Fair Value of Financial Instruments (Fair Value of Assets and Liabilities on a Recurring Basis) (Details) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		$ 260,798	$ 233,897
Liabilities measured at fair value		(4,653)	(1,793)
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		1,319	1,340
Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		252,069	227,067
Liabilities measured at fair value		(1,180)	(317)
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		7,410	5,490
Liabilities measured at fair value		(3,473)	(1,476)
Corporate Bonds [Member] | Fixed Maturity AFS Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		87,911	80,348
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		84,002	77,079
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		3,909	3,269
ABS [Member] | Fixed Maturity AFS Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		4,172	2,696
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		3,955	2,562
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		217	134
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		438	417
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		421	399
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		17	18
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		444	448
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		329	339
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		115	109
RMBS [Member] | Fixed Maturity AFS Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		3,287	3,373
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		3,277	3,366
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		10	7
CMBS [Member] | Fixed Maturity AFS Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		1,032	804
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		1,023	802
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		9	2
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		5,800	5,345
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		5,800	5,345
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		575	593
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		77	67
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		420	451
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		78	75
Trading Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		4,691	1,950
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		50	43
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		4,075	1,840
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		566	67
Equity Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		158	99
Equity 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		47	16
Equity Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		57	58
Equity Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		54	25
Derivative Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value	[1]	2,987	1,432
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]	1,667	727
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]	1,320	705
Other Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		153	150
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		153	150
Cash And Invested Cash [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		2,939	2,345
Cash And 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		2,939	2,345
GLB Direct Embedded Derivatives [Member] | Other Assets [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value			123
GLB Direct Embedded Derivatives [Member] | Other Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value		(846)
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			123
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		(846)
GLB Ceded Embedded Derivatives [Member] | Other Assets [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		241	72
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		241	72
Indexed Annuity And IUL Contracts [Member] | Other Assets [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		891	902
Indexed Annuity And IUL Contracts [Member] | Future Contract Benefits [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value		(2,098)	(1,305)
Indexed Annuity And IUL Contracts [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		891	902
Indexed Annuity And IUL Contracts [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		(2,098)	(1,305)
Separate Account Assets [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets measured at fair value		145,079	132,800
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		571	665
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		144,508	132,135
Reinsurance Related Embedded Derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value		(339)	(3)
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		(339)	(3)
Derivative Liabilities [Member] | Other Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities measured at fair value	[1]	(1,370)	(485)
Derivative 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]	(841)	(314)
Derivative 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]	$ (529)	$ (171)

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