Loans And Allowance For Credit Losses (Summary Of Net Financial Impact On Interest Income Due To Interest Rate Modifications Below Market For Accruing TDR Loans) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2012		Dec. 31, 2011
Financing Receivable, Modifications [Line Items]
Net financial impact on interest income	$ (6,129)	[1]	$ (19,630)	[1]
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Net financial impact on interest income	(392)		(1,696)
Commercial [Member] | Commercial And Industrial [Member]
Financing Receivable, Modifications [Line Items]
Net financial impact on interest income	(15)		(46)
Commercial [Member] | Owner Occupied [Member]
Financing Receivable, Modifications [Line Items]
Net financial impact on interest income	(377)		(1,650)
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Net financial impact on interest income	(1,765)		(7,340)
Commercial Real Estate [Member] | Construction And Land Development [Member]
Financing Receivable, Modifications [Line Items]
Net financial impact on interest income	(219)		(244)
Commercial Real Estate [Member] | Term [Member]
Financing Receivable, Modifications [Line Items]
Net financial impact on interest income	(1,546)		(7,096)
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Net financial impact on interest income	(3,972)		(10,594)
Consumer [Member] | Home Equity Credit Line [Member]
Financing Receivable, Modifications [Line Items]
Net financial impact on interest income	(15)
Consumer [Member] | 1-4 Family Residential [Member]
Financing Receivable, Modifications [Line Items]
Net financial impact on interest income	(3,849)		(10,188)
Consumer [Member] | Construction And Other Consumer Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Net financial impact on interest income	$ (108)		$ (406)

[1] Calculated based on the difference between the modified rate and the pre-modified rate applied to the recorded investment.