Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions (Details) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Not designated as hedging instruments
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Asset Derivatives, Fair Value	$ 2,788,000	$ 3,179,000
Liability Derivatives, Fair Value	2,299,000	3,202,000
Interest rate swap
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Financial instruments with off-balance sheet risk and derivative transactions	5,100,000	5,200,000
Investment securities pledged with financial institutions, number	2
Interest rate swap | Not designated as hedging instruments
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Weighted average maturity	1 year 5 months 23 days	2 years 2 months 26 days
Notional or Contractual Amount	114,693,000	117,756,000
Asset Derivatives, Fair Value	2,238,000	3,072,000
Liability Derivatives, Fair Value	2,299,000	3,152,000
Commitments | Not designated as hedging instruments
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Notional or Contractual Amount	255,438,000	237,970,000
Asset Derivatives, Fair Value	550,000	107,000
Forward contracts | Not designated as hedging instruments
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Notional or Contractual Amount	44,500,000	26,000,000
Liability Derivatives, Fair Value		$ 50,000