Fair Value of Financial Instruments (Fair Value Inputs Quantitative Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 245,265	$ 224,673
Liabilities Fair Value Disclosure [Abstract]
Liabilities measured at fair value	(3,689)	(4,397)
Significant Unobservable Inputs (Level 3) [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	5,197	3,747
Liabilities Fair Value Disclosure [Abstract]
Liabilities measured at fair value	$ (2,058)	$ (2,202)
Significant Unobservable Inputs (Level 3) [Member] | GLB Ceded Embedded Derivatives [Member] | Maximum [Member] | Other liabilities [Member]
Fair Value Inputs [Abstract]
Utilization of guaranteed withdrawal	100.00%
Claims Utilization Factor	100.00%
Premiums Utilization Factor	115.00%
NPR	0.25%
Volatility	29.00%
Significant Unobservable Inputs (Level 3) [Member] | GLB Ceded Embedded Derivatives [Member] | Minimum [Member] | Other liabilities [Member]
Fair Value Inputs [Abstract]
Utilization of guaranteed withdrawal	85.00%
Claims Utilization Factor	60.00%
Premiums Utilization Factor	80.00%
NPR	0.01%
Volatility	1.00%
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	$ 2,411
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	21.00%
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	0.50%
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	$ 24
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	3.40%
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 AFS securities [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 22
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Equity AFS securities [Member] | Maximum [Member]
Assets Fair Value Disclosure [Abstract]
Liquidity Duration Adjustment	4.90%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Equity AFS 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	$ 954
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 withdrawal	100.00%
Claims Utilization Factor	100.00%
Premiums Utilization Factor	115.00%
NPR	0.25%
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 withdrawal	85.00%
Claims Utilization Factor	60.00%
Premiums Utilization Factor	80.00%
NPR	0.01%
Volatility	1.00%
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Indexed annuity and embedded derivatives [Member]
Assets Fair Value Disclosure [Abstract]
Assets Fair Value Disclosure	$ 11
Significant Unobservable Inputs (Level 3) [Member] | Discounted Cash Flow Valuation Technique [Member] | Indexed annuity and 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] | Indexed annuity and 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] | 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	$ (1,418)
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]
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] | Future contract benefits [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	$ (67)
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%
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%