Debt Securities Available for Sale - AFS debt securities in a continuous unrealized loss position (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	$ 9,327,030	$ 2,385,549
Less than 12 months Gross Unrealized Losses	14,760	27,848
12 months or more Fair Value	8,003,062	8,771,666
12 months or more Gross Unrealized Losses	1,098,437	1,246,136
Total Fair Value	17,330,092	11,157,215
Total Gross Unrealized Losses	1,113,197	1,273,984
US Treasury Securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	9,272,746	2,309,894
Less than 12 months Gross Unrealized Losses	12,743	24,646
12 months or more Fair Value	2,908,217	3,638,092
12 months or more Gross Unrealized Losses	57,545	85,010
Total Fair Value	12,180,963	5,947,986
Total Gross Unrealized Losses	70,288	109,656
Collateralized Mortgage Obligations - Federal agencies
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	4,630	4,878
Less than 12 months Gross Unrealized Losses	2	27
12 months or more Fair Value	97,990	102,160
12 months or more Gross Unrealized Losses	8,645	9,861
Total Fair Value	102,620	107,038
Total Gross Unrealized Losses	8,647	9,888
Mortgage Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	49,654	70,777
Less than 12 months Gross Unrealized Losses	2,015	3,175
12 months or more Fair Value	4,996,855	5,031,414
12 months or more Gross Unrealized Losses	1,032,247	1,151,265
Total Fair Value	5,046,509	5,102,191
Total Gross Unrealized Losses	$ 1,034,262	$ 1,154,440