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, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	$ (175)	$ (209)	$ (160)	$ (253)
Other comprehensive income before reclassifications	(94)	52	(89)	13
Amounts reclassified from accumulated other comprehensive income	0	(1)	(10)	4
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	94	(53)	79	(9)
Ending Balance	(81)	(262)	(81)	(262)
Income Tax Expense (Benefit)	3	1	10	7
Realized Investment Gains (Losses)	(1)	1	3	(7)
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(23)	(67)	(20)	(71)
Other comprehensive income before reclassifications	(37)	23	(38)	24
Amounts reclassified from accumulated other comprehensive income	0	0	(5)	6
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	37	(23)	34	(19)
Ending Balance	13	(90)	13	(90)
Realized Investment Gains (Losses)	1	(1)	(3)	7
Accumulated Translation Adjustment [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(151)	(147)	(144)	(184)
Other comprehensive income before reclassifications	(57)	29	(51)	(8)
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	57	(29)	51	8
Ending Balance	(93)	(176)	(93)	(176)
Accumulated Gain (Loss), Financial Liability, Fair Value Option, Attributable to Parent [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(1)	(1)	(1)	(1)
Other comprehensive income before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	0	0	0	0
Ending Balance	(1)	(1)	(1)	(1)
Other Postretirement Benefits Plan [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	0	6	5	3
Other comprehensive income before reclassifications	0	0	0	(3)
Amounts reclassified from accumulated other comprehensive income	0	0	(5)	(1)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	0	0	(5)	2
Ending Balance	0	5	0	5
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)	(2)	0	(2)	(1)
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	0	(1)
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income	0	0	(5)	(1)
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	(5)	(1)
Income Tax Expense (Benefit)	$ 0	$ 0	$ 0	$ 0