Employee savings and retirement plan (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2012
Compensation and Retirement Disclosure [Abstract]
Maximum amount of current compensation employees may contributed to their 401(k) plan as percentage of salary	100.00%
Percentage of salary employer matches	4.00%
Expense recorded for matching contributions	$ 1.6	$ 1.3	$ 1.5