Long-Term Debt - Components of Long-Term Debt (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term debt, Amount Outstanding	$ 615,367	$ 629,756
Less current portion of long-term debt	(19,531)	(19,234)
Debt classified as long-term debt	$ 595,836	610,522
Senior Secured Notes, 7.25% [Member]
Debt Instrument [Line Items]
Interest bearing note, maturity date	Dec. 30, 2029
Long-term debt, Amount Outstanding	$ 44,969	$ 46,291
Long-term debt, Interest Rate	7.25%	7.25%
Senior Secured Notes, 6.47% [Member]
Debt Instrument [Line Items]
Interest bearing note, maturity date	Sep. 30, 2030
Long-term debt, Amount Outstanding	$ 102,650	$ 105,622
Long-term debt, Interest Rate	6.47%	6.47%
Senior Secured Notes, 8.50% [Member]
Debt Instrument [Line Items]
Interest bearing note, maturity date	Dec. 30, 2020
Long-term debt, Amount Outstanding	$ 19,063	$ 20,000
Long-term debt, Interest Rate	8.50%	8.50%
Senior Secured Notes, 5.04% [Member]
Debt Instrument [Line Items]
Interest bearing note, maturity date	Jun. 20, 2018
Long-term debt, Amount Outstanding	$ 60,000	$ 60,000
Long-term debt, Interest Rate	5.04%	5.04%
Senior Secured Credit Facilities, 2.42% [Member]
Debt Instrument [Line Items]
Interest bearing note, maturity date	Jun. 20, 2018
Long-term debt, Amount Outstanding	$ 388,685	$ 397,843
Long-term debt, Interest Rate	2.45%	2.42%