Accrued expenses and other current liabilities - Summary of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2018
Operating Leased Assets [Line Items]
Accrued expenses	$ 12,518	$ 9,594	$ 8,783
Accrued compensation	9,542	3,200	1,983
Other current liabilities	1,022	1,624	1,905
Accrued expenses and other current liabilities	26,165	18,590	$ 12,671
Accrued Expenses And Other Current Liabilities
Operating Leased Assets [Line Items]
Current portion of operating lease liabilities	$ 3,083	$ 4,172