Debt - Schedule of Interest Expense Recognized (Details) - Convertible Debt - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Schedule of Debt Cost and Interest Expense Recognized [Line Items]
Debt interest rate	1.50%		1.50%		5.75%
Contractual interest expense at 1.5% and 5.75% per annum	$ 4,313	$ 5,261	$ 8,625	$ 10,522
Amortization of debt issuance costs	632	954	1,255	1,870
Accretion of debt discount	411	2,542	815	5,052
Total	$ 5,356	$ 8,757	$ 10,695	$ 17,444