Derivatives Derivatives (Effects on the Consolidated Statement of Operations and Comprehensive Income (Loss)) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 628,000,000	$ 851,000,000	$ (590,000,000)
Net Investment Income	18,868,000,000	16,166,000,000	17,363,000,000
Net investment gains (losses)	444,000,000	(298,000,000)	(308,000,000)
Policyholder benefits and claims	41,461,000,000	42,656,000,000	38,313,000,000
Policyholder Account Balance, Interest Expense	6,464,000,000	4,013,000,000	5,607,000,000
Operating Expenses	13,689,000,000	13,714,000,000	13,621,000,000
Other Comprehensive Income (Loss), before Tax	14,639,000,000	(8,369,000,000)	4,369,000,000
Nonperformance Risk [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net	(116,000,000)	133,000,000	(190,000,000)
Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(46,000,000)	50,000,000
Net Investment Income	2,000,000	0	0
Net investment gains (losses)	(71,000,000)	0	0
Policyholder benefits and claims	(30,000,000)	0	0
Policyholder Account Balance, Interest Expense	1,000,000	0	0
Operating Expenses	0	0	0
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	33,000,000	28,000,000
Net Investment Income	20,000,000	16,000,000	18,000,000
Net investment gains (losses)	8,000,000	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	4,000,000	3,000,000	3,000,000
Other Comprehensive Income (Loss), before Tax	82,000,000	674,000,000	(1,056,000,000)
Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	(36,000,000)	(125,000,000)	(445,000,000)
Foreign Exchange Forward [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax		(125,000,000)	(445,000,000)
Designated as Hedging Instrument [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	(32,000,000)
Interest Rate Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	21,000,000	13,000,000
Net Investment Income	23,000,000	20,000,000	18,000,000
Net investment gains (losses)	4,000,000	0	0
Policyholder benefits and claims	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	2,000,000	1,000,000	1,000,000
Other Comprehensive Income (Loss), before Tax	(29,000,000)	(42,000,000)	(32,000,000)
Credit forwards [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	1,000,000	1,000,000
Net Investment Income	1,000,000	1,000,000	0
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	0	0	0
Other Comprehensive Income (Loss), before Tax	(1,000,000)	(2,000,000)	(1,000,000)
Currency Swap [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(558,000,000)	974,000,000
Net Investment Income	(4,000,000)	(5,000,000)	0
Net investment gains (losses)	240,000,000	0	0
Policyholder benefits and claims	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	2,000,000	2,000,000	2,000,000
Other Comprehensive Income (Loss), before Tax	(238,000,000)	561,000,000	(976,000,000)
Derivative [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(58,000,000)	(40,000,000)
Net Investment Income	0	0	0
Net investment gains (losses)	(72,000,000)	0	0
Policyholder benefits and claims	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	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	(220,000,000)	(65,000,000)
Net Investment Income	(3,000,000)	0	0
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	339,000,000	0	0
Policyholder Account Balance, Interest Expense	1,000,000	0	0
Operating Expenses	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	156,000,000	51,000,000
Net Investment Income	(55,000,000)	0	0
Net investment gains (losses)	24,000,000	0	0
Policyholder benefits and claims	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	0	0	0
Debt Securities [Member] | Interest rate swaps | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	226,000,000	130,000,000
Net Investment Income	4,000,000	0	0
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	(369,000,000)	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	0	0	0
Debt Securities [Member] | Currency Swap [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(150,000,000)	(26,000,000)
Net Investment Income	56,000,000	0	0
Net investment gains (losses)	(23,000,000)	0	0
Policyholder benefits and claims	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	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	569,000,000	(960,000,000)
Net Investment Income	0	0	0
Net investment gains (losses)	(236,000,000)	0	0
Policyholder benefits and claims	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	0	0	0
Other Comprehensive Income (Loss), before Tax	0	0	0
Non-derivative [Domain] [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	(4,000,000)	0	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	6,000,000	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	(278,000,000)	414,000,000	(335,000,000)
Accumulated Other Comprehensive Income (Loss) | Interest rate swaps | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	622,000,000	(257,000,000)	288,000,000
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(157,000,000)	467,000,000	(2,018,000,000)
Net Investment Income	(3,000,000)	5,000,000	(8,000,000)
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	(164,000,000)	48,000,000	(248,000,000)
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	0	0	0
Foreign Exchange [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(346,000,000)	518,000,000	(742,000,000)
Net Investment Income	0	0	0
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	2,000,000	(6,000,000)	5,000,000
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	0	0	0
Credit derivatives — purchased | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(38,000,000)	6,000,000	(24,000,000)
Net Investment Income	0	0	0
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	0	0	0
Credit derivatives — written | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	248,000,000	(132,000,000)	145,000,000
Net Investment Income	0	0	0
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	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	(1,339,000,000)	360,000,000	(1,046,000,000)
Net Investment Income	0	1,000,000	(9,000,000)
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	(205,000,000)	60,000,000	(252,000,000)
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	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	55,000,000	(127,000,000)	198,000,000
Net Investment Income	0	0	0
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	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	1,263,000,000	(158,000,000)	(549,000,000)
Net Investment Income	(3,000,000)	4,000,000	1,000,000
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	39,000,000	(6,000,000)	(1,000,000)
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	0	0	0
Nonoperating Income (Expense) [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	513,000,000	547,000,000	551,000,000
Net Investment Income	237,000,000	360,000,000	299,000,000
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	138,000,000	11,000,000	9,000,000
Policyholder Account Balance, Interest Expense	(147,000,000)	(113,000,000)	(64,000,000)
Operating Expenses	0	(11,000,000)	(10,000,000)
Other Comprehensive Income (Loss), before Tax	0	0	0
Embedded Derivative Financial Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	272,000,000	(150,000,000)	799,000,000
Policyholder benefits and claims	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	256,000,000	381,000,000	309,000,000
Net investment gains (losses)	(63,000,000)	0	0
Policyholder benefits and claims	(56,000,000)	59,000,000	(239,000,000)
Policyholder Account Balance, Interest Expense	(146,000,000)	(113,000,000)	(64,000,000)
Operating Expenses	4,000,000	(8,000,000)	(7,000,000)
Other Comprehensive Income (Loss), before Tax	$ 46,000,000	$ 549,000,000	$ (1,501,000,000)