Income taxes - Narrative (Details) - USD ($) $ in Thousands		1 Months Ended		12 Months Ended
	Jan. 01, 2018	May 31, 2017	Jul. 31, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Operating Loss Carryforwards [Line Items]
Provision (benefit) for income taxes				$ 1,012	$ 841	$ 511
Effective tax rate (in percent)				1.00%	2.00%
Settlements and unusual provisions			$ 442
Research and development tax credit carryforwards		$ 947
Deferred tax assets				$ 91,012	$ 71,020
Deferred tax liability				32,230	20,487
Net deferred tax assets				528	450
Increase (decrease) in valuation allowance				8,200	20,300	12,100
Decrease in gross deferred tax asset due to reduction in federal corporate tax rate	$ 18,900
Earnings of foreign subsidiaries that are permanently reinvested and no U.S. income taxes have been provided				600
Unrecognized deferred tax liability related to undistributed foreign earnings				0
Unrecognized tax benefits that if recognized would affect the annual effective tax rate				100	100	1,600
Amount of possible decrease in unrecognized tax benefits within the next 12 months				100
Unrecognized tax benefits - interest and penalties expense				15	17	$ 91
Unrecognized tax benefits - interest and penalties accrued				97	$ 91
Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards				239,000
Operating loss carryforwards subject to expiration				116,300
Operating loss carryforwards not subject to expiration				122,700
Internal Revenue Service (IRS) | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research and development tax credit carryforwards				5,700
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards				12,900
State and Local Jurisdiction | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research and development tax credit carryforwards				10,100
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Deferred tax assets				867
Deferred tax liability				339
Net deferred tax assets				528
Net operating loss carryforwards				4,600
Valuation Allowance, Operating Loss Carryforwards
Operating Loss Carryforwards [Line Items]
Increase (decrease) in valuation allowance				$ 500
Tax Year 2010 - Tax Year 2012
Operating Loss Carryforwards [Line Items]
Provision (benefit) for income taxes			$ 1,000
Tax Year 2012 - Tax Year 2015
Operating Loss Carryforwards [Line Items]
Provision (benefit) for income taxes		$ (425)