Debt - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Debt Instrument [Line Items]
Amortization of debt discount and issuance costs	$ 9,917	$ 5,681	$ 15,749	$ 11,313
Capitalization of interest expense	(1,008)	(1,035)	(1,990)	(2,070)
Total interest expense	9,204	4,646	14,054	9,243
Credit Agreement
Debt Instrument [Line Items]
Interest on debt instruments	139	0	139	0
Convertible Debt \| 2025 Notes
Debt Instrument [Line Items]
Interest on debt instruments	$ 156	$ 0	$ 156	$ 0

Increase for accrued, but unpaid interest on the debt instrument for the period.

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Amount of the cost of borrowed funds accounted for as interest expense.

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