v3.26.3
Marketable Securities - Fair Value of and Gross Unrealized Losses on Investment Securities (Details)
$ in Thousands
 9 Months Ended
Sep. 30, 2026
USD ($)
position
Dec. 31, 2025
USD ($)
Marketable securities available-for-sale    
Less than 12 months - Fair value $ 1,146,694 $ 120,896
Less than 12 months - Unrealized loss (60,637) (283)
12 months or more - Fair value 1,053,084 1,296,824
12 months or more - Unrealized loss (257,891) (211,460)
Total - Fair value 2,199,778 1,417,720
Total - Unrealized loss $ (318,528) (211,743)
Number of investment positions with unrealized losses | position 385  
U.S. government-sponsored enterprises    
Marketable securities available-for-sale    
Less than 12 months - Fair value $ 0 1,055
Less than 12 months - Unrealized loss 0 (13)
12 months or more - Fair value 129,338 150,484
12 months or more - Unrealized loss (17,672) (15,706)
Total - Fair value 129,338 151,539
Total - Unrealized loss (17,672) (15,719)
Municipal securities    
Marketable securities available-for-sale    
Less than 12 months - Fair value 24,626 5,627
Less than 12 months - Unrealized loss (992) (14)
12 months or more - Fair value 35,271 41,333
12 months or more - Unrealized loss (12,319) (7,719)
Total - Fair value 59,897 46,960
Total - Unrealized loss (13,311) (7,733)
Corporate debt issues    
Marketable securities available-for-sale    
Less than 12 months - Fair value 75,579 4,914
Less than 12 months - Unrealized loss (2,276) (86)
12 months or more - Fair value 0 0
12 months or more - Unrealized loss 0 0
Total - Fair value 75,579 4,914
Total - Unrealized loss (2,276) (86)
Mortgage-backed securities    
Marketable securities available-for-sale    
Less than 12 months - Fair value 1,046,489 109,300
Less than 12 months - Unrealized loss (57,369) (170)
12 months or more - Fair value 888,475 1,105,007
12 months or more - Unrealized loss (227,900) (188,035)
Total - Fair value 1,934,964 1,214,307
Total - Unrealized loss $ (285,269) $ (188,205)