed Maturity AFS Securities [Member]
Assets Fair Value Disclosure [Abstract]
Liquidity Duration Adjustment	3.00%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Foreign Government Bonds [Member] | Fixed Maturity AFS Securities [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 78
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Foreign Government Bonds [Member] | Maximum [Member] | Fixed Maturity AFS Securities [Member]
Assets Fair Value Disclosure [Abstract]
Liquidity Duration Adjustment	3.00%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Foreign Government Bonds [Member] | Minimum [Member] | Fixed Maturity AFS Securities [Member]
Assets Fair Value Disclosure [Abstract]
Liquidity Duration Adjustment	1.70%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Hybrid And Redeemable Preferred Securities [Member] | Fixed Maturity AFS Securities [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 4
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Hybrid And Redeemable Preferred Securities [Member] | Maximum [Member] | Fixed Maturity AFS Securities [Member]
Assets Fair Value Disclosure [Abstract]
Liquidity Duration Adjustment	1.80%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Hybrid And Redeemable Preferred Securities [Member] | Minimum [Member] | Fixed Maturity AFS Securities [Member]
Assets Fair Value Disclosure [Abstract]
Liquidity Duration Adjustment	1.80%
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
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Equity Securities [Member] | Maximum [Member]
Assets Fair Value Disclosure [Abstract]
Liquidity Duration Adjustment	5.30%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Equity Securities [Member] | Minimum [Member]
Assets Fair Value Disclosure [Abstract]
Liquidity Duration Adjustment	4.50%
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	$ 1,289
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Maximum [Member] | Other Assets [Member]
Fair Value Inputs [Abstract]
Lapse Rate	30.00%
Utilization of guaranteed withdrawals	100.00%
Claims Utilization Factor	100.00%
Premiums Utilization Factor	115.00%
NPR	0.31%
Volatility	29.00%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB direct and ceded embedded derivatives [Member] | Minimum [Member] | Other Assets [Member]
Fair Value Inputs [Abstract]
Lapse Rate	1.00%
Utilization of guaranteed withdrawals	85.00%
Claims Utilization Factor	60.00%
Premiums Utilization Factor	80.00%
NPR	0.02%
Volatility	1.00%
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	$ 29
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Indexed Annuity And Embedded Derivatives [Member] | Maximum [Member] | Other Assets [Member]
Fair Value Inputs [Abstract]
Lapse Rate	9.00%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Indexed Annuity And Embedded Derivatives [Member] | Minimum [Member] | Other Assets [Member]
Fair Value Inputs [Abstract]
Lapse Rate	1.00%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Future contract benefits - indexed annuity and IUL contracts embedded derivatives [Member]
Liabilities Fair Value Disclosure [Abstract]
Liabilities measured at fair value	$ (1,400)
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]
Fair Value Inputs [Abstract]
Lapse Rate	9.00%
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]
Fair Value Inputs [Abstract]
Lapse Rate	1.00%
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	$ (131)
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Maximum [Member] | Other Liabilities [Member]
Fair Value Inputs [Abstract]
Lapse Rate	30.00%
Utilization of guaranteed withdrawals	100.00%
Claims Utilization Factor	100.00%
Premiums Utilization Factor	115.00%
NPR	0.31%
Volatility	29.00%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | GLB Ceded Embedded Derivatives [Member] | Minimum [Member] | Other Liabilities [Member]
Fair Value Inputs [Abstract]
Lapse Rate	1.00%
Utilization of guaranteed withdrawals	85.00%
Claims Utilization Factor	60.00%
Premiums Utilization Factor	80.00%
NPR	0.02%
Volatility	1.00%