Fair Value Measurement (Schedule of Fair Value on a Nonrecurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	$ 39,400		$ 28,000
Other real estate owned	5,127		3,224
Mortgage servicing rights, Fair Value	235		368		603
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights, Fair Value	235		368
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	9,235	[1]	13,705	[1]
Other real estate owned	5,127	[1]	3,224	[1]
Mortgage servicing rights, Fair Value	235		368
Total assets	14,597		17,297
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	9,235	[1]	13,705	[1]
Other real estate owned	5,127	[1]	3,224	[1]
Mortgage servicing rights, Fair Value	235		368
Total assets	$ 14,597		$ 17,297

[1] Includes assets directly charged-down to fair value during the year-to-date period