Letters of Credit (Details) (Standby letter of credit facility, USD $)	Dec. 31, 2013	Dec. 31, 2012
Standby letter of credit facility
Line of Credit Facility [Line Items]
Posted letters of credit	$ 200,000	$ 200,000
Unsecured standby letter of credit facility, maximum borrowing capacity	25,100,000
Unsecured standby letter of credit facility, amount outstanding	$ 10,400,000