Shareholders' Equity, Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 19,181	$ 21,930	$ 21,386
Other comprehensive income (loss)	(445)	727	911
Amounts attributable to noncontrolling interests
Balance at end of period	19,175	19,181	21,930
Net Unrealized Gains (Losses) on Investments with OTTI Losses
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	0	13
Other comprehensive income (loss) before reclassifications, after tax	(7)	(43)	(13)
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	5	43	12
Other comprehensive income (loss)	(2)	0	(1)
Amounts attributable to noncontrolling interests
Balance at end of period	(2)	0	13
Other Comprehensive Income (Loss) before Reclassifications, Tax	2	12	3
Reclassification from AOCI, Current Period, Tax	(1)	(12)	(3)
Net Other Unrealized Gains (Losses) on Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	1,563	905
Other comprehensive income (loss) before reclassifications, after tax	(625)	763	957
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	(81)	(43)	(8)
Other comprehensive income (loss)	(706)	720	949
Amounts attributable to noncontrolling interests	73	(75)	(101)
Balance at end of period	930	1,563	905
Other Comprehensive Income (Loss) before Reclassifications, Tax	167	(201)	(256)
Reclassification from AOCI, Current Period, Tax	21	12	1
Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(23)	(6)
Other comprehensive income (loss) before reclassifications, after tax	13	(22)	(11)
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	4	5
Other comprehensive income (loss)	17	(17)	(11)
Amounts attributable to noncontrolling interests
Balance at end of period	(6)	(23)	(6)
Other Comprehensive Income (Loss) before Reclassifications, Tax	(2)	8	5
Reclassification from AOCI, Current Period, Tax	(1)	(2)	0
Pension and Postretirement Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(877)	(855)
Other comprehensive income (loss) before reclassifications, after tax	220	(66)	(102)
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	46	42	34
Other comprehensive income (loss)	266	(24)	(68)
Amounts attributable to noncontrolling interests	(25)	2	6
Balance at end of period	(636)	(877)	(855)
Other Comprehensive Income (Loss) before Reclassifications, Tax	(59)	18	28
Reclassification from AOCI, Current Period, Tax	(12)	(11)	(9)
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(82)	(125)
Other comprehensive income (loss) before reclassifications, after tax	(20)	48	42
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax
Other comprehensive income (loss)	(20)	48	42
Amounts attributable to noncontrolling interests	2	(5)	(4)
Balance at end of period	(100)	(82)	(125)
Other Comprehensive Income (Loss) before Reclassifications, Tax	0	0	0
Reclassification from AOCI, Current Period, Tax	0	0	0
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	581	(68)
Other comprehensive income (loss) before reclassifications, after tax	(419)	680	873
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	(26)	47	38
Other comprehensive income (loss)	(445)	727	911
Amounts attributable to noncontrolling interests	50	(78)	(99)
Balance at end of period	$ 186	581	(68)
Cumulative Effect, Period of Adoption, Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(5)
Balance at end of period			(5)
Cumulative Effect, Period of Adoption, Adjustment | Net Unrealized Gains (Losses) on Investments with OTTI Losses
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			14
Cumulative Effect, Period of Adoption, Adjustment | Net Other Unrealized Gains (Losses) on Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			57
Cumulative Effect, Period of Adoption, Adjustment | Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			5
Cumulative Effect, Period of Adoption, Adjustment | Pension and Postretirement Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(793)
Cumulative Effect, Period of Adoption, Adjustment | Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(163)
Cumulative Effect, Period of Adoption, Adjustment | AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(880)
Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		21,925
Balance at end of period			21,925
Cumulative Effect, Period of Adoption, Adjusted Balance | Net Unrealized Gains (Losses) on Investments with OTTI Losses
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		0
Balance at end of period			0
Cumulative Effect, Period of Adoption, Adjusted Balance | Net Other Unrealized Gains (Losses) on Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		918
Balance at end of period			918
Cumulative Effect, Period of Adoption, Adjusted Balance | Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(6)
Balance at end of period			(6)
Cumulative Effect, Period of Adoption, Adjusted Balance | Pension and Postretirement Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(855)
Balance at end of period			(855)
Cumulative Effect, Period of Adoption, Adjusted Balance | Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(125)
Balance at end of period			(125)
Cumulative Effect, Period of Adoption, Adjusted Balance | AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		$ (68)
Balance at end of period			$ (68)