Restructuring and other related costs - Restructuring related liabilities (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 |
|
| Restructuring Reserve [Roll Forward] | |||||
| Restructuring (income) loss | $ 22,176 | $ 0 | $ (5,982) | $ 0 | $ 0 |
| Employee severance and related expenses | |||||
| Restructuring Reserve [Roll Forward] | |||||
| Beginning balance | 0 | 96 | |||
| Restructuring (income) loss | 600 | (22) | |||
| Cash disbursements | (504) | (74) | |||
| Ending balance | 96 | 0 | 0 | ||
| Other costs | |||||
| Restructuring Reserve [Roll Forward] | |||||
| Beginning balance | 0 | 675 | |||
| Restructuring (income) loss | 1,118 | 1,634 | |||
| Cash disbursements | (443) | (2,309) | |||
| Ending balance | 675 | 0 | 0 | ||
| Employee severance and related expenses and other costs | |||||
| Restructuring Reserve [Roll Forward] | |||||
| Beginning balance | 0 | 771 | |||
| Restructuring (income) loss | 1,718 | 1,612 | |||
| Cash disbursements | (947) | (2,383) | |||
| Ending balance | $ 771 | $ 0 | $ 0 | ||