Derivatives (Effects on the Consolidated Statement of Operations and Comprehensive Income (Loss)) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 724,000,000	$ (59,000,000)	$ 839,000,000	$ 290,000,000
Net Investment Income	4,693,000,000	4,473,000,000	9,601,000,000	8,218,000,000
Gain (Loss) on Investments	61,000,000	(227,000,000)	76,000,000	(560,000,000)
Policyholder Benefits and Claims Incurred, Net	9,993,000,000	14,866,000,000	19,065,000,000	23,584,000,000
Policyholder Account Balance, Interest Expense	1,515,000,000	1,424,000,000	3,476,000,000	2,193,000,000
Operating Expenses	3,390,000,000	3,485,000,000	6,615,000,000	6,850,000,000
Nonperformance Risk [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net	(13,000,000)	(25,000,000)	(75,000,000)	(5,000,000)
Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(16,000,000)	0	(13,000,000)
Net Investment Income	0	0	(1,000,000)	0
Gain (Loss) on Investments	(17,000,000)	0	(35,000,000)	0
Policyholder Benefits and Claims Incurred, Net	(1,000,000)	0	(2,000,000)	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	2,000,000	0	24,000,000
Net Investment Income	5,000,000	5,000,000	8,000,000	9,000,000
Gain (Loss) on Investments	(4,000,000)	0	(19,000,000)	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	1,000,000	1,000,000	2,000,000	2,000,000
Other Comprehensive Income (Loss), before Tax	566,000,000	611,000,000	553,000,000	94,000,000
Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	(44,000,000)	81,000,000	(50,000,000)	(76,000,000)
Foreign Exchange Forward [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax				(76,000,000)
Designated as Hedging Instrument [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	(37,000,000)	81,000,000	(43,000,000)
Interest Rate Contract | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(1,000,000)	0	20,000,000
Net Investment Income	6,000,000	6,000,000	11,000,000	10,000,000
Gain (Loss) on Investments	4,000,000	0	(2,000,000)	0
Policyholder Benefits and Claims Incurred, Net	0	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	1,000,000	1,000,000	1,000,000
Other Comprehensive Income (Loss), before Tax	(10,000,000)	(6,000,000)	(10,000,000)	(31,000,000)
Credit forwards [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Net Investment Income	0	0	0	0
Gain (Loss) on Investments	(1,000,000)	0	0	0
Policyholder Benefits and Claims Incurred, Net	0	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Other Comprehensive Income (Loss), before Tax	1,000,000	0	0	0
Currency Swap [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(475,000,000)	0	(336,000,000)
Net Investment Income	(1,000,000)	(1,000,000)	(3,000,000)	(1,000,000)
Gain (Loss) on Investments	83,000,000	0	108,000,000	0
Policyholder Benefits and Claims Incurred, Net	0	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	1,000,000	0	1,000,000	1,000,000
Other Comprehensive Income (Loss), before Tax	(83,000,000)	476,000,000	(106,000,000)	336,000,000
Derivative [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(12,000,000)	0	(20,000,000)
Net Investment Income	0	0	0	0
Gain (Loss) on Investments	(22,000,000)	0	(38,000,000)	0
Policyholder Benefits and Claims Incurred, Net	0	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Derivative [Member] | Interest rate swaps | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(68,000,000)	0	(278,000,000)
Net Investment Income	(1,000,000)	0	(4,000,000)	0
Gain (Loss) on Investments	0	0	0	0
Policyholder Benefits and Claims Incurred, Net	205,000,000	0	332,000,000	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Derivative [Member] | Currency Swap [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(57,000,000)	0	113,000,000
Net Investment Income	10,000,000	0	(20,000,000)	0
Gain (Loss) on Investments	59,000,000	0	45,000,000	0
Policyholder Benefits and Claims Incurred, Net	0	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Debt Securities | Interest rate swaps | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	70,000,000	0	280,000,000
Net Investment Income	2,000,000	0	5,000,000	0
Gain (Loss) on Investments	0	0	0	0
Policyholder Benefits and Claims Incurred, Net	(206,000,000)	0	(334,000,000)	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Debt Securities | Currency Swap [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	51,000,000	0	(108,000,000)
Net Investment Income	(11,000,000)	0	18,000,000	0
Gain (Loss) on Investments	(54,000,000)	0	(42,000,000)	0
Policyholder Benefits and Claims Incurred, Net	0	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Foreign Currency Gain (Loss) [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	478,000,000	0	340,000,000
