Comprehensive Income - Schedule of Changes in Balances of Each Component of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	$ (160)	$ (253)
Other comprehensive income before reclassifications	14	(33)
Amounts reclassified from accumulated other comprehensive income	(1)	3
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(15)	36
Ending Balance	(175)	(217)
Income Tax Expense (Benefit)	5	4
Realized Investment Gains (Losses)	1	(4)
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(20)	(71)
Other comprehensive income before reclassifications	6	(14)
Amounts reclassified from accumulated other comprehensive income	(1)	4
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(7)	17
Ending Balance	(27)	(54)
Realized Investment Gains (Losses)	(1)	4
Accumulated Translation Adjustment [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(144)	(184)
Other comprehensive income before reclassifications	8	(16)
Amounts reclassified from accumulated other comprehensive income	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(8)	16
Ending Balance	(152)	(168)
Accumulated Gain (Loss), Financial Liability, Fair Value Option, Attributable to Parent [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(1)	(1)
Other comprehensive income before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	0	0
Ending Balance	(1)	(1)
Other Postretirement Benefits Plan [Member]
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	5	3
Other comprehensive income before reclassifications	0	(3)
Amounts reclassified from accumulated other comprehensive income	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	0	3
Ending Balance	5	6
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	(1)
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
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income	0	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	0	0
Income Tax Expense (Benefit)	$ 0	$ 0