v3.25.2
Other Comprehensive Income - Schedule of Accumulated Other Comprehensive Income, Net of Tax (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning Balance     $ (1,252,004)  
Other comprehensive income (loss), net of tax $ (11,261) $ (33,061) 111,532 $ (190,125)
Ending Balance (1,140,472)   (1,140,472)  
Securities Available For Sale [Member]        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning Balance     (1,230,828) (1,094,794)
Other comprehensive income (loss) before reclassifications     111,032 (190,786)
Reclassification of amounts included in net income     11 0
Other comprehensive income (loss), net of tax     111,043 (190,786)
Ending Balance (1,119,785) (1,285,580) (1,119,785) (1,285,580)
Defined Benefit Plans [Member]        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning Balance     (21,176) (24,425)
Other comprehensive income (loss) before reclassifications     0 0
Reclassification of amounts included in net income     489 661
Other comprehensive income (loss), net of tax     489 661
Ending Balance (20,687) (23,764) (20,687) (23,764)
AOCI Attributable to Parent [Member]        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning Balance     (1,252,004) (1,119,219)
Other comprehensive income (loss) before reclassifications     111,032 (190,786)
Reclassification of amounts included in net income     500 661
Other comprehensive income (loss), net of tax     111,532 (190,125)
Ending Balance $ (1,140,472) $ (1,309,344) $ (1,140,472) $ (1,309,344)