v3.22.4
Other Comprehensive Income (Loss) (Accumulated Other Comprehensive Income (Loss) by Component) (Details) - USD ($)
$ in Thousands
 3 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]    
Balance $ 1,844,339 $ 1,732,280
Other comprehensive income (loss) (128) 17,662
Balance 1,849,589 1,753,370
Reclassification out of Accumulated Other Comprehensive Income    
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]    
Reclassification from AOCI, Current Period, Tax (1,427) 2,450
Unrealized gain (losses) on securities available for sale    
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]    
Balance (33,899) 961
Other comprehensive loss before reclassifications, net of tax (1,961) (3,083)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax 0 0
Other comprehensive income (loss) (1,961) (3,083)
Balance (35,860) (2,122)
Cash Flow Hedges    
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]    
Balance 68,883 (58,210)
Other comprehensive loss before reclassifications, net of tax 6,775 12,270
Amounts reclassified from accumulated other comprehensive income (loss), net of tax (5,139) 8,379
Other comprehensive income (loss) 1,636 20,649
Balance 70,519 (37,561)
Defined Benefit Plan    
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]    
Balance (11,835) (10,552)
Other comprehensive loss before reclassifications, net of tax 0 0
Amounts reclassified from accumulated other comprehensive income (loss), net of tax 197 96
Other comprehensive income (loss) 197 96
Balance (11,638) (10,456)
Total    
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]    
Balance 23,149 (67,801)
Other comprehensive loss before reclassifications, net of tax 4,814 9,187
Amounts reclassified from accumulated other comprehensive income (loss), net of tax (4,942) 8,475
Other comprehensive income (loss) (128) 17,662
Balance 23,021 (50,139)
Other Comprehensive Income (Loss) before Reclassifications, Tax $ 1,574 $ 2,730