Credit Facilities (Details)			3 Months Ended		6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 10, 2013 USD ($) $ / shares $ / securities	Dec. 03, 2013 USD ($)	Jun. 30, 2015 USD ($) $ / shares	Mar. 31, 2015 USD ($)	Jun. 30, 2015 USD ($) d $ / shares	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Line of Credit Facility [Line Items]
Convertible notes			$ 72,156,000		$ 72,156,000			$ 70,407,000
Deferred finance costs, noncurrent, net			2,200,000		2,200,000
Payments of derivative issuance costs	$ 7,400,000
Revolving Credit Facility | Wells Fargo Bank
Line of Credit Facility [Line Items]
Aggregate maximum borrowing capacity		$ 20,000,000
Minimum current ratio		2.0
Revolving Credit Facility | Wells Fargo Bank | Measurement Period One
Line of Credit Facility [Line Items]
Maximum operating loss				$ 13,500,000
Revolving Credit Facility | Wells Fargo Bank | Measurement Period Two
Line of Credit Facility [Line Items]
Maximum operating loss					23,000,000
Revolving Credit Facility | Bank of America
Line of Credit Facility [Line Items]
Aggregate maximum borrowing capacity			$ 20,000,000		20,000,000
Minimum current ratio			1.5
Letter of Credit | Wells Fargo Bank
Line of Credit Facility [Line Items]
Aggregate maximum borrowing capacity		$ 7,500,000.0
Letter of Credit | Bank of America
Line of Credit Facility [Line Items]
Aggregate maximum borrowing capacity			$ 10,000,000		$ 10,000,000
Convertible Senior Notes Issued December, 2013 | Convertible Debt
Line of Credit Facility [Line Items]
Debt instrument face amount	86,250,000
Proceeds from convertible debt	$ 82,600,000
Conversion of convertible securities					41.6051
Redemption price percentage					100.00%
Violation or event of default, declaration by note holders, percentage					25.00%
Fair value disclosure			66,900,000		$ 66,900,000
Beneficial conversion feature					19,300,000
Unamortized discount			$ 3,700,000		$ 3,700,000
Convertible conversion price | $ / shares	$ 24.04		$ 24.04		$ 24.04
Cap price | $ / securities	29.02
Redemption, Period One | Convertible Senior Notes Issued December, 2013 | Convertible Debt
Line of Credit Facility [Line Items]
Threshold trading days | d					20
Threshold consecutive trading days					30 days
Threshold percentage of stock price trigger					130.00%
Redemption price percentage					100.00%
Redemption, Period Two | Convertible Senior Notes Issued December, 2013 | Convertible Debt
Line of Credit Facility [Line Items]
Threshold trading days | d					20
Threshold consecutive trading days					30 days
Threshold percentage of stock price trigger					98.00%
Threshold business days | d					5
Threshold consecutive business days					5 years
Other Assets | Convertible Senior Notes Issued December, 2013 | Convertible Debt
Line of Credit Facility [Line Items]
Unamortized discount			$ 2,900,000		$ 2,900,000
Additional Paid-in Capital | Convertible Senior Notes Issued December, 2013 | Convertible Debt
Line of Credit Facility [Line Items]
Unamortized discount			800,000		$ 800,000
Minimum | Revolving Credit Facility | Bank of America
Line of Credit Facility [Line Items]
Credit Derivative, Liquidation Proceeds, Monetary Amount			$ 30,000,000
Forecast | Revolving Credit Facility | Wells Fargo Bank | Measurement Period Three
Line of Credit Facility [Line Items]
Maximum operating loss						$ 35,000,000
Maximum annual capital expenditures							$ 6,000,000
Forecast | Revolving Credit Facility | Wells Fargo Bank | Measurement Period Four
Line of Credit Facility [Line Items]
Maximum annual capital expenditures							3,000,000
Forecast | Minimum | Convertible Senior Notes Issued December, 2013 | Convertible Debt
Line of Credit Facility [Line Items]
Periodic interest payment							5,700,000
Forecast | Maximum | Convertible Senior Notes Issued December, 2013 | Convertible Debt
Line of Credit Facility [Line Items]
Periodic interest payment							$ 6,900,000
Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) | 2.25 % Convertible Senior Notes due 2018 | Convertible Debt
Line of Credit Facility [Line Items]
Stated interest rate			2.25%		2.25%