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Convertible Notes, net - Additional Information (Details) - USD ($)	Nov. 08, 2018	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Convertible notes, net		$ 0	$ 258,538,000
Convertible Notes
Debt Instrument [Line Items]
Loan aggregate amount		$ 324,998,000	324,998,000
Debt instrument, stated interest rate percentage		2.00%
Debt instrument, effective interest rate percentage		16.42%
Convertible notes, net		$ 287,030,000	$ 258,538,000
Principal amount of convertible notes		$ 302,500,000
Subsequent Event \| Roll Up Loans \| Secured Debt
Debt Instrument [Line Items]
Loan aggregate amount	$ 22,500,000
Debt instrument, stated interest rate percentage	2.00%
Subsequent Event \| Bridge Credit Agreement \| Secured Debt
Debt Instrument [Line Items]
Loan aggregate amount	$ 72,500,000