Quarterly financial data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 16,619	$ 13,823	$ 39,080	$ 36,658	$ 40,291	$ 35,065	$ 52,001	$ 42,227	$ 106,180	$ 169,584	$ 183,346
Gross profit	5,767	5,603	16,769	15,811	17,826	17,398	23,274	18,751	43,950	77,249	82,549
Net loss	$ (26,605)	$ (30,763)	$ (15,652)	$ (16,098)	$ (12,810)	$ (13,694)	$ (11,423)	$ (9,335)	$ (89,118)	$ (47,262)	$ (35,321)
Net loss per share:
Basic and diluted (in dollars per share)	$ (0.59)	$ (0.69)	$ (0.35)	$ (0.37)	$ (0.29)	$ (0.31)	$ (0.26)	$ (0.22)