Shareholders' Equity - Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 19,175	$ 19,181
Other comprehensive income (loss) before reclassifications, after tax	(3,997)	(419)	$ 680
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	139	(26)	47
Other comprehensive income (loss)	(3,858)	(445)	727
Amounts attributable to noncontrolling interests	388	50	(78)
Balance at end of period	15,478	19,175	19,181
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
Net Unrealized Gains (Losses) on Investments with an Allowance for Credit Losses
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(2)	0
Other comprehensive income (loss) before reclassifications, after tax		(7)	(43)
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	(5)	5	43
Other comprehensive income (loss)	(5)	(2)	0
Amounts attributable to noncontrolling interests
Balance at end of period	(7)	(2)	0
Other comprehensive income (loss) before reclassifications, tax	0	2	12
Reclassification from AOCI, current period, tax	1	(1)	(12)
Net Unrealized Gains (Losses) on Investments with an Allowance for Credit Losses | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			0
Net Unrealized Gains (Losses) on Other Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	930	1,563
Other comprehensive income (loss) before reclassifications, after tax	(3,903)	(625)	763
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	126	(81)	(43)
Other comprehensive income (loss)	(3,777)	(706)	720
Amounts attributable to noncontrolling interests	378	73	(75)
Balance at end of period	(2,469)	930	1,563
Other comprehensive income (loss) before reclassifications, tax	1,028	167	(201)
Reclassification from AOCI, current period, tax	(21)	21	12
Net Unrealized Gains (Losses) on Other Investments | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			918
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)	(23)
Other comprehensive income (loss) before reclassifications, after tax	20	13	(22)
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax		4	5
Other comprehensive income (loss)	20	17	(17)
Amounts attributable to noncontrolling interests
Balance at end of period	14	(6)	(23)
Other comprehensive income (loss) before reclassifications, tax	(7)	(2)	8
Reclassification from AOCI, current period, tax	0	(1)	(2)
Unrealized Gains (Losses) on Cash Flow Hedges | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(6)
Pension and Postretirement Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(636)	(877)
Other comprehensive income (loss) before reclassifications, after tax	(3)	220	(66)
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	18	46	42
Other comprehensive income (loss)	15	266	(24)
Amounts attributable to noncontrolling interests	(1)	(25)	2
Balance at end of period	(622)	(636)	(877)
Other comprehensive income (loss) before reclassifications, tax	1	(59)	18
Reclassification from AOCI, current period, tax	(5)	(12)	(11)
Pension and Postretirement Benefits | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(855)
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(100)	(82)
Other comprehensive income (loss) before reclassifications, after tax	(111)	(20)	48
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax
Other comprehensive income (loss)	(111)	(20)	48
Amounts attributable to noncontrolling interests	11	2	(5)
Balance at end of period	(200)	(100)	(82)
Other comprehensive income (loss) before reclassifications, tax	0	0	0
Reclassification from AOCI, current period, tax	0	0	0
Foreign Currency Translation | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(125)
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	186	581
Balance at end of period	$ (3,284)	$ 186	581
AOCI Including Portion Attributable to Noncontrolling Interest | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			$ (68)