Investment Securities (Summary Of Available For Sale Investment Securities By Maturity Groupings) (Details) - USD ($)		Dec. 31, 2023	Dec. 31, 2022
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost		$ 10,904,765,000	$ 13,738,206,000
Debt Securities, Available-for-sale, Fair Value		9,684,760,000	12,238,316,000
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost		841,267,000	1,078,807,000
Debt Securities, Available-for-sale, Fair Value		816,514,000	1,035,406,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Amortized Cost		399,926,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value		394,466,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost		263,138,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value		255,368,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Amortized Cost		178,203,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Fair Value		$ 166,680,000
Debt Securities, Available-for-Sale, Weighted Average Yield	[1]	1.19%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, Year One	[1]	1.44%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, after Year One Through Five	[1]	1.26%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, after Year 5 Through 10	[1]	0.54%
US Government-sponsored Enterprise Debt Securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost		$ 55,658,000	55,729,000
Debt Securities, Available-for-sale, Fair Value		43,962,000	43,108,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Amortized Cost		4,948,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Fair Value		4,505,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Amortized Cost		50,710,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value		$ 39,457,000
Debt Securities, Available-for-Sale, Weighted Average Yield		2.38%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, after Year 5 Through 10		2.94%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, after Year 10		2.32%
State and municipal obligations [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost		$ 1,346,633,000	1,965,028,000
Debt Securities, Available-for-sale, Fair Value		1,197,419,000	1,767,109,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Amortized Cost		62,701,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value		61,763,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost		403,542,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value		376,194,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Amortized Cost		750,535,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Fair Value		649,221,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Amortized Cost		129,855,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value		$ 110,241,000
Debt Securities, Available-for-Sale, Weighted Average Yield		1.78%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, Year One		1.31%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, after Year One Through Five		1.67%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, after Year 5 Through 10		1.82%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, after Year 10		2.13%
Agency mortgage-backed securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost		$ 4,621,821,000	5,087,893,000
Debt Securities, Available-for-sale, Fair Value		$ 3,901,346,000	4,308,427,000
Debt Securities, Available-for-Sale, Weighted Average Yield		2.10%
Non-agency mortgage-backed securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost		$ 1,331,288,000	1,423,469,000
Debt Securities, Available-for-sale, Fair Value		$ 1,157,898,000	1,211,607,000
Debt Securities, Available-for-Sale, Weighted Average Yield		2.37%
Asset-backed Securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost		$ 2,200,712,000	3,588,025,000
Debt Securities, Available-for-sale, Fair Value		$ 2,107,485,000	3,397,801,000
Debt Securities, Available-for-Sale, Weighted Average Yield		2.33%
Total mortgage and asset-backed securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost		$ 8,153,821,000	10,099,387,000
Debt Securities, Available-for-sale, Fair Value		$ 7,166,729,000	8,917,835,000
Debt Securities, Available-for-Sale, Weighted Average Yield		2.20%
Other Debt Securities [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Amortized Cost		$ 507,386,000	539,255,000
Debt Securities, Available-for-sale, Fair Value		460,136,000	$ 474,858,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Amortized Cost		48,102,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value		47,374,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost		206,942,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value		195,385,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Amortized Cost		239,082,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 5 through 10 Years, Fair Value		205,950,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Amortized Cost		13,260,000
Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value		$ 11,427,000
Debt Securities, Available-for-Sale, Weighted Average Yield		1.91%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, Year One		1.87%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, after Year One Through Five		2.02%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, after Year 5 Through 10		1.83%
Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, after Year 10		1.82%

[1] Rate does not reflect inflation adjustment on inflation-protected securities