Fair Value Measurements (Summary Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands		Jun. 30, 2023	Dec. 31, 2022
Fair Value Measurements [Line Items]
Residential mortgage loans held for sale		$ 1,566	$ 0
U.S. government and federal agency obligations		945,815	1,035,406
Government-sponsored enterprise obligations		44,036	43,108
State and municipal obligations		1,227,737	1,767,109
Agency mortgage-backed securities		4,065,406	4,308,427
Non-agency mortgage-backed securities		1,174,790	1,211,607
Asset-backed securities		2,499,675	3,397,801
Other debt securities		457,166	474,858
Trading debt securities		29,412	43,523
Equity securities		5,520	6,210
Private equity investments		172,732	178,127
Derivative Asset	[1]	104,936	60,492
Assets held in trust for deferred compensation plan		19,482	17,856
Total assets		10,748,273	12,544,524
Derivative Liabilities	[1]	51,998	54,984
Liabilities held in trust for deferred compensation plan		19,482	17,856
Total Liabilities		71,480	72,840
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		945,815	1,035,406
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		5,520	6,210
Private equity investments		0	0
Derivative Asset	[1]	0	0
Assets held in trust for deferred compensation plan		19,482	17,856
Total assets		970,817	1,059,472
Derivative Liabilities	[1]	0	0
Liabilities held in trust for deferred compensation plan		19,482	17,856
Total Liabilities		19,482	17,856
Significant Other Observable Inputs (Level 2)
Fair Value Measurements [Line Items]
Residential mortgage loans held for sale		1,566	0
U.S. government and federal agency obligations		0	0
Government-sponsored enterprise obligations		44,036	43,108
State and municipal obligations		1,226,817	1,765,268
Agency mortgage-backed securities		4,065,406	4,308,427
Non-agency mortgage-backed securities		1,174,790	1,211,607
Asset-backed securities		2,499,675	3,397,801
Other debt securities		457,166	474,858
Trading debt securities		29,412	43,523
Equity securities		0	0
Private equity investments		0	0
Derivative Asset	[1]	104,843	60,458
Assets held in trust for deferred compensation plan		0	0
Total assets		9,603,711	11,305,050
Derivative Liabilities	[1]	51,910	54,865
Liabilities held in trust for deferred compensation plan		0	0
Total Liabilities		51,910	54,865
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		920	1,841
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		172,732	178,127
Derivative Asset	[1]	93	34
Assets held in trust for deferred compensation plan		0	0
Total assets		173,745	180,002
Derivative Liabilities	[1]	88	119
Liabilities held in trust for deferred compensation plan		0	0
Total Liabilities		$ 88	$ 119

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