Loans And Allowance For Credit Losses (Summary Of Major Portfolio Segment And Specific Loan Class) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Provision for Loan Losses	$ 300,000	$ 200,000	$ (500,000)	$ (2,500,000)
Balance at end of period	609,375,000	675,907,000	609,375,000	675,907,000
Loans held for sale	152,448,000		152,448,000			$ 132,504,000
Commercial and industrial	13,110,925,000		13,110,925,000			13,162,955,000
Leasing	401,548,000		401,548,000			408,974,000
Owner occupied	7,277,208,000		7,277,208,000			7,351,548,000
Municipal	588,985,000		588,985,000			520,887,000
Construction and land development	2,061,716,000		2,061,716,000			1,986,408,000
Term	8,058,285,000		8,058,285,000			8,126,600,000
Provision for loan losses	(566,000)	54,416,000	928,000	55,026,000
Change In Allowance Covered By F D I C Indemnification	(38,000)	444,000	0	1,261,000
Allowance for Loan and Lease Losses, Write-offs	(31,048,000)	(23,400,000)	(51,236,000)	(44,195,000)
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	19,806,000	17,214,000	56,876,000	30,098,000
Net loan and lease charge-offs	(11,242,000)	(6,186,000)	5,640,000	(14,097,000)
Reserve for unfunded lending commitments	79,961,000	95,472,000	79,961,000	95,472,000	$ 82,287,000	81,076,000	$ 88,693,000	$ 89,705,000
Provision for Unfunded Lending Commitments	2,326,000	(6,779,000)	1,115,000	(5,767,000)
Total allowance for credit losses	689,336,000	771,379,000	689,336,000	771,379,000
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at end of period	45,809,000	45,002,000	45,809,000	45,002,000
Provision for loan losses	$ 392,000	4,570,000	(67,000)	13,549,000
Change In Allowance Covered By F D I C Indemnification		60,000	0	96,000
Allowance for Loan and Lease Losses, Write-offs	$ (3,283,000)	(4,416,000)	(6,894,000)	(7,561,000)
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	3,158,000	2,945,000	5,496,000	5,142,000
Net loan and lease charge-offs	(125,000)	(1,471,000)	(1,398,000)	(2,419,000)
Reserve for unfunded lending commitments	548,000	3,982,000	548,000	3,982,000	575,000	628,000	3,550,000	3,875,000
Provision for Unfunded Lending Commitments	27,000	(432,000)	(80,000)	107,000
Total allowance for credit losses	46,357,000	48,984,000	46,357,000	48,984,000
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at end of period	125,796,000	187,940,000	125,796,000	187,940,000
Construction and land development	2,061,716,000		2,061,716,000			1,986,408,000
Term	8,058,285,000		8,058,285,000			8,126,600,000
Provision for loan losses	(4,983,000)	20,272,000	31,870,000	23,163,000
Change In Allowance Covered By F D I C Indemnification	(57,000)	0	(57,000)	0
Allowance for Loan and Lease Losses, Write-offs	(3,943,000)	(2,961,000)	(4,569,000)	(10,815,000)
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	3,050,000	3,024,000	17,169,000	5,906,000
Net loan and lease charge-offs	(893,000)	63,000	12,600,000	(4,909,000)
Reserve for unfunded lending commitments	18,639,000	38,689,000	18,639,000	38,689,000	18,937,000	21,517,000	35,273,000	37,485,000
Provision for Unfunded Lending Commitments	298,000	(3,416,000)	(2,878,000)	1,204,000
Total allowance for credit losses	144,435,000	226,629,000	144,435,000	226,629,000
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at end of period	437,770,000	442,965,000	437,770,000	442,965,000
Commercial and industrial	13,110,925,000		13,110,925,000			13,162,955,000
Leasing	401,548,000		401,548,000			408,974,000
Owner occupied	7,277,208,000		7,277,208,000			7,351,548,000
Municipal	588,985,000		588,985,000			520,887,000
Provision for loan losses	(5,941,000)	29,574,000	(30,875,000)	18,314,000
Change In Allowance Covered By F D I C Indemnification	19,000	384,000	57,000	1,165,000
Allowance for Loan and Lease Losses, Write-offs	(23,822,000)	(16,023,000)	(39,773,000)	(25,819,000)
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	13,598,000	11,245,000	34,211,000	19,050,000
Net loan and lease charge-offs	(10,224,000)	(4,778,000)	(5,562,000)	(6,769,000)
Reserve for unfunded lending commitments	60,774,000	52,801,000	60,774,000	52,801,000	$ 62,775,000	$ 58,931,000	$ 49,870,000	$ 48,345,000
Provision for Unfunded Lending Commitments	(2,001,000)	(2,931,000)	1,843,000	4,456,000
Total allowance for credit losses	$ 498,544,000	$ 495,766,000	$ 498,544,000	$ 495,766,000