Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan servicing rights	$ 1,110	$ 765	$ 757	$ 802
Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	9,550	10,391
Loan servicing rights		765
Property acquired through foreclosure or repossession	1,073	1,758
Total assets at fair value on a nonrecurring basis	10,623	12,914
Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Loan servicing rights		0
Property acquired through foreclosure or repossession	0	0
Total assets at fair value on a nonrecurring basis	0	0
Nonrecurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	0	0
Loan servicing rights		0
Property acquired through foreclosure or repossession	0	0
Total assets at fair value on a nonrecurring basis	0	0
Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	9,550	10,391
Loan servicing rights		765
Property acquired through foreclosure or repossession	1,073	1,758
Total assets at fair value on a nonrecurring basis	$ 10,623	$ 12,914