Fair Value Measurements (Summary Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($)		Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure		$ 0	$ 5,570,000
U.S. government and federal agency obligations		1,035,406,000	1,080,720,000
Government-sponsored enterprise obligations		43,108,000	51,755,000
State and municipal obligations		1,767,109,000	2,096,827,000
Agency mortgage-backed securities		4,308,427,000	5,683,000,000
Non-agency mortgage-backed securities		1,211,607,000	1,366,477,000
Asset-backed securities		3,397,801,000	3,539,219,000
Other debt securities		474,858,000	632,029,000
Trading securities		43,523,000	46,235,000
Equity securities with readily determinable fair values		6,210,000	7,153,000
Private equity investments		178,127,000	147,406,000
Derivative Assets	[1]	60,492,000	41,842,000
Deferred Compensation Plan Assets		17,856,000	21,794,000
Total Assets		12,544,524,000	14,720,027,000
Derivative Liability	[1]	54,984,000	12,101,000
Deferred Compensation Liability, Current and Noncurrent		17,856,000	21,794,000
Total liabilities		72,840,000	33,895,000
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		1,035,406,000	1,080,720,000
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		6,210,000	7,153,000
Private equity investments		0	0
Derivative Assets	[1]	0	0
Deferred Compensation Plan Assets		17,856,000	21,794,000
Total Assets		1,059,472,000	1,109,667,000
Derivative Liability	[1]	0	0
Deferred Compensation Liability, Current and Noncurrent		17,856,000	21,794,000
Total liabilities		17,856,000	21,794,000
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		0	5,570,000
U.S. government and federal agency obligations		0	0
Government-sponsored enterprise obligations		43,108,000	51,755,000
State and municipal obligations		1,765,268,000	2,094,843,000
Agency mortgage-backed securities		4,308,427,000	5,683,000,000
Non-agency mortgage-backed securities		1,211,607,000	1,366,477,000
Asset-backed securities		3,397,801,000	3,539,219,000
Other debt securities		474,858,000	632,029,000
Trading securities		43,523,000	46,235,000
Equity securities with readily determinable fair values		0	0
Private equity investments		0	0
Derivative Assets	[1]	60,458,000	40,994,000
Deferred Compensation Plan Assets		0	0
Total Assets		11,305,050,000	13,460,122,000
Derivative Liability	[1]	54,865,000	11,824,000
Deferred Compensation Liability, Current and Noncurrent		0	0
Total liabilities		54,865,000	11,824,000
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		1,841,000	1,984,000
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		178,127,000	147,406,000
Derivative Assets	[1]	34,000	848,000
Deferred Compensation Plan Assets		0	0
Total Assets		180,002,000	150,238,000
Derivative Liability	[1]	119,000	277,000
Deferred Compensation Liability, Current and Noncurrent		0	0
Total liabilities		$ 119,000	$ 277,000

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