Leases - Supplemental balance sheet information (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Mar. 31, 2019
Operating leases:
Operating lease right-of-use assets	$ 3,059
Operating lease liabilities	2,145
Operating lease liabilities	1,257
Finance leases
Finance lease liability, current	$ 85
Finance Lease, Liability, Current, Statement of Financial Position	us-gaap:OtherLiabilitiesCurrent
Finance Lease, Liability, Noncurrent	$ 299
Finance Lease, Liability, Noncurrent, Statement of Financial Position	us-gaap:OtherLiabilitiesNoncurrent
Weighted-average remaining lease term: Operating leases	1 year 7 months 6 days
Weighted-average remaining lease term: Finance leases	4 years
Weighted-average discount rate: Operating leases (as a percent)	10.30%
Weighted-average discount rate: finance leases (as a percent)	6.90%
Property and equipment, Finance lease
Finance leases
Property and equipment, gross	$ 429	$ 429
Property and equipment, accumulated depreciation	$ (50)