v3.25.2
Other Comprehensive Income (Loss) (Accumulated Other Comprehensive Income (Loss) by Component) (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance $ 1,896,657 $ 1,907,497 $ 1,862,624 $ 1,927,361
Other comprehensive income (loss) (16,797) 196 (397) (42,598)
Balance 1,888,006 1,915,064 1,888,006 1,915,064
Other Comprehensive Income (Loss), Tax 5,844 5,277 17,316 15,889
Unrealized gain (losses) on securities available for sale        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance (21,291) (32,107) (21,059) (41,173)
Other comprehensive loss before reclassifications, net of tax 2,918 42 2,686 9,108
Amounts reclassified from accumulated other comprehensive income (loss), net of tax 0 0 0 0
Other comprehensive income (loss) 2,918 42 2,686 9,108
Balance (18,373) (32,065) (18,373) (32,065)
Other Comprehensive Income (Loss), Tax 867 12 796 2,703
Defined Benefit Plan        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance (3,435) (8,519) (3,435) (9,147)
Other comprehensive loss before reclassifications, net of tax 0 0 0 418
Amounts reclassified from accumulated other comprehensive income (loss), net of tax 0 105 0 315
Other comprehensive income (loss) 0 105 0 733
Balance (3,435) (8,414) (3,435) (8,414)
Other Comprehensive Income (Loss), Tax 0 31 0 221
Defined Benefit Plan | Reclassification out of Accumulated Other Comprehensive Income        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Other Comprehensive Income (Loss), Tax 0 31 0 95
Total        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance 792 42,418 (15,608) 85,212
Other comprehensive loss before reclassifications, net of tax (8,999) 16,567 27,427 8,863
Amounts reclassified from accumulated other comprehensive income (loss), net of tax (7,798) (16,371) (27,824) (51,461)
Other comprehensive income (loss) (16,797) 196 (397) (42,598)
Balance (16,005) 42,614 (16,005) 42,614
Other Comprehensive Income (Loss), Tax (4,987) 57 (119) (12,648)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance 25,518 83,044 8,886 135,532
Other comprehensive loss before reclassifications, net of tax (11,917) 16,525 24,741 (663)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax (7,798) (16,476) (27,824) (51,776)
Other comprehensive income (loss) (19,715) 49 (3,083) (52,439)
Balance 5,803 83,093 5,803 83,093
Other Comprehensive Income (Loss), Tax (5,854) 14 (915) (15,572)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | Reclassification out of Accumulated Other Comprehensive Income        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Other Comprehensive Income (Loss), Tax $ (2,316) $ (4,893) $ (8,263) $ (15,376)