Fair Value Measurements (Summary Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands		Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure		$ 1,585	$ 0
U.S. government and federal agency obligations		816,514	1,035,406
Government-sponsored enterprise obligations		43,962	43,108
State and municipal obligations		1,197,419	1,767,109
Agency mortgage-backed securities		3,901,346	4,308,427
Non-agency mortgage-backed securities		1,157,898	1,211,607
Asset-backed securities		2,107,485	3,397,801
Other debt securities		460,136	474,858
Trading securities		28,830	43,523
Equity securities with readily determinable fair values		5,723	6,210
Private equity investments		176,667	178,127
Derivative Assets	[1]	116,876	60,492
Deferred Compensation Plan Assets		20,538	17,856
Total Assets		10,034,979	12,544,524
Derivative Liability	[1]	37,899	54,984
Deferred Compensation Liability, Current and Noncurrent		20,538	17,856
Total liabilities		58,437	72,840
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure		0	0
U.S. government and federal agency obligations		816,514	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 securities		0	0
Equity securities with readily determinable fair values		5,723	6,210
Private equity investments		0	0
Derivative Assets	[1]	0	0
Deferred Compensation Plan Assets		20,538	17,856
Total Assets		842,775	1,059,472
Derivative Liability	[1]	0	0
Deferred Compensation Liability, Current and Noncurrent		20,538	17,856
Total liabilities		20,538	17,856
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure		1,585	0
U.S. government and federal agency obligations		0	0
Government-sponsored enterprise obligations		43,962	43,108
State and municipal obligations		1,196,472	1,765,268
Agency mortgage-backed securities		3,901,346	4,308,427
Non-agency mortgage-backed securities		1,157,898	1,211,607
Asset-backed securities		2,107,485	3,397,801
Other debt securities		460,136	474,858
Trading securities		28,830	43,523
Equity securities with readily determinable fair values		0	0
Private equity investments		0	0
Derivative Assets	[1]	116,710	60,458
Deferred Compensation Plan Assets		0	0
Total Assets		9,014,424	11,305,050
Derivative Liability	[1]	37,704	54,865
Deferred Compensation Liability, Current and Noncurrent		0	0
Total liabilities		37,704	54,865
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure		0	0
U.S. government and federal agency obligations		0	0
Government-sponsored enterprise obligations		0	0
State and municipal obligations		947	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 securities		0	0
Equity securities with readily determinable fair values		0	0
Private equity investments		176,667	178,127
Derivative Assets	[1]	166	34
Deferred Compensation Plan Assets		0	0
Total Assets		177,780	180,002
Derivative Liability	[1]	195	119
Deferred Compensation Liability, Current and Noncurrent		0	0
Total liabilities		$ 195	$ 119

[1] *The fair value of each class of derivative is shown in Note 19.