Employee stock ownership plan - Additional Information (Details) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended | ||
---|---|---|---|---|
Mar. 31, 2020 |
Mar. 31, 2019 |
Dec. 31, 2019 |
May 31, 2019 |
|
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items] | ||||
Annual contribution vesting percentage | 3.00% | |||
Employee stock ownership plan (ESOP), compensation expense | $ 675 | $ 1,500 | ||
Shares in ESOP | 11,653,776 | 11,790,113 | 13,443,484 | |
Employee Stock Option [Member] | ||||
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items] | ||||
Employee stock ownership plan (ESOP), compensation expense | $ 675 | $ 1,500 |