Income taxes - Schedule of Components of Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|
Mar. 31, 2019 |
Mar. 31, 2018 |
Mar. 31, 2020 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Income Tax Disclosure [Abstract] | |||||
| Domestic | $ (21,673) | $ 24,479 | $ 17,405 | $ 22,409 | |
| Foreign | 500 | (410) | 551 | 60 | |
| Income (loss) before provision for income taxes | $ (21,173) | $ 1,123 | $ 24,069 | $ 17,956 | $ 22,469 |