v3.25.2
Investment Securities (Available-for-sale securities with unrealized losses, fair value) (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]    
Less than 12 Months, Fair Value $ 4,445,870 $ 3,148,559
Less than 12 Months, Unrealized Losses (27,952) (16,054)
12 Months or More, Fair Value 6,715,840 6,470,569
12 Months or More, Unrealized Losses (179,149) (155,518)
TOTAL, Fair Value 11,161,710 9,619,128
TOTAL, Unrealized Losses (207,101) (171,572)
U.S. Treasury obligations [Member]    
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]    
Less than 12 Months, Fair Value 715,040 244,268
Less than 12 Months, Unrealized Losses (474) (1,144)
12 Months or More, Fair Value 2,586,872 2,754,861
12 Months or More, Unrealized Losses (94,601) (74,652)
TOTAL, Fair Value 3,301,912 2,999,129
TOTAL, Unrealized Losses (95,075) (75,796)
State or local housing agency obligations [Member]    
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]    
Less than 12 Months, Fair Value 24,337 24,179
Less than 12 Months, Unrealized Losses (13) (286)
12 Months or More, Fair Value 0 0
12 Months or More, Unrealized Losses 0 0
TOTAL, Fair Value 24,337 24,179
TOTAL, Unrealized Losses (13) (286)
Non-mortgage-backed securities [Member]    
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]    
Less than 12 Months, Fair Value 739,377 268,447
Less than 12 Months, Unrealized Losses (487) (1,430)
12 Months or More, Fair Value 2,586,872 2,754,861
12 Months or More, Unrealized Losses (94,601) (74,652)
TOTAL, Fair Value 3,326,249 3,023,308
TOTAL, Unrealized Losses (95,088) (76,082)
U.S. obligation MBS [Member]    
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]    
Less than 12 Months, Fair Value 0 0
Less than 12 Months, Unrealized Losses 0 0
12 Months or More, Fair Value 67,487 77,263
12 Months or More, Unrealized Losses (1,022) (783)
TOTAL, Fair Value 67,487 77,263
TOTAL, Unrealized Losses (1,022) (783)
GSE MBS [Member]    
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]    
Less than 12 Months, Fair Value 3,706,493 2,880,112
Less than 12 Months, Unrealized Losses (27,465) (14,624)
12 Months or More, Fair Value 4,061,481 3,638,445
12 Months or More, Unrealized Losses (83,526) (80,083)
TOTAL, Fair Value 7,767,974 6,518,557
TOTAL, Unrealized Losses (110,991) (94,707)
Mortgage-backed securities [Member]    
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]    
Less than 12 Months, Fair Value 3,706,493 2,880,112
Less than 12 Months, Unrealized Losses (27,465) (14,624)
12 Months or More, Fair Value 4,128,968 3,715,708
12 Months or More, Unrealized Losses (84,548) (80,866)
TOTAL, Fair Value 7,835,461 6,595,820
TOTAL, Unrealized Losses $ (112,013) $ (95,490)