Fair Value of Financial Instruments (Fair Value of Assets and Liabilities on a Recurring Basis) (Details) - USD ($) $ in Millions		Jun. 30, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		$ 235,024	$ 224,673
Liabilities measured at fair value		(3,292)	(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		1,639	1,596
Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		229,377	219,330
Liabilities measured at fair value		(1,608)	(2,195)
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		4,008	3,747
Liabilities measured at fair value		(1,684)	(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		80,548	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		78,031	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		2,517	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		1,050	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		1,007	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		43	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		578	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		564	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		455	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		109	111
RMBS [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		3,552	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		3,545	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		476	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		455	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		21	7
CLOs [Member] | Fixed maturity AFS securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		703	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		675	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		28	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		5,010	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		5,010	4,627
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		642	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		67	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		493	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		82	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		275	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		13	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		79	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		183	177
Trading securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		1,678	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		73	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		1,546	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		59	65
Derivative investments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value	[1]	1,721	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]	1,150	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]	571	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		1,978	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		1,978	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		85	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		85	203
Separate Account Assets [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		135,825	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		772	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		135,053	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		(1,268)	(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		(1,268)	(1,139)
Long-term Debt [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value		(1,135)	(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		(1,135)	(1,203)
Reinsurance related embedded derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value		(53)	(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		(53)	(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]	(836)	(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]	(420)	(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]	(416)	(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		298
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		$ 298
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.