Commitments and Contingent Liabilities (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Supply Commitment [Line Items]
Financial instruments whose contract amount represents a credit risk	$ 49,570,000	$ 35,245,000
Fixed rate loan commitments	5,100,000	2,200,000
Weighted average interest rate on fixed rate loan commitments (in hundredths)	3.40%	3.80%
Loan Repurchase Guarantee [Member]
Guarantor Obligations [Line Items]
Maximum amounts of guarantees on loans sold without recourse	365,700,000	393,100,000
Number of loans repurchased	3
Repurchase of loans sold without recourse	440,000	0
Commitments to Make Loans [Member]
Supply Commitment [Line Items]
Financial instruments whose contract amount represents a credit risk	5,075,000	2,229,000
Undisbursed Portion of Loans Closed [Member]
Supply Commitment [Line Items]
Financial instruments whose contract amount represents a credit risk	13,693,000	4,875,000
Unused Lines of Credit [Member]
Supply Commitment [Line Items]
Financial instruments whose contract amount represents a credit risk	30,224,000	27,563,000
Irrevocable Letters of Credit [Member]
Supply Commitment [Line Items]
Financial instruments whose contract amount represents a credit risk	$ 578,000	$ 578,000