Debt Convertible Notes (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Dec. 08, 2014
Debt Instrument [Line Items]
Long-term debt	$ 141,946	$ 137,958
Convertible Debt [Member] | Senior 3 Point 25 Percent Convertible Notes Due 2020 [Member]
Debt Instrument [Line Items]
Principal amount of Convertible Senior Notes outstanding	172,500	172,500
Unamortized discount of liability component	(26,893)	(30,403)
Unamortized debt issuance costs		4,200
Net carrying amount of liability component	141,946	137,958
Less: current portion	0	0
Long-term debt	141,946	137,958
Carrying value of equity component, net of issuance costs	29,758	29,758	$ 30,700
Fair value of outstanding Convertible Senior Notes (2)	$ 166,023	$ 190,613
Remaining amortization period of discount on the liability component	5 years 4 months	6 years
Other Current Assets [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 300	$ 300
Other Current Assets [Member] | Senior 3 Point 25 Percent Convertible Notes Due 2020 [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs		600
Other Current Assets [Member] | Convertible Debt [Member] | Senior 3 Point 25 Percent Convertible Notes Due 2020 [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	3,661	4,139
Other non-current assets [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 300	500
Other non-current assets [Member] | Senior 3 Point 25 Percent Convertible Notes Due 2020 [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs		3,500
Scenario, previously reported [Member]
Debt Instrument [Line Items]
Long-term debt		142,097
Scenario, previously reported [Member] | Convertible Debt [Member] | Senior 3 Point 25 Percent Convertible Notes Due 2020 [Member]
Debt Instrument [Line Items]
Net carrying amount of liability component		$ 142,100