Restructuring and other related costs - Restructuring related liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Employee severance and related expenses
Restructuring Reserve [Roll Forward]
Beginning balance	$ 0	$ 96
Costs incurred	0	(22)
Cash disbursements	0	(74)
Other adjustments	0	0
Ending balance	0	0
Other costs
Restructuring Reserve [Roll Forward]
Beginning balance	318	675
Costs incurred	898	1,765
Cash disbursements	(373)	(1,466)
Other adjustments	(6)	(137)
Ending balance	837	837
Total
Restructuring Reserve [Roll Forward]
Beginning balance	318	771
Costs incurred	898	1,743
Cash disbursements	(373)	(1,540)
Other adjustments	(6)	(137)
Ending balance	$ 837	$ 837