Significant Accounting Policies - Deferred Acquisition Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred acquisition costs, beginning of the period	$ 1,219	$ 879
Capitalizations	548	564
Amortization expense	(265)	(224)
Deferred acquisition costs, end of the period	$ 1,502	$ 1,219