Debt - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Interest Expense	$ 3,506	$ 3,486	$ 3,406	$ 3,396	$ 3,462	$ 3,595	$ 2,378	$ 810	$ 13,794	$ 10,245	$ 3,471
Convertible Senior Notes | Convertible debt
Debt Instrument [Line Items]
Contractual interest expense									324	209
Amortization of debt discount									11,683	7,192
Amortization of issuance costs									1,105	689
Interest Expense									$ 13,112	$ 8,090