Debt - Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Convertible Debt
Debt Instrument [Line Items]
Contractual interest expense	$ 5,782	$ 5,782
Amortization of debt discount	7,821	7,822
Amortization of debt issuance costs	459	459
Total interest expense	14,062	14,063
Term Loan | Secured Debt
Debt Instrument [Line Items]
Contractual interest expense	4,789	4,684
Amortization of debt discount	1,331	1,331
Amortization of debt issuance costs	161	160
Total interest expense	$ 6,281	$ 6,175