Loans And Allowance For Loan Losses (Summary Of Information About The Corporation's Purchased Credit-Impaired Loans) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans And Financing Receivable [Line Items]
Balance at end of period, Contractual Receivable	$ 8,989
Acquisitions, Expected Cash Flows	6,154
Acquisitions, Carrying Amount	5,565
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	5,565
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	5,565
Balance at end of period, Carrying Amount	5,565
Contractual Receivable [Member]
Accounts, Notes, Loans And Financing Receivable [Line Items]
Balance at beginning of period, Contractual Receivable	51,693	20,356
Acquisitions, Contractual Receivable	8,989	38,890
Payments received, Contractual Receivable	(2,402)	(4,784)
Disposals/transfers, Contractual Receivable		(6,128)
Contractual interest, Contractual Receivable	855	3,359
Balance at end of period, Contractual Receivable	59,135	51,693
Non-Accretable Difference [Member]
Accounts, Notes, Loans And Financing Receivable [Line Items]
Balance at beginning of period, Non-Accretable Difference	(33,377)	(15,589)
Acquisitions, Non-Accretable Difference	(2,835)	(19,401)
Reclass from non-accretable difference, Non-Accretable Difference	117	709
Disposals/transfers, Non-Accretable Difference		4,263
Contractual interest, Non-Accretable Difference	(855)	(3,359)
Balance at end of period, Non-Accretable Difference	(36,950)	(33,377)
Expected Cash Flows [Member]
Accounts, Notes, Loans And Financing Receivable [Line Items]
Balance at beginning of period, Expected Cash Flows	18,316	4,767
Acquisitions, Expected Cash Flows	6,154	19,489
Payments received, Expected Cash Flows	(2,402)	(4,784)
Reclass from non-accretable difference, Expected Cash Flows	117	709
Disposals/transfers, Expected Cash Flows		(1,865)
Balance at end of period, Expected Cash Flows	22,185	18,316
Accretable Yield [Member]
Accounts, Notes, Loans And Financing Receivable [Line Items]
Balance at beginning of period, Accretable Yield	(2,477)	(791)
Acquisitions, Accretable Yield	(589)	(2,025)
Accretion, Accretable Yield	205	903
Reclass from non-accretable difference, Accretable Yield	(117)	(709)
Disposals/transfers, Accretable Yield		145
Balance at end of period, Accretable Yield	(2,978)	(2,477)
Carrying Amount [Member]
Accounts, Notes, Loans And Financing Receivable [Line Items]
Balance at beginning of period, Carrying Amount	15,839	3,976
Acquisitions, Carrying Amount	5,565	17,464
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	19,207	15,839
Accretion, Carrying Amount	205	194
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	5,565	17,464
Payments received, Carrying Amount	(2,402)	(4,075)
Disposals/transfers, Carrying Amount		(1,720)
Balance at end of period, Carrying Amount	$ 19,207	$ 15,839