v3.26.1
Shareholders' Equity Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Balance, beginning of period $ 5,920,680 $ 5,550,957
Net change in unrealized gain (loss) (84,412) 173,828
Interest revenue, Investment securities 7,376 9,444
Other comprehensive income, before income taxes (77,036) 183,272
Federal and state income taxes (18,204) 42,575
Other comprehensive income, net of income taxes (58,832) 140,697
Balance, end of period 5,975,066 5,774,378
Accumulated Net Unrealized Gain (Loss) on Available for Sale Securities [Member]    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Balance, beginning of period (102,569) (412,348)
Net change in unrealized gain (loss) (84,412) 173,828
Interest revenue, Investment securities 0 0
Other comprehensive income, before income taxes (84,412) 173,828
Federal and state income taxes (19,947) 40,476
Other comprehensive income, net of income taxes (64,465) 133,352
Balance, end of period (167,034) (278,996)
AOCI, Accumulated Gain (Loss), Debt Securities, Investment Securities Transferred from Available-for-sale, Parent    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Balance, beginning of period (63,601) (90,692)
Net change in unrealized gain (loss) 0 0
Interest revenue, Investment securities 7,376 9,444
Other comprehensive income, before income taxes 7,376 9,444
Federal and state income taxes 1,743 2,099
Other comprehensive income, net of income taxes 5,633 7,345
Balance, end of period (57,968) (83,347)
Accumulated Other Comprehensive Income (Loss) [Member]    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Balance, beginning of period (166,170) (503,040)
Net change in unrealized gain (loss) (84,412) 173,828
Interest revenue, Investment securities 7,376 9,444
Other comprehensive income, before income taxes (77,036) 183,272
Federal and state income taxes (18,204) 42,575
Other comprehensive income, net of income taxes (58,832) 140,697
Balance, end of period $ (225,002) $ (362,343)