Net Investment Income	0	0	0	0
Gain (Loss) on Investments	(90,000,000)	0	(125,000,000)	0
Policyholder Benefits and Claims Incurred, Net	0	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Other Comprehensive Income (Loss), before Tax	0	0	0	0
Non-derivative [Domain] [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	(7,000,000)	0	(7,000,000)	0
Accumulated Other Comprehensive Income (Loss) | Credit forwards [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	0	0	0	0
Accumulated Other Comprehensive Income (Loss) | Currency Swap [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	300,000,000	198,000,000	59,000,000	123,000,000
Accumulated Other Comprehensive Income (Loss) | Interest rate swaps | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	358,000,000	(57,000,000)	610,000,000	(334,000,000)
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	745,000,000	(329,000,000)	548,000,000	(175,000,000)
Net Investment Income	(1,000,000)	0	(2,000,000)	5,000,000
Gain (Loss) on Investments	0	0	0	0
Policyholder Benefits and Claims Incurred, Net	(22,000,000)	(43,000,000)	(96,000,000)	(36,000,000)
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Foreign Exchange [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	136,000,000	(1,000,000)	(6,000,000)	386,000,000
Net Investment Income	0	0	0	0
Gain (Loss) on Investments	0	0	0	0
Policyholder Benefits and Claims Incurred, Net	(4,000,000)	(5,000,000)	(1,000,000)	(3,000,000)
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Credit derivatives — purchased | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(5,000,000)	14,000,000	(20,000,000)	11,000,000
Net Investment Income	0	0	0	0
Gain (Loss) on Investments	0	0	0	0
Policyholder Benefits and Claims Incurred, Net	0	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Credit derivatives — written | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	50,000,000	(35,000,000)	186,000,000	(79,000,000)
Net Investment Income	0	0	0	0
Gain (Loss) on Investments	0	0	0	0
Policyholder Benefits and Claims Incurred, Net	0	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Equity Market Risk [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(182,000,000)	(174,000,000)	(849,000,000)	(76,000,000)
Net Investment Income	0	0	0	1,000,000
Gain (Loss) on Investments	0	0	0	0
Policyholder Benefits and Claims Incurred, Net	(30,000,000)	(33,000,000)	(126,000,000)	(21,000,000)
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Foreign Currency Gain (Loss) [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(111,000,000)	(58,000,000)	(29,000,000)	(107,000,000)
Net Investment Income	0	0	0	0
Gain (Loss) on Investments	0	0	0	0
Policyholder Benefits and Claims Incurred, Net	0	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Interest Rate Risk [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	857,000,000	(75,000,000)	1,266,000,000	(310,000,000)
Net Investment Income	(1,000,000)	0	(2,000,000)	4,000,000
Gain (Loss) on Investments	0	0	0	0
Policyholder Benefits and Claims Incurred, Net	12,000,000	(5,000,000)	31,000,000	(12,000,000)
Policyholder Account Balance, Interest Expense	0	0	0	0
Operating Expenses	0	0	0	0
Net Derivative Gain (Loss) [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	125,000,000	133,000,000	244,000,000	266,000,000
Net Investment Income	60,000,000	93,000,000	116,000,000	174,000,000
Gain (Loss) on Investments	0	0	0	0
Policyholder Benefits and Claims Incurred, Net	33,000,000	3,000,000	65,000,000	5,000,000
Policyholder Account Balance, Interest Expense	(36,000,000)	(28,000,000)	(68,000,000)	(51,000,000)
Operating Expenses	0	(4,000,000)	0	(6,000,000)
Other Comprehensive Income (Loss), before Tax	0	0	0	0
Embedded Derivative Financial Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(146,000,000)	151,000,000	47,000,000	188,000,000
Policyholder Benefits and Claims Incurred, Net	0	0	0	0
Effects of Derivatives on Consolidated Statements of Operations and Comprehensive Income (Loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Investment Income	64,000,000	98,000,000	121,000,000	188,000,000
Gain (Loss) on Investments	(21,000,000)	0	(54,000,000)	0
Policyholder Benefits and Claims Incurred, Net	10,000,000	(40,000,000)	(33,000,000)	(31,000,000)
Policyholder Account Balance, Interest Expense	(36,000,000)	(28,000,000)	(68,000,000)	(51,000,000)
Operating Expenses	1,000,000	(3,000,000)	2,000,000	(4,000,000)
Other Comprehensive Income (Loss), before Tax	$ 522,000,000	$ 692,000,000	$ 503,000,000	$ 18,000,000