Fair Value Measurements (Summary Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands		Mar. 31, 2025	Dec. 31, 2024
Fair Value Measurements [Line Items]
Residential mortgage loans held for sale		$ 2,702	$ 2,981
U.S. government and federal agency obligations		2,626,635	2,555,252
Government-sponsored enterprise obligations		44,056	42,849
State and municipal obligations		721,187	742,891
Agency mortgage-backed securities		3,430,566	3,444,891
Non-agency mortgage-backed securities		566,126	568,689
Asset-backed securities		1,625,282	1,557,015
Other debt securities		251,095	225,266
Trading debt securities		56,569	38,034
Equity securities		48,951	48,359
Private equity investments		175,618	184,386
Derivative Asset	[1]	69,339	62,648
Assets held in trust for deferred compensation plan		20,873	21,849
Total assets		9,638,999	9,495,110
Derivative Liabilities	[1]	23,312	26,963
Liabilities held in trust for deferred compensation plan		20,873	21,849
Total Liabilities		44,185	48,812
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		2,626,635	2,555,252
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		10,325	10,219
Equity securities		48,951	48,359
Private equity investments		0	0
Derivative Asset	[1]	0	0
Assets held in trust for deferred compensation plan		20,873	21,849
Total assets		2,706,784	2,635,679
Derivative Liabilities	[1]	0	0
Liabilities held in trust for deferred compensation plan		20,873	21,849
Total Liabilities		20,873	21,849
Significant Other Observable Inputs (Level 2)
Fair Value Measurements [Line Items]
Residential mortgage loans held for sale		2,702	2,981
U.S. government and federal agency obligations		0	0
Government-sponsored enterprise obligations		44,056	42,849
State and municipal obligations		720,240	741,927
Agency mortgage-backed securities		3,430,566	3,444,891
Non-agency mortgage-backed securities		566,126	568,689
Asset-backed securities		1,625,282	1,557,015
Other debt securities		251,095	225,266
Trading debt securities		46,244	27,815
Equity securities		0	0
Private equity investments		0	0
Derivative Asset	[1]	69,189	62,555
Assets held in trust for deferred compensation plan		0	0
Total assets		6,755,500	6,673,988
Derivative Liabilities	[1]	23,233	26,905
Liabilities held in trust for deferred compensation plan		0	0
Total Liabilities		23,233	26,905
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		947	964
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		175,618	184,386
Derivative Asset	[1]	150	93
Assets held in trust for deferred compensation plan		0	0
Total assets		176,715	185,443
Derivative Liabilities	[1]	79	58
Liabilities held in trust for deferred compensation plan		0	0
Total Liabilities		$ 79	$ 58

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