Summary of business and significant accounting policies - Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Deferred rent related to tenant improvement lease incentives and graduated rent payments	$ 1,300	$ 5,500
Restructuring plan initiated in the fourth quarter of fiscal year 2014
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	27	2,644	$ 4,869
Restructuring plan initiated in the fourth quarter of fiscal year 2014 | Facility Closing
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 20	$ 2,644	$ 2,743