Significant Accounting Policies - Deferred Acquisition Costs (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred acquisition costs, beginning of the period	$ 1,219	$ 879
Capitalizations	414	423
Amortization expense	(196)	(163)
Deferred acquisition costs, end of the period	$ 1,437	$ 1,139