Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified		3 Months Ended			3 Months Ended
	Mar. 31, 2013 charge_count	Mar. 31, 2013 Maximum	Mar. 31, 2013 Minimum	Sep. 30, 2012 Distinctive Notes lawsuit	Mar. 31, 2013 Roseman v. Martin Sigillito Minimum	Mar. 31, 2013 BJD, LLC and Barbara Dunning v. Enterprise Financial	Mar. 31, 2013 Commitments to extend credit	Dec. 31, 2012 Commitments to extend credit	Mar. 31, 2013 Standby letters of credit	Dec. 31, 2012 Standby letters of credit	Mar. 31, 2013 Unadvanced Commitment on Impaired Loan	Mar. 31, 2013 Fixed Rate Loan Commitment Commitments to extend credit	Dec. 31, 2012 Fixed Rate Loan Commitment Commitments to extend credit
Schedule of Commitments [Line Items]
Loans and Leases Receivable, Impaired Loans, Commitment to Lend											$ 127
Estimated losses attributable to unadvanced commitments on impaired loans											20
Off-balance sheet financial instruments, contractual amounts							741,843	722,325	46,062	42,561		39,300	50,700
Remaining term of letters of credit		5 years	6 months
Number of lawsuits, bank as defendant				2
Loss contingency, damages sought, value					$ 44,000	$ 800
Interest rate on damages sought						9.00%
Number of counts found guilty	20