XML 67 R52.htm IDEA: XBRL DOCUMENT v3.20.1
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