Long-Term Debt (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Long-term debt obligation
Total debt	$ 110,250,000	$ 179,438,000
Less current maturities	12,250,000	69,188,000
Total long-term debt	98,000,000	110,250,000
2008 Term Loan Facility, due March 7, 2012
Long-term debt obligation
Basis of interest rate	LIBOR	LIBOR
Total debt	0	60,000,000
2010 Revolving Credit Facility, due August 12, 2013
Long-term debt obligation
Basis of interest rate	LIBOR	LIBOR
Total debt	0	0
Remaining borrowing capacity	60,500,000
2011 Term Loan Facility, due August 16, 2016
Long-term debt obligation
Basis of interest rate	LIBOR	LIBOR
Total debt	$ 110,250,000	$ 119,438,000
Effective rate of interest (as a percent)	2.21%