Fair Value of Financial Instruments (Fair Value of Assets and Liabilities on a Recurring Basis) (Details) - USD ($) $ in Millions		Mar. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		$ 230,091	$ 224,673
Liabilities measured at fair value		(3,223)	(4,397)
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		1,730	1,596
Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		224,451	219,330
Liabilities measured at fair value		(1,537)	(2,195)
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		3,910	3,747
Liabilities measured at fair value		(1,686)	(2,202)
Corporate bonds [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		78,779	77,064
Corporate bonds [Member] | Significant Observable Inputs (Level 2) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		76,376	74,659
Corporate bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		2,403	2,405
ABS [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		1,062	1,085
ABS [Member] | Significant Observable Inputs (Level 2) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		1,033	1,052
ABS [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		29	33
U.S. government bonds [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		576	419
U.S. government bonds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		562	408
U.S. government bonds [Member] | Significant Observable Inputs (Level 2) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		9	11
U.S. government bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		5
Foreign government bonds [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		456	506
Foreign government bonds [Member] | Significant Observable Inputs (Level 2) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		346	395
Foreign government bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		110	111
RMBS [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		3,581	3,614
RMBS [Member] | Significant Observable Inputs (Level 2) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		3,574	3,611
RMBS [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		7	3
CMBS [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		427	350
CMBS [Member] | Significant Observable Inputs (Level 2) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		383	343
CMBS [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		44	7
CLOs [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		776	744
CLOs [Member] | Significant Observable Inputs (Level 2) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		688	676
CLOs [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		88	68
State and municipal bonds [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		4,826	4,627
State and municipal bonds [Member] | Significant Observable Inputs (Level 2) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		4,825	4,627
State and municipal bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		1
Hybrid and redeemable preferred securities [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		619	604
Hybrid and redeemable preferred securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		66	60
Hybrid and redeemable preferred securities [Member] | Significant Observable Inputs (Level 2) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		474	468
Hybrid and redeemable preferred securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		79	76
VIEs' fixed maturity securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value			200
VIEs' fixed maturity securities [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value			200
Equity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		276	275
Equity AFS securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		16	17
Equity AFS securities [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		78	81
Equity AFS securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		182	177
Trading securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		1,703	1,712
Trading securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		102	102
Trading securities [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		1,541	1,545
Trading securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		60	65
Derivative investments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value	[1]	1,637	2,005
Derivative investments [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value	[1]	1,077	1,406
Derivative investments [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value	[1]	560	599
Other investments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		150	146
Other investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		150	146
Invested cash [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		1,923	2,722
Invested cash [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		1,923	2,722
GLB ceded embedded derivatives [Member] | Other assets [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		116	203
GLB ceded embedded derivatives [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other assets [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		116	203
Separate Account Assets [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		132,958	128,397
Separate Account Assets [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		834	863
Separate Account Assets [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		132,124	127,534
Indexed annuity and IUL contracts embedded derivatives [Member] | Future contract benefits [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value		(1,238)	(1,139)
Indexed annuity and IUL contracts embedded derivatives [Member] | Significant Unobservable Inputs (Level 3) [Member] | Future contract benefits [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value		(1,238)	(1,139)
Long-term Debt [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value		(1,118)	(1,203)
Long-term Debt [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value		(1,118)	(1,203)
Reinsurance related embedded derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value		(50)	(53)
Reinsurance related embedded derivatives [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value		(50)	(53)
Derivative Financial Instruments, Liabilities [Member] | Other liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value	[1]	(817)	(1,631)
Derivative Financial Instruments, Liabilities [Member] | Significant Observable Inputs (Level 2) [Member] | Other liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value	[1]	(369)	(939)
Derivative Financial Instruments, Liabilities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value	[1]	(448)	(692)
GLB direct embedded derivatives [Member] | Other assets [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		226
GLB direct embedded derivatives [Member] | Other liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value			(371)
GLB direct embedded derivatives [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other assets [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		$ 226
GLB direct embedded derivatives [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value			$ (371)

[1] Derivative investment assets and liabilities presented within the fair value hierarchy are presented on a gross basis by derivative type and not on a master netting basis by counterparty.