Comprehensive Income - Schedule of Changes in Balances of Each Component of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	$ (209)	$ (196)	$ (253)	$ 58
Other comprehensive income before reclassifications	52	111	13	360
Amounts reclassified from accumulated other comprehensive income	(1)	(7)	4	(12)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(53)	(118)	(9)	(372)
Ending Balance	(262)	(315)	(262)	(315)
Income Tax Expense (Benefit)	1	2	7	4
Realized Investment Gains (Losses)	1	14	(7)	31
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(67)	(23)	(71)	154
Other comprehensive income before reclassifications	23	53	24	224
Amounts reclassified from accumulated other comprehensive income	0	(6)	6	(12)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(23)	(59)	(19)	(236)
Ending Balance	(90)	(82)	(90)	(82)
Realized Investment Gains (Losses)	(1)	(8)
Accumulated Translation Adjustment [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(147)	(177)	(184)	(100)
Other comprehensive income before reclassifications	29	58	(8)	136
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(29)	(58)	8	(136)
Ending Balance	(176)	(235)	(176)	(235)
Accumulated Gain (Loss), Financial Liability, Fair Value Option, Attributable to Parent [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(1)	0	(1)	(1)
Other comprehensive income before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income	0	(1)	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	0	(1)	0	0
Ending Balance	(1)	(1)	(1)	(1)
Other Postretirement Benefits Plan [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	6	4	3	4
Other comprehensive income before reclassifications	0	0	(3)	0
Amounts reclassified from accumulated other comprehensive income	0	0	(1)	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	0	0	2	(1)
Ending Balance	5	4	5	4
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Income Tax Expense (Benefit)	0	2	(1)	5
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Gain (Loss), Financial Liability, Fair Value Option, Attributable to Parent [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Income Tax Expense (Benefit)			0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Other Postretirement Benefits Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	0	0	(1)	0
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income	0	0	(1)	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	0	0	(1)	0
Income Tax Expense (Benefit)	$ 0	$ 0	$ 0	$ 0