Investments - Schedule of Maturities for Fixed Income Securities (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Amortized cost, net
Due in one year or less	$ 1,753	$ 1,544
Due after one year through five years	21,662	22,889
Due after five years through ten years	17,038	17,431
Due after ten years	10,176	10,526
Subtotal	50,629	52,390
ABS	1,711	1,226
Amortized cost, net	52,340	53,616
Fair value
Due in one year or less	1,740	1,531
Due after one year through five years	21,580	22,595
Due after five years through ten years	17,001	17,130
Due after ten years	9,959	10,250
Subtotal	50,280	51,506
ABS	1,713	1,241
Fair value	$ 51,993	$ 52,747