Derivatives (Effects on the Consolidated Statement of Operations and Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Net investment income	$ 5,314	$ 3,061
Net investment gains (losses)	134	(288)
Derivative, Gain (Loss) on Derivative, Net	(2,235)	4,201
Policyholder Benefits and Claims Incurred, Net	(10,523)	(9,022)
Policyholder Account Balance, Interest Expense	(1,351)	(80)
Operating Expenses	3,150	3,273
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net investment income	(15)	(4)
Net investment gains (losses)	0	0
Derivative, Gain (Loss) on Derivative, Net	(3,160)	5,476
Policyholder Benefits and Claims Incurred, Net	148	248
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net investment income	1	1
Net investment gains (losses)	(7)	(18)
Derivative, Gain (Loss) on Derivative, Net	0	0
Policyholder Benefits and Claims Incurred, Net	(29)	5
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net investment income	15	6
Net investment gains (losses)	21	8
Derivative, Gain (Loss) on Derivative, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	1	1
Other Comprehensive Income (Loss), before Tax	(1,268)	4,125
Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	56	108
Nonperformance Risk [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net	(43)	185
Foreign Exchange Forward [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax		110
Designated as Hedging Instrument [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	29
Interest Rate Contract | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net investment income	12	6
Net investment gains (losses)	29	6
Derivative, Gain (Loss) on Derivative, Net	0	0
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	1	1
Other Comprehensive Income (Loss), before Tax	(42)	(13)
Credit forwards [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net investment income	0	0
Net investment gains (losses)	0	0
Derivative, Gain (Loss) on Derivative, Net	0	0
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
Currency Swap [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net investment income	3	0
Net investment gains (losses)	(219)	(451)
Derivative, Gain (Loss) on Derivative, Net	0	0
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	216	451
Derivative [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net investment income	0	0
Net investment gains (losses)	(2)	(20)
Derivative, Gain (Loss) on Derivative, Net	0	0
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]
Net investment income	3	(11)
Net investment gains (losses)	0	0
Derivative, Gain (Loss) on Derivative, Net	0	0
Policyholder Benefits and Claims Incurred, Net	602	(774)
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]
Net investment income	13	72
Net investment gains (losses)	(128)	12
Derivative, Gain (Loss) on Derivative, Net	0	0
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Debt Securities [Member] | Interest rate swaps | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net investment income	(3)	5
Net investment gains (losses)	0	0
Derivative, Gain (Loss) on Derivative, Net	0	0
Policyholder Benefits and Claims Incurred, Net	573	(769)
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Debt Securities [Member] | Currency Swap [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net investment income	(12)	(65)
Net investment gains (losses)	123	(10)
Derivative, Gain (Loss) on Derivative, Net	0	0
Policyholder Benefits and Claims Incurred, Net	0	0
Policyholder Account Balance, Interest Expense	0	0
Operating Expenses	0	0
Non-derivative [Domain] [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	27	(2)
Foreign Currency Gain (Loss) [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net investment income	0	0
Net investment gains (losses)	211	453
Derivative, Gain (Loss) on Derivative, Net	0	0
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
Accumulated Other Comprehensive Income (Loss) | Credit forwards [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	(68)	62
Accumulated Other Comprehensive Income (Loss) | Currency Swap [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	(153)	1,614
Accumulated Other Comprehensive Income (Loss) | Interest rate swaps | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax	(1,221)	2,011
Foreign Exchange [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net investment income	0	0
Net investment gains (losses)	0	0
Derivative, Gain (Loss) on Derivative, Net	(483)	135
Policyholder Benefits and Claims Incurred, Net	3	(8)
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]
Net investment income	0	0
Net investment gains (losses)	0	0
Derivative, Gain (Loss) on Derivative, Net	19	73
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]
Net investment income	0	0
Net investment gains (losses)	0	0
Derivative, Gain (Loss) on Derivative, Net	5	(311)
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]
Net investment income	(17)	0
Net investment gains (losses)	0	0
Derivative, Gain (Loss) on Derivative, Net	(676)	1,559
Policyholder Benefits and Claims Incurred, Net	104	208
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]
Net investment income	2	(4)
Net investment gains (losses)	0	0
Derivative, Gain (Loss) on Derivative, Net	(2,250)	4,177
Policyholder Benefits and Claims Incurred, Net	47	(48)
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]
Net investment income	0	0
Net investment gains (losses)	0	0
Derivative, Gain (Loss) on Derivative, Net	225	(157)
Policyholder Benefits and Claims Incurred, Net	0	0
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]
Net investment income	39	77
Net investment gains (losses)	0	0
Derivative, Gain (Loss) on Derivative, Net	252	147
Policyholder Benefits and Claims Incurred, Net	(53)	(39)
Policyholder Account Balance, Interest Expense	(39)	(44)
Operating Expenses	0	0
Other Comprehensive Income (Loss), before Tax	0	0
Net Embedded Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	673	(1,422)
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	40	80
Net investment gains (losses)	14	(10)
Policyholder Benefits and Claims Incurred, Net	124	(292)
Policyholder Account Balance, Interest Expense	39	44
Operating Expenses	1	1
Other Comprehensive Income (Loss), before Tax	$ (1,212)	$ 4,233