Fair Value Measurements (Summary Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands		Sep. 30, 2024	Dec. 31, 2023
Fair Value Measurements [Line Items]
Residential mortgage loans held for sale		$ 1,605	$ 1,585
U.S. government and federal agency obligations		2,406,840	816,514
Government-sponsored enterprise obligations		45,499	43,962
State and municipal obligations		782,382	1,197,419
Agency mortgage-backed securities		3,673,971	3,901,346
Non-agency mortgage-backed securities		609,344	1,157,898
Asset-backed securities		1,444,597	2,107,485
Other debt securities		205,048	460,136
Trading debt securities		42,645	28,830
Equity securities		48,262	5,723
Private equity investments		170,973	176,667
Derivative Asset	[1]	99,862	116,876
Assets held in trust for deferred compensation plan		21,989	20,538
Total assets		9,553,017	10,034,979
Derivative Liabilities	[1]	26,896	37,899
Liabilities held in trust for deferred compensation plan		21,989	20,538
Total Liabilities		48,885	58,437
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Measurements [Line Items]
Residential mortgage loans held for sale		0	0
U.S. government and federal agency obligations		2,406,840	816,514
Government-sponsored enterprise obligations		0	0
State and municipal obligations		0	0
Agency mortgage-backed securities		0	0
Non-agency mortgage-backed securities		0	0
Asset-backed securities		0	0
Other debt securities		0	0
Trading debt securities		0	0
Equity securities		48,262	5,723
Private equity investments		0	0
Derivative Asset	[1]	0	0
Assets held in trust for deferred compensation plan		21,989	20,538
Total assets		2,477,091	842,775
Derivative Liabilities	[1]	0	0
Liabilities held in trust for deferred compensation plan		21,989	20,538
Total Liabilities		21,989	20,538
Significant Other Observable Inputs (Level 2)
Fair Value Measurements [Line Items]
Residential mortgage loans held for sale		1,605	1,585
U.S. government and federal agency obligations		0	0
Government-sponsored enterprise obligations		45,499	43,962
State and municipal obligations		781,431	1,196,472
Agency mortgage-backed securities		3,673,971	3,901,346
Non-agency mortgage-backed securities		609,344	1,157,898
Asset-backed securities		1,444,597	2,107,485
Other debt securities		205,048	460,136
Trading debt securities		42,645	28,830
Equity securities		0	0
Private equity investments		0	0
Derivative Asset	[1]	99,565	116,710
Assets held in trust for deferred compensation plan		0	0
Total assets		6,903,705	9,014,424
Derivative Liabilities	[1]	26,755	37,704
Liabilities held in trust for deferred compensation plan		0	0
Total Liabilities		26,755	37,704
Significant Unobservable Inputs (Level 3)
Fair Value Measurements [Line Items]
Residential mortgage loans held for sale		0	0
U.S. government and federal agency obligations		0	0
Government-sponsored enterprise obligations		0	0
State and municipal obligations		951	947
Agency mortgage-backed securities		0	0
Non-agency mortgage-backed securities		0	0
Asset-backed securities		0	0
Other debt securities		0	0
Trading debt securities		0	0
Equity securities		0	0
Private equity investments		170,973	176,667
Derivative Asset	[1]	297	166
Assets held in trust for deferred compensation plan		0	0
Total assets		172,221	177,780
Derivative Liabilities	[1]	141	195
Liabilities held in trust for deferred compensation plan		0	0
Total Liabilities		$ 141	$ 195

[1] * The fair value of each class of derivative is shown in Note 11.