Investments - Schedule of Maturities for Fixed Income Securities (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Amortized cost, net
Due in one year or less	$ 1,949	$ 1,464
Due after one year through five years	20,816	22,582
Due after five years through ten years	19,120	21,538
Due after ten years	13,765	9,712
Subtotal	55,650	55,296
ABS and MBS	3,688	3,434
Amortized cost, net	59,338	58,730
Fair value
Due in one year or less	1,944	1,460
Due after one year through five years	20,756	22,706
Due after five years through ten years	19,091	21,780
Due after ten years	13,575	9,691
Subtotal	55,366	55,637
ABS and MBS	3,694	3,478
Fair value	$ 59,060	$ 59,115