CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 17,350	$ 8,564	$ 45,226	$ (80,022)
Other comprehensive income (loss), net of tax:
Cumulative foreign currency translation adjustments	4,592	1,766	(164)	6,793
Unrealized gains (losses) on marketable securities, net of tax effects of $0 during each of the three and nine months ended June 30, 2017, and $0 and ($58) during the three and nine months ended June 30, 2016	4	11	2	(92)
Actuarial gains (losses), net of tax effects of $0 and $5 during the three and nine months ended June 30, 2017, $1 and $0 during the three and nine months ended June 30, 2016	2	(1)	(4)	2
Total other comprehensive income (loss), net of tax	4,598	1,776	(166)	6,703
Comprehensive income (loss)	$ 21,948	$ 10,340	$ 45,060	$ (73,319)