Investment Securities (Available For Sale Securities Unrealized Gains And Losses, By Security Type) (Details) - USD ($)	Dec. 31, 2024	Dec. 31, 2023
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 10,127,426,000	$ 10,904,765,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	3,961,000	479,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(994,534,000)	(1,220,484,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	9,136,853,000	9,684,760,000
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	2,594,130,000	841,267,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	2,981,000	81,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(41,859,000)	(24,834,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	2,555,252,000	816,514,000
US Government-sponsored Enterprise Debt Securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	55,425,000	55,658,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	0	0
Available For Sale Securities, Gross Unrealized Loss at Period End	(12,576,000)	(11,696,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	42,849,000	43,962,000
State and municipal obligations [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	822,790,000	1,346,633,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	16,000	24,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(79,915,000)	(149,238,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	742,891,000	1,197,419,000
Agency mortgage-backed securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	4,195,182,000	4,621,821,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	415,000	233,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(750,706,000)	(720,708,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	3,444,891,000	3,901,346,000
Non-agency mortgage-backed securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	625,539,000	1,331,288,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	136,000	136,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(56,986,000)	(173,526,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	568,689,000	1,157,898,000
Asset-backed Securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	1,595,797,000	2,200,712,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	413,000	5,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(39,195,000)	(93,232,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	1,557,015,000	2,107,485,000
Total mortgage and asset-backed securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	6,416,518,000	8,153,821,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	964,000	374,000
Available For Sale Securities, Gross Unrealized Loss at Period End	(846,887,000)	(987,466,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	5,570,595,000	7,166,729,000
Other Debt Securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	238,563,000	507,386,000
Available For Sale Securities, Gross Unreailzed Gain at Period End	0	0
Available For Sale Securities, Gross Unrealized Loss at Period End	(13,297,000)	(47,250,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Fair Value	$ 225,266,000	$ 460,136,000