v3.26.1
Accumulated Other Comprehensive Loss - Changes (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Pre-tax Amount        
Other comprehensive income , Pre-tax Amount $ 17,653 $ 36,496 $ 11,371 $ 77,715
Income Tax Benefit (Expense)        
Other comprehensive loss, Income Tax Benefit (Expense) (4,699) (9,735) (3,024) (20,729)
Net of Tax        
Balance at beginning of year 2,767,760 2,648,852 2,769,365 2,617,486
Other comprehensive income 12,954 26,761 8,347 56,986
Balance at end of period 2,826,028 2,694,545 2,826,028 2,694,545
Accumulated Other Comprehensive Income (Loss)        
Pre-tax Amount        
Accumulated other comprehensive loss, beginning balance, Pre-tax Amount (508,386) (591,574) (502,104) (632,793)
Accumulated other comprehensive loss, ending balance, Pre-tax Amount (490,733) (555,078) (490,733) (555,078)
Income Tax Benefit (Expense)        
Accumulated other comprehensive loss, beginning balance, Income Tax Benefit (Expense) 135,639 157,805 133,964 168,799
Accumulated other comprehensive loss, ending balance, Income Tax Benefit (Expense) 130,940 148,070 130,940 148,070
Net of Tax        
Balance at beginning of year (372,747) (433,769) (368,140) (463,994)
Other comprehensive income 12,954 26,761 8,347 56,986
Balance at end of period (359,793) (407,008) (359,793) (407,008)
Pensions and Other Benefits        
Net of Tax        
Balance at beginning of year (4,290) (1,879) (4,290) (1,879)
Balance at end of period (4,290) (1,879) (4,290) (1,879)
Investment securities        
Pre-tax Amount        
Unrealized net gains (losses) arising during the year, Pre-tax Amount 9,650 26,354 (10,655) 57,717
Reclassification of net losses to net income, Pre-tax Amount   9,982   (37)
Other comprehensive income , Pre-tax Amount 19,354 36,336 12,963 77,319
Income Tax Benefit (Expense)        
Unrealized net gains (losses) arising during the year, Income Tax Benefit (Expense) (2,575) (7,030) 2,842 (15,395)
Reclassification of net losses to net income, Income Tax Benefit (Expense)   (2,663)   10
Other comprehensive loss, Income Tax Benefit (Expense) (5,163) (9,693) (3,458) (20,624)
Net of Tax        
Unrealized net gains (losses) arising during the year, Net of tax 7,075 19,324 (7,813) 42,322
Reclassification of net losses to net income, Net of tax   7,319   (27)
Other comprehensive income 14,191 26,643 9,505 56,695
Amortization of unrealized holding losses on held-to-maturity securities        
Pre-tax Amount        
Reclassification of net losses to net income, Pre-tax Amount 9,704   23,618 19,639
Income Tax Benefit (Expense)        
Reclassification of net losses to net income, Income Tax Benefit (Expense) (2,588)   (6,300) (5,239)
Net of Tax        
Reclassification of net losses to net income, Net of tax 7,116   17,318 14,400
Cash flow derivative hedges        
Pre-tax Amount        
Unrealized net gains (losses) arising during the year, Pre-tax Amount (30) 113 (75) 349
Amounts excluded from the assessment of hedge effectiveness, Pre-tax Amount (1,671) 47 (1,517) 47
Other comprehensive income , Pre-tax Amount (1,701) 160 (1,592) 396
Income Tax Benefit (Expense)        
Unrealized net gains (losses) arising during the year, Income Tax Benefit (Expense) 8 (29) 20 (92)
Amounts excluded from the assessment of hedge effectiveness, Income Tax Benefit (Expense) 456 (13) 414 (13)
Other comprehensive loss, Income Tax Benefit (Expense) 464 (42) 434 (105)
Net of Tax        
Balance at beginning of year (464) 88 (543) (85)
Unrealized net gains (losses) arising during the year, Net of tax (22) 84 (55) 257
Amounts excluded from the assessment of hedge effectiveness, Net of tax (1,215) 34 (1,103) 34
Other comprehensive income (1,237) 118 (1,158) 291
Balance at end of period $ (1,701) $ 206 $ (1,701) $ 206