Debt - Schedule of Notes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
2025 Senior Notes
Issuance of 4.50% convertible notes	$ 200,293	$ 55,000	$ 0
Debt Issuance Cost
Amortization of debt discount and debt issuance costs	995	187	$ 224
Senior Notes
2025 Senior Notes
Beginning balance	0
Issuance of 4.50% convertible notes	200,000
Ending balance	200,000	0
Discount
Beginning balance	0
Issuance of 4.50% convertible notes	(52,600)
Amortization of debt discount and debt issuance costs	5,826
Ending balance	(46,774)	0
Debt Issuance Cost
Beginning balance	0
Issuance of 4.50% convertible notes	(5,720)
Amortization of debt discount and debt issuance costs	634
Ending balance	(5,086)	0
Long-term Debt, Unclassified [Abstract]
Beginning balance	0
Issuance of 4.50% convertible notes	141,680
Amortization of debt discount and debt issuance costs	6,460
Ending balance	$ 148,140	$ 0