Interim Condensed Consolidated Balance Sheets (Parenthetical) $ in Thousands	Jun. 30, 2017 USD ($) vote / shares $ / shares shares	Sep. 30, 2016 USD ($) vote / shares $ / shares shares
Allowance for doubtful accounts | $	$ (3,279)	$ (2,370)
Class A Common Stock [Member]
Common stock, par value (usd per share) | $ / shares	$ 0.001	$ 0.001
Common stock voting right per share (votes per share) | vote / shares	1	1
Common stock, shares authorized (shares)	500,000,000	500,000,000
Common stock, shares issued (shares)	57,885,128	57,018,362
Common stock, shares outstanding (shares)	57,885,128	57,018,362
Class B Common Stock [Member]
Common stock, par value (usd per share) | $ / shares	$ 0.001	$ 0.001
Common stock voting right per share (votes per share) | vote / shares	10	10
Common stock, shares authorized (shares)	500,000,000	500,000,000
Common stock, shares issued (shares)	44,073,597	44,403,847
Common stock, shares outstanding (shares)	44,073,597	44,403,847