Significant Accounting Policies - Deferred Acquisition Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred acquisition costs, beginning of the period	$ 1,747	$ 1,502
Capitalization	133	134
Amortization expense	(86)	(76)
Deferred acquisition costs, end of the period	$ 1,794	$ 1,560