Derivatives (Effects on the Consolidated Statement of Operations and Comprehensive Income (Loss)) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 4,201,000,000	$ 115,000,000
Net Investment Income	3,061,000,000	4,908,000,000
Gain (Loss) on Investments	(288,000,000)	15,000,000
Policyholder Benefits and Claims Incurred, Net	9,022,000,000	9,072,000,000
Policyholder Account Balance, Interest Expense	80,000,000	1,961,000,000
Operating Expenses	3,273,000,000	3,225,000,000
Nonperformance Risk [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net	185,000,000	(62,000,000)
Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0
Net Investment Income	1,000,000	(1,000,000)
Gain (Loss) on Investments	(18,000,000)	(18,000,000)
Policyholder Benefits and Claims Incurred, Net	5,000,000	(1,000,000)
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0
Net Investment Income	6,000,000	3,000,000
Gain (Loss) on Investments	8,000,000	(15,000,000)
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	1,000,000	1,000,000
Other Comprehensive Income (Loss), before Tax	4,125,000,000	(13,000,000)
Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	108,000,000	(6,000,000)
Foreign Exchange Forward [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax		(6,000,000)
Designated as Hedging Instrument [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	110,000,000
Interest Rate Contract | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0
Net Investment Income	6,000,000	5,000,000
Gain (Loss) on Investments	6,000,000	(6,000,000)
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	1,000,000	1,000,000
Other Comprehensive Income (Loss), before Tax	(13,000,000)	0
Credit forwards [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0
Net Investment Income	0	0
Gain (Loss) on Investments	0	1,000,000
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Other Comprehensive Income (Loss), before Tax	0	(1,000,000)
Currency Swap [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0
Net Investment Income	0	(2,000,000)
Gain (Loss) on Investments	(451,000,000)	25,000,000
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Other Comprehensive Income (Loss), before Tax	451,000,000	(23,000,000)
Derivative [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0
Net Investment Income	0	0
Gain (Loss) on Investments	(20,000,000)	(16,000,000)
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	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
Net Investment Income	(11,000,000)	(3,000,000)
Gain (Loss) on Investments	0	0
Policyholder Benefits and Claims Incurred, Net	774,000,000	127,000,000
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	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
Net Investment Income	72,000,000	(30,000,000)
Gain (Loss) on Investments	12,000,000	(14,000,000)
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Debt Securities | Interest rate swaps | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0
Net Investment Income	5,000,000	3,000,000
Gain (Loss) on Investments	0	0
Policyholder Benefits and Claims Incurred, Net	(769,000,000)	(128,000,000)
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Debt Securities | Currency Swap [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0
Net Investment Income	(65,000,000)	29,000,000
Gain (Loss) on Investments	(10,000,000)	12,000,000
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	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
Net Investment Income	0	0
Gain (Loss) on Investments	453,000,000	(35,000,000)
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Other Comprehensive Income (Loss), before Tax	0	0
Non-derivative [Domain] [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	(2,000,000)	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	62,000,000	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	1,614,000,000	(241,000,000)
Accumulated Other Comprehensive Income (Loss) | Interest rate swaps | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	2,011,000,000	252,000,000
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	5,476,000,000	(197,000,000)
Net Investment Income	(4,000,000)	(1,000,000)
Gain (Loss) on Investments	0	0
Policyholder Benefits and Claims Incurred, Net	248,000,000	(74,000,000)
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Foreign Exchange [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	135,000,000	(142,000,000)
Net Investment Income	0	0
Gain (Loss) on Investments	0	0
Policyholder Benefits and Claims Incurred, Net	(8,000,000)	3,000,000
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Credit derivatives — purchased | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	73,000,000	(15,000,000)
Net Investment Income	0	0
Gain (Loss) on Investments	0	0
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Credit derivatives — written | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(311,000,000)	136,000,000
Net Investment Income	0	0
Gain (Loss) on Investments	0	0
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Equity Market Risk [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	1,559,000,000	(667,000,000)
Net Investment Income	0	0
Gain (Loss) on Investments	0	0
Policyholder Benefits and Claims Incurred, Net	208,000,000	(96,000,000)
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	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	(157,000,000)	82,000,000
Net Investment Income	0	0
Gain (Loss) on Investments	0	0
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Interest Rate Risk [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	4,177,000,000	409,000,000
Net Investment Income	(4,000,000)	(1,000,000)
Gain (Loss) on Investments	0	0
Policyholder Benefits and Claims Incurred, Net	48,000,000	19,000,000
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	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	147,000,000	119,000,000
Net Investment Income	77,000,000	56,000,000
Gain (Loss) on Investments	0	0
Policyholder Benefits and Claims Incurred, Net	39,000,000	32,000,000
Policyholder Account Balance, Interest Expense	(44,000,000)	(32,000,000)
Operating Expenses	0	0
Other Comprehensive Income (Loss), before Tax	0	0
Embedded Derivative Financial Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1,422,000,000)	193,000,000
Policyholder Benefits and Claims Incurred, Net	0	0
Effects of Derivatives on Consolidated Statements of Operations and Comprehensive Income (Loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Investment Income	80,000,000	57,000,000
Gain (Loss) on Investments	(10,000,000)	(33,000,000)
Policyholder Benefits and Claims Incurred, Net	292,000,000	(43,000,000)
Policyholder Account Balance, Interest Expense	(44,000,000)	(32,000,000)
Operating Expenses	1,000,000	1,000,000
Other Comprehensive Income (Loss), before Tax	$ 4,233,000,000	$ (19,000,000)