Debt - Convertible Senior Subordinated Notes (Details)	9 Months Ended
	Sep. 30, 2016 USD ($) shares $ / shares	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Long-term Debt	$ 198,461,000	$ 211,132,000
Decrease in notes payable	3,800,000
Senior Subordinated Notes | 2018 Notes
Debt Instrument [Line Items]
Long-term Debt	$ 50,389,000	61,632,000
Effective interest rate	6.00%
Conversion rate | shares	121.1240
Principal amount of convertible notes, denominator	$ 1,000
Conversion price (in dollars per share) | $ / shares	$ 8.26
Conversion of stock conversion price (in dollars per share) | $ / shares	$ 83.33
Senior Subordinated Notes | 2019 Notes
Debt Instrument [Line Items]
Long-term Debt	$ 148,072,000	$ 149,500,000
Effective interest rate	5.00%
Conversion rate | shares	75.7576
Conversion price (in dollars per share) | $ / shares	$ 13.20
Conversion of stock conversion price (in dollars per share) | $ / shares	$ 83.33
Accrued Liabilities [Member]
Debt Instrument [Line Items]
Accrued debt conversion liability	$ 1,100,000