Fair Value Measurements (Summary Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($)		Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure		$ 5,570,000	$ 39,396,000
U.S. government and federal agency obligations		1,080,720,000	838,059,000
Government-sponsored enterprise obligations		51,755,000	54,485,000
State and municipal obligations		2,096,827,000	2,045,099,000
Agency mortgage-backed securities		5,683,000,000	6,712,085,000
Non-agency mortgage-backed securities		1,366,477,000	361,074,000
Asset-backed securities		3,539,219,000	1,882,243,000
Other debt securities		632,029,000	556,219,000
Trading securities		46,235,000	35,321,000
Equity securities with readily determinable fair values		7,153,000	2,966,000
Private equity investments		147,406,000	94,368,000
Derivative Assets	[1]	41,842,000	89,889,000
Deferred Compensation Plan Assets		21,794,000	19,278,000
Total Assets		14,720,027,000	12,730,482,000
Derivative Liability	[1]	12,101,000	18,675,000
Deferred Compensation Liability, Current and Noncurrent		21,794,000	19,278,000
Total liabilities		33,895,000	37,953,000
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		1,080,720,000	838,059,000
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		7,153,000	2,966,000
Private equity investments		0	0
Derivative Assets	[1]	0	0
Deferred Compensation Plan Assets		21,794,000	19,278,000
Total Assets		1,109,667,000	860,303,000
Derivative Liability	[1]	0	0
Deferred Compensation Liability, Current and Noncurrent		21,794,000	19,278,000
Total liabilities		21,794,000	19,278,000
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		5,570,000	39,396,000
U.S. government and federal agency obligations		0	0
Government-sponsored enterprise obligations		51,755,000	54,485,000
State and municipal obligations		2,094,843,000	2,037,131,000
Agency mortgage-backed securities		5,683,000,000	6,712,085,000
Non-agency mortgage-backed securities		1,366,477,000	361,074,000
Asset-backed securities		3,539,219,000	1,882,243,000
Other debt securities		632,029,000	556,219,000
Trading securities		46,235,000	35,321,000
Equity securities with readily determinable fair values		0	0
Private equity investments		0	0
Derivative Assets	[1]	40,994,000	86,447,000
Deferred Compensation Plan Assets		0	0
Total Assets		13,460,122,000	11,764,401,000
Derivative Liability	[1]	11,824,000	17,974,000
Deferred Compensation Liability, Current and Noncurrent		0	0
Total liabilities		11,824,000	17,974,000
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		1,984,000	7,968,000
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		147,406,000	94,368,000
Derivative Assets	[1]	848,000	3,442,000
Deferred Compensation Plan Assets		0	0
Total Assets		150,238,000	105,778,000
Derivative Liability	[1]	277,000	701,000
Deferred Compensation Liability, Current and Noncurrent		0	0
Total liabilities		$ 277,000	$ 701,000

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