Long-term Debt - Principal Balances under Long-term Debt (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Line of Credit Facility [Line Items]
Total long-term debt	$ 248,375	$ 248,854
Less current portion	10,000	10,000
Long-term portion	238,375	238,854
Term Loan
Line of Credit Facility [Line Items]
Total long-term debt	87,500	92,500
Revolving Credit Facility
Line of Credit Facility [Line Items]
Total long-term debt	$ 160,875	$ 156,354