Debt - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Debt Instrument [Line Items]
Amortization of debt discount and issuance costs	$ 15,295	$ 5,731	$ 31,045	$ 17,044
Capitalization of interest expense	(1,210)	(985)	(3,200)	(3,055)
Total interest expense	14,566	4,746	28,620	13,989
Credit Agreement
Debt Instrument [Line Items]
Interest on debt instruments	122	0	261	0
Convertible Debt \| 2025 Notes
Debt Instrument [Line Items]
Interest on debt instruments	$ 359	$ 0	$ 514	$ 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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