Derivatives Derivatives (Effects on the Consolidated Statement of Operations and Comprehensive Income (Loss)) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 1,349,000,000	$ 628,000,000	$ 851,000,000
Net investment income	17,117,000,000	18,868,000,000	16,166,000,000
Net investment gains (losses)	(110,000,000)	444,000,000	(298,000,000)
Policyholder benefits and claims	(41,461,000,000)	(41,461,000,000)	(42,656,000,000)
Policyholder Account Balance, Interest Expense	(5,214,000,000)	(6,464,000,000)	(4,013,000,000)
Operating Expenses	13,150,000,000	13,689,000,000	13,714,000,000
Other Comprehensive Income (Loss), before Tax	6,262,000,000	14,639,000,000	(8,369,000,000)
Nonperformance Risk [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net	(10,000,000)	(116,000,000)	133,000,000
Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	(46,000,000)
Net investment income	0	2,000,000	0
Net investment gains (losses)	(42,000,000)	(71,000,000)	0
Policyholder benefits and claims	(39,000,000)	(30,000,000)	0
Policyholder Account Balance, Interest Expense	0	(1,000,000)	0
Operating Expenses	0	0	0
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	33,000,000
Net investment income	40,000,000	20,000,000	16,000,000
Net investment gains (losses)	207,000,000	8,000,000	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	4,000,000	4,000,000	3,000,000
Other Comprehensive Income (Loss), before Tax	(286,000,000)	82,000,000	674,000,000
Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	16,000,000	(36,000,000)	(125,000,000)
Foreign Exchange Forward [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax		(32,000,000)	(125,000,000)
Designated as Hedging Instrument [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	36,000,000
Interest Rate Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	21,000,000
Net investment income	36,000,000	23,000,000	20,000,000
Net investment gains (losses)	121,000,000	4,000,000	0
Policyholder benefits and claims	0	0	0
Policyholder Account Balance, Interest Expense	0	0	0
Operating Expenses	2,000,000	2,000,000	1,000,000
Other Comprehensive Income (Loss), before Tax	(159,000,000)	(29,000,000)	(42,000,000)
Credit forwards [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	1,000,000
Net investment income	0	1,000,000	1,000,000
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	0	(1,000,000)	(2,000,000)
Currency Swap [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	(558,000,000)
Net investment income	4,000,000	(4,000,000)	(5,000,000)
Net investment gains (losses)	851,000,000	240,000,000	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	(857,000,000)	(238,000,000)	561,000,000
Derivative [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	(58,000,000)
Net investment income	0	0	0
Net investment gains (losses)	(47,000,000)	(72,000,000)	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	0	(220,000,000)
Net investment income	(10,000,000)	(3,000,000)	0
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	(360,000,000)	(339,000,000)	0
Policyholder Account Balance, Interest Expense	0	(1,000,000)	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	0	156,000,000
Net investment income	(46,000,000)	(55,000,000)	0
Net investment gains (losses)	98,000,000	24,000,000	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	0	226,000,000
Net investment income	12,000,000	4,000,000	0
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	(399,000,000)	(369,000,000)	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	0	(150,000,000)
Net investment income	44,000,000	56,000,000	0
Net investment gains (losses)	(93,000,000)	(23,000,000)	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	0	569,000,000
Net investment income	0	0	0
Net investment gains (losses)	(765,000,000)	(236,000,000)	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	(20,000,000)	(4,000,000)	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	(102,000,000)	6,000,000	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	(445,000,000)	(278,000,000)	414,000,000
Accumulated Other Comprehensive Income (Loss) | Interest rate swaps | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	1,277,000,000	622,000,000	(257,000,000)
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	533,000,000	(157,000,000)	467,000,000
Net investment income	(34,000,000)	(3,000,000)	5,000,000
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	(151,000,000)	(164,000,000)	(48,000,000)
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	(323,000,000)	(346,000,000)	518,000,000
Net investment income	0	0	0
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	(3,000,000)	(2,000,000)	(6,000,000)
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	(28,000,000)	(38,000,000)	6,000,000
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	(106,000,000)	248,000,000	(132,000,000)
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	(1,151,000,000)	(1,339,000,000)	360,000,000
Net investment income	(28,000,000)	0	1,000,000
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	(203,000,000)	(205,000,000)	(60,000,000)
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	(8,000,000)	55,000,000	(127,000,000)
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	2,149,000,000	1,263,000,000	(158,000,000)
Net investment income	(6,000,000)	(3,000,000)	4,000,000
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	(55,000,000)	(39,000,000)	(6,000,000)
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	926,000,000	513,000,000	547,000,000
Net investment income	217,000,000	237,000,000	360,000,000
Net investment gains (losses)	0	0	0
Policyholder benefits and claims	(190,000,000)	(138,000,000)	(11,000,000)
Policyholder Account Balance, Interest Expense	(152,000,000)	(147,000,000)	(113,000,000)
Operating Expenses	0	0	(11,000,000)
Other Comprehensive Income (Loss), before Tax	0	0	0
Net Embedded Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(110,000,000)	272,000,000	(150,000,000)
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	223,000,000	256,000,000	381,000,000
Net investment gains (losses)	165,000,000	(63,000,000)	0
Policyholder benefits and claims	0	56,000,000	(59,000,000)
Policyholder Account Balance, Interest Expense	152,000,000	146,000,000	113,000,000
Operating Expenses	4,000,000	4,000,000	(8,000,000)
Other Comprehensive Income (Loss), before Tax	$ (270,000,000)	$ 46,000,000	$ 549,000,000