Commitments and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 item	Dec. 31, 2012	Dec. 31, 2011
Commitments and Contingencies
Rent expense under operating leases	$ 13,500,000	$ 11,100,000	$ 9,700,000
Minimum sublease rentals due in the future	5,900,000
Repurchase of loan as a result of recourse provisions, number	1
Repurchase of loan as a result of recourse provisions, amount	494,000
Principal balance of loans sold with recourse provisions	358,100,000	342,200,000
Outstanding standby letters of credit	$ 513,000	$ 213,000
Maximum
Commitments and Contingencies
Standby letters of credit, term extended by guarantee	1 year