Loans (Weighted Average Risk Grades For All Commercial Loans By Class) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Commercial And Industrial, Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	5.22	5.36
Loans	$ 870,586	$ 806,888
Commercial And Industrial, Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	6.55	6.75
Loans	3,046,281	2,981,770
Commercial Real Estate, Buildings, Land And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	7.14	7.29
Loans	2,585,957	2,609,494
Commercial Real Estate, Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	7.30	7.59
Loans	434,870	593,273
Risk Grades 1-8 [Member] | Commercial And Industrial, Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	5.21	5.27
Loans	868,561	786,664
Risk Grades 1-8 [Member] | Commercial And Industrial, Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	6.20	6.16
Loans	2,802,037	2,572,011
Risk Grades 1-8 [Member] | Commercial Real Estate, Buildings, Land And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	6.69	6.71
Loans	2,266,576	2,189,602
Risk Grades 1-8 [Member] | Commercial Real Estate, Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	6.95	7.10
Loans	378,530	485,455
Risk Grade 9 [Member] | Commercial And Industrial, Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	9.00	9.00
Loans	2,025	20,224
Risk Grade 9 [Member] | Commercial And Industrial, Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	9.00	9.00
Loans	55,105	95,278
Risk Grade 9 [Member] | Commercial Real Estate, Buildings, Land And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	9.00	9.00
Loans	103,894	137,314
Risk Grade 9 [Member] | Commercial Real Estate, Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	9.00	9.00
Loans	30,376	52,817
Risk Grade 10 [Member] | Commercial And Industrial, Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	10.00	10.00
Risk Grade 10 [Member] | Commercial And Industrial, Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	10.00	10.00
Loans	49,982	116,158
Risk Grade 10 [Member] | Commercial Real Estate, Buildings, Land And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	10.00	10.00
Loans	45,278	91,962
Risk Grade 10 [Member] | Commercial Real Estate, Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	10.00	10.00
Loans	16,186	32,055
Risk Grade 11 [Member] | Commercial And Industrial, Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	11.00	11.00
Risk Grade 11 [Member] | Commercial And Industrial, Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	11.00	11.00
Loans	96,046	137,923
Risk Grade 11 [Member] | Commercial Real Estate, Buildings, Land And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	11.00	11.00
Loans	126,594	126,403
Risk Grade 11 [Member] | Commercial Real Estate, Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	11.00	11.00
Loans	8,449	13,646
Risk Grade 12 [Member] | Commercial And Industrial, Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	12.00	12.00
Risk Grade 12 [Member] | Commercial And Industrial, Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	12.00	12.00
Loans	39,826	48,216
Risk Grade 12 [Member] | Commercial Real Estate, Buildings, Land And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	12.00	12.00
Loans	41,747	54,366
Risk Grade 12 [Member] | Commercial Real Estate, Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	12.00	12.00
Loans	1,329	9,300
Risk Grade 13 [Member] | Commercial And Industrial, Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	13.00	13.00
Risk Grade 13 [Member] | Commercial And Industrial, Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	13.00	13.00
Loans	3,285	12,184
Risk Grade 13 [Member] | Commercial Real Estate, Buildings, Land And Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	13.00	13.00
Loans	$ 1,868	$ 9,847
Risk Grade 13 [Member] | Commercial Real Estate, Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade	13.00	13.00