Short-term and Long-term Debt - Line of Credit (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Line of Credit Facility [Line Items]
Line of credit amount	$ 5,209,000
Revolving line of credit
Line of Credit Facility [Line Items]
Line of credit amount	30,000,000
Line of credit outstanding balance	0	0
Tangible net worth	326,218,000
Liquid Assets	57,095,000
Revolving line of credit | Minimum
Line of Credit Facility [Line Items]
Minimum tangible net worth required	225,000,000
Liquid assets	25,000,000
Revolving line of credit | Selected LIBOR rate
Line of Credit Facility [Line Items]
Interest rate on line of credit, variable rate	1.75%
Revolving line of credit | LIBOR for a fixed rate term
Line of Credit Facility [Line Items]
Interest rate on line of credit, variable rate	1.50%
Line of Credit
Line of Credit Facility [Line Items]
Line of credit amount	$ 87,095,000