Income taxes (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Jun. 30, 2017
Operating Loss Carryforwards [Line Items]
Provision (benefit) for income taxes		$ 330	$ 663	$ 611	$ 805
Effective tax rate (percentage)				(1.00%)	(2.00%)
Unrecognized tax benefit		3,600		$ 3,600		$ 3,000
Unrecognized tax benefits that would affect effective tax rate		98		98		124
Interest and penalties related to unrecognized tax positions accrued		93		$ 93		91
Valuation allowance						$ 50,100
Decrease in gross deferred tax asset due to reduction in federal corporate tax rate		$ 18,800
State and Local Jurisdiction | New York State Division of Taxation and Finance | Tax Year 2010 - Tax Year 2012
Operating Loss Carryforwards [Line Items]
Provision (benefit) for income taxes	$ (1,000)