v3.26.1
Stockholders' Equity (Components of 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) [Line Items]        
Balance $ 4,419,592 $ 4,278,672 $ 4,460,117 $ 4,127,636
Reclassification of net loss realized and included in earnings 5,917 9,668 110,509 19,083
Amortization of unrealized net loss on securities transferred to HTM 400 387 813 792
Income tax (expense) benefit 6,038 (13,181) (8,873) (41,393)
Balance 4,444,134 4,365,419 4,444,134 4,365,419
Accumulated Other Comprehensive Loss Available for Sale Securities [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance     (293,835) (473,679)
Net change in unrealized gain (loss)     (53,914) 146,860
Reclassification of net loss realized and included in earnings     98,595  
Income tax (expense) benefit     (10,082) (34,140)
Balance (259,236) (360,959) (259,236) (360,959)
Held to Maturity Securities Transferred from AFS [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance     (6,858) (8,071)
Amortization of unrealized net loss on securities transferred to HTM     813 792
Income tax (expense) benefit     (184) (196)
Balance (6,229) (7,475) (6,229) (7,475)
Employee Benefit Plans [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance     (61,448) (77,235)
Reclassification of net loss realized and included in earnings     270 1,888
Valuation adjustments to employee benefit plans     (496)  
Income tax (expense) benefit     51 (594)
Balance (61,623) (75,941) (61,623) (75,941)
Accumulated Other Comprehensive Loss [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance (325,127) (514,972) (376,251) (606,092)
Net change in unrealized gain (loss)     (71,123) 157,783
Reclassification of net loss realized and included in earnings     110,509 19,083
Valuation adjustments to employee benefit plans     (496)  
Amortization of unrealized net loss on securities transferred to HTM     813 792
Income tax (expense) benefit     (8,873) (41,393)
Balance (345,421) (469,827) (345,421) (469,827)
Gains and Losses on Cash Flow Hedges [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance     (14,795) (47,136)
Net change in unrealized gain (loss)     (17,595) 11,096
Reclassification of net loss realized and included in earnings     11,644 17,195
Income tax (expense) benefit     1,342 (6,463)
Balance (19,404) (25,308) (19,404) (25,308)
Equity Method Investment [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance     685 29
Net change in unrealized gain (loss)     386 (173)
Balance $ 1,071 $ (144) $ 1,071 $ (144)