v3.26.1
Investment Securities (Available For Sale Securities Unrealized Gains And Losses, By Security Type) (Details) - USD ($)
Jun. 30, 2026
Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost $ 8,941,232,000 $ 9,742,278,000
Gross Unrealized Gains 10,916,000 45,329,000
Gross Unrealized Losses (629,514,000) (692,094,000)
Allowance for Credit Losses 0 0
Fair Value 8,322,634,000 9,095,513,000
U.S. government and federal agency obligations    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 3,503,671,000 3,257,561,000
Gross Unrealized Gains 5,968,000 32,403,000
Gross Unrealized Losses (22,830,000) (10,864,000)
Allowance for Credit Losses 0 0
Fair Value 3,486,809,000 3,279,100,000
Government-sponsored enterprise obligations    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 54,591,000 54,951,000
Gross Unrealized Gains 0 0
Gross Unrealized Losses (10,742,000) (10,239,000)
Allowance for Credit Losses 0 0
Fair Value 43,849,000 44,712,000
State and municipal obligations [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 689,966,000 715,037,000
Gross Unrealized Gains 41,000 37,000
Gross Unrealized Losses (49,783,000) (50,341,000)
Allowance for Credit Losses 0 0
Fair Value 640,224,000 664,733,000
Agency mortgage-backed securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 3,095,101,000 3,786,811,000
Gross Unrealized Gains 1,529,000 1,380,000
Gross Unrealized Losses (494,340,000) (565,086,000)
Allowance for Credit Losses 0 0
Fair Value 2,602,290,000 3,223,105,000
Non-Agency Mortgage-Backed Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 416,247,000 467,200,000
Gross Unrealized Gains 192,000 430,000
Gross Unrealized Losses (31,121,000) (31,942,000)
Allowance for Credit Losses 0 0
Fair Value 385,318,000 435,688,000
Asset-backed securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 1,013,942,000 1,269,503,000
Gross Unrealized Gains 2,988,000 9,503,000
Gross Unrealized Losses (14,272,000) (16,961,000)
Allowance for Credit Losses 0 0
Fair Value 1,002,658,000 1,262,045,000
Total Mortgage And Asset-Backed Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 4,525,290,000 5,523,514,000
Gross Unrealized Gains 4,709,000 11,313,000
Gross Unrealized Losses (539,733,000) (613,989,000)
Allowance for Credit Losses 0 0
Fair Value 3,990,266,000 4,920,838,000
Other debt securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 167,714,000 191,215,000
Gross Unrealized Gains 198,000 1,576,000
Gross Unrealized Losses (6,426,000) (6,661,000)
Allowance for Credit Losses 0 0
Fair Value $ 161,486,000 $ 186,130,000