Fair Value Measurements (Schedule of Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period			$ 725				$ 1,241
Gains and losses (realized and unrealized): included in earnings			(11)	[1]			(506)	[1]
Gains and losses (realized and unrealized): Included in other comprehensive income			182				161
Balance at end of period			896				896
Derivative Assets / Liabilities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period			(27)	[2]			435	[3]
Gains and losses (realized and unrealized): included in earnings			(11)	[1],[2]			(473)	[1],[2]
Gains and losses (realized and unrealized): Included in other comprehensive income			0	[2]			0	[2]
Balance at end of period			(38)	[2]			(38)	[2]
Securities Available for Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	749	[3]	752	[3]	887	[3]	806	[3]
Gains and losses (realized and unrealized): Included in earnings	0	[1],[3]	0	[1],[3]	(209)	[1],[3]	(33)	[1],[3]
Gains and losses (realized and unrealized): Included in other comprehensive income	18	[3]	182	[3]	89	[3]	161	[3]
Balance at end of period	$ 767	[3]	$ 934	[3]	$ 767	[3]	$ 934	[3]

[1] Losses included in earnings for Level 3 securities available for sale consisted of credit-related impairment losses on two Level 3 pooled trust preferred debt securities. No credit-related impairment losses were recognized during the three months ended June 30, 2012 and 2011. Credit-related impairment losses of $209 thousand and $33 thousand were recognized during the six months ended June 30, 2012 and 2011, respectively. The losses included in earnings for Level 3 derivative assets and liabilities, which were comprised of forward loan commitments (interest rate lock commitments and commitments to sell fixed-rate residential mortgages), were included in net gains on loan sales and commissions on loans originated for others in the Consolidated Statements of Income.

[2] During the periods indicated, Level 3 derivative assets / liabilities consisted of forward loan commitments (interest rate lock commitments and commitments to sell fixed-rate residential mortgages). After evaluating forward loan commitments during the third quarter of 2011, it was determined that significant inputs and significant value drivers were observable in active markets, and the Corporation therefore reclassified these derivatives from out of Level 3 into Level 2.

[3] During the periods indicated, Level 3 securities available for sale were comprised of two pooled trust preferred debt securities, in the form of collateralized debt obligations.