Summary of significant accounting policies - ASU 2016-02 (Details) - USD ($) $ in Thousands	Apr. 01, 2019	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019
Recently Adopted Accounting Pronouncements
Lease, Practical Expedients, Package	true
Right-to-use liability		$ 4,610	$ 4,363
Property, plant and equipment, net		6,860		$ 12,159
Right-to-use asset		4,425
Lease liabilities, current		873
Lease liabilities, non-current		3,737
Accrued expenses		5,156		2,801
Deferred rent, net of current portion				24
Financing obligation				(6,561)
Accumulated deficit		$ (112,298)		$ (59,766)
ASU 2016-02
Recently Adopted Accounting Pronouncements
Right-to-use liability	$ 837
Property, plant and equipment, net	645
Right-to-use asset	789
Long term prepaid rent	5,006
Lease liabilities, current	388
Lease liabilities, non-current	449
Accrued expenses	2,777
Accumulated deficit	(59,673)
ASU 2016-02 | Adjustments
Recently Adopted Accounting Pronouncements
Property, plant and equipment, net	(11,514)
Right-to-use asset	789
Long term prepaid rent	5,006
Lease liabilities, current	388
Lease liabilities, non-current	449
Accrued expenses	(24)
Deferred rent, net of current portion	(24)
Financing obligation	6,561
Accumulated deficit	$ 93