Investment Securities (Available For Sale Securities Unrealized Gains And Losses, By Security Type) (Details) - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 9,742,278,000	$ 10,127,426,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	45,329,000	3,961,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(692,094,000)	(994,534,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	9,095,513,000	9,136,853,000
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	3,257,561,000	2,594,130,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	32,403,000	2,981,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(10,864,000)	(41,859,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	3,279,100,000	2,555,252,000
US Government-sponsored Enterprise Debt Securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	54,951,000	55,425,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	0	0
Available For Sale Securities, Gross Unrealized Loss at Period End	(10,239,000)	(12,576,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	44,712,000	42,849,000
State and municipal obligations [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	715,037,000	822,790,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	37,000	16,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(50,341,000)	(79,915,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	664,733,000	742,891,000
Agency mortgage-backed securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	3,786,811,000	4,195,182,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	1,380,000	415,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(565,086,000)	(750,706,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	3,223,105,000	3,444,891,000
Non-agency mortgage-backed securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	467,200,000	625,539,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	430,000	136,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(31,942,000)	(56,986,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	435,688,000	568,689,000
Asset-backed Securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	1,269,503,000	1,595,797,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	9,503,000	413,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(16,961,000)	(39,195,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	1,262,045,000	1,557,015,000
Total mortgage and asset-backed securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	5,523,514,000	6,416,518,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	11,313,000	964,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(613,989,000)	(846,887,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	4,920,838,000	5,570,595,000
Other Debt Securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	191,215,000	238,563,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	1,576,000	0
Available For Sale Securities, Gross Unrealized Loss at Period End	(6,661,000)	(13,297,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	$ 186,130,000	$ 225,266,000