v3.26.1
Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning balance $ 6,265,408 $ 6,743,872 $ 6,769,871 $ 7,195,661
Reclassifications from accumulated other comprehensive income (loss) to net income        
Reclassification adjustment for gains on cash flow hedges included in net income (2,566) (5,977) (5,961) (11,709)
Other amounts of other comprehensive income (loss)        
Net unrealized gains (losses) on available-for-sale securities 58,671 (54,661) 58,643 (54,541)
Unrealized gains (losses) on cash flow hedges 5,177 (3,293) 9,535 (11,039)
Total other comprehensive income (loss) 61,264 (63,948) 62,208 (77,500)
Ending balance 6,795,514 6,992,551 6,795,514 6,992,551
Accumulated Net Unrealized Investment Gain (Loss) [Member]        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning balance [1] 183,119 125,425 183,147 125,305
Other amounts of other comprehensive income (loss)        
Net unrealized gains (losses) on available-for-sale securities [1] 58,671 (54,661) 58,643 (54,541)
Total other comprehensive income (loss) [1] 58,671 (54,661) 58,643 (54,541)
Ending balance [1] 241,790 70,764 241,790 70,764
Accumulated Defined Benefit Plans Adjustment [Member]        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning balance 805 849 796 1,043
Reclassifications from accumulated other comprehensive income (loss) to net income        
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax (18) (17) (45) (64)
Other amounts of other comprehensive income (loss)        
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment and Tax     36 (147)
Total other comprehensive income (loss) (18) (17) (9) (211)
Ending balance 787 832 787 832
AOCI Attributable to Parent [Member]        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning balance 205,412 165,118 204,468 178,670
Reclassifications from accumulated other comprehensive income (loss) to net income        
Reclassification adjustment for gains on cash flow hedges included in net income (2,566) (5,977) (5,961) (11,709)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax (18) (17) (45) (64)
Other amounts of other comprehensive income (loss)        
Net unrealized gains (losses) on available-for-sale securities 58,671 (54,661) 58,643 (54,541)
Unrealized gains (losses) on cash flow hedges 5,177 (3,293) 9,535 (11,039)
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment and Tax     36 (147)
Total other comprehensive income (loss) 61,264 (63,948) 62,208 (77,500)
Ending balance 266,676 101,170 266,676 101,170
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent        
Accumulated Other Comprehensive Income (Loss) [Roll Forward]        
Beginning balance 21,488 38,844 20,525 52,322
Reclassifications from accumulated other comprehensive income (loss) to net income        
Reclassification adjustment for gains on cash flow hedges included in net income (2,566) (5,977) (5,961) (11,709)
Other amounts of other comprehensive income (loss)        
Unrealized gains (losses) on cash flow hedges 5,177 (3,293) 9,535 (11,039)
Total other comprehensive income (loss) 2,611 (9,270) 3,574 (22,748)
Ending balance $ 24,099 $ 29,574 $ 24,099 $ 29,574
[1]
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(1) Net unrealized gains (losses) on available-for-sale securities are net of unrealized gains and losses relating to hedged interest rate risk included in net income.