Fair Value Measurement (Details 3) - USD ($)	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Fair Value Measurement
Long-term debt	$ (258,684,000)		$ (253,400,000)
Nonrecurring
Fair Value Measurement
Impairment charges	0	$ 0
Carrying Amount
Fair Value Measurement
Cash and cash equivalents	23,786,000		18,196,000
Fair Value
Fair Value Measurement
Cash and cash equivalents	23,786,000		18,196,000
Senior credit facility, net of discount
Fair Value Measurement
Long-term debt	(256,517,000)		(251,010,000)
Senior credit facility, net of discount | Carrying Amount
Fair Value Measurement
Long-term debt	(258,684,000)		(253,400,000)
Senior credit facility, net of discount | Fair Value
Fair Value Measurement
Long-term debt	(258,684,000)		(253,400,000)
Other obligations
Fair Value Measurement
Long-term debt	$ (2,167,000)		$ (2,390,000)