Debt (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				3 Months Ended	10 Months Ended	12 Months Ended			24 Months Ended
	Aug. 31, 2017	Jun. 30, 2016	Nov. 30, 2015	Oct. 31, 2015	Nov. 30, 2015	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Aug. 14, 2017	Aug. 08, 2017	Sep. 30, 2015
Debt Instrument [Line Items]
Common stock, shares issued							54,040,000	52,665,000		54,040,000
Payments of debt issuance costs							$ 287
Interest expense							4,213	$ 533	$ 3,505
Repayments of equipment financing									5,850
Amortization of debt discount							154		$ 28
Net carrying amount							73,065			$ 73,065
Line Of Credit-UBS
Debt Instrument [Line Items]
Maximum borrowing capacity													$ 50,000
Borrowings		$ 8,000	$ 10,000	$ 32,000	$ 42,000	$ 49,000
Repayments		$ 1,000
Outstanding balance							50,100			50,100
Accrued interest							1,000	$ 600
Debt, interest accrued							$ 1,100
Interest paid										500
Line Of Credit-UBS | 30-day LIBOR
Debt Instrument [Line Items]
Spread on interest rate (as a percent)							1.10%
2017 Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 100,000
Available borrowing capacity	75,000						$ 75,000			75,000
Remaining borrowing capacity	$ 25,000
Repayments							0
Additional interest in the event of default (as a percent)	3.00%
Common stock, shares issued	300,000										300,000
Debt instrument, fee amount	$ 2,400
Stock price												$ 8.16
Interest expense							3,200
Amortization of debt discount							100
Debt discount	2,700						600			600
Debt, increase (decrease)	$ (2,000)
Less: unamortized debt discount							(1,935)			(1,935)
Net carrying amount							$ 73,065			$ 73,065
2017 Term Loan | Minimum
Debt Instrument [Line Items]
Prepayment premium (as a percent)	2.50%
2017 Term Loan | Maximum
Debt Instrument [Line Items]
Prepayment premium (as a percent)	12.50%
2017 Term Loan | Base Rate
Debt Instrument [Line Items]
Spread on interest rate (as a percent)	8.75%
Base interest rate (as a percent)	1.00%