Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 537,493	$ 501,432	$ 538,551
Other comprehensive income (loss) before reclassifications	(2,237)	4,188	(2,669)
Income tax benefit (expense)	172	(194)	167
Other comprehensive income (loss) before reclassifications, net of tax	(2,065)	3,994	(2,502)
Amounts reclassified from accumulated other comprehensive loss	536	851	1,000
Income tax benefit	(415)	(23)	(91)
Amounts reclassified from accumulated other comprehensive loss, net of tax	121	828	909
Total other comprehensive income (loss), net of tax	(1,944)	4,822	(1,593)
Ending Balance	670,110	537,493	501,432
Foreign Currency Translation Adjustments
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(31,828)	(34,539)	(34,009)
Other comprehensive income (loss) before reclassifications	(2,301)	2,711	(530)
Income tax benefit (expense)	0	0	0
Other comprehensive income (loss) before reclassifications, net of tax	(2,301)	2,711	(530)
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Income tax benefit	0	0	0
Amounts reclassified from accumulated other comprehensive loss, net of tax	0	0	0
Total other comprehensive income (loss), net of tax	(2,301)	2,711	(530)
Ending Balance	(34,129)	(31,828)	(34,539)
Pension Obligations, net
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(3,465)	(5,576)	(4,273)
Other comprehensive income (loss) before reclassifications	64	1,477	(2,139)
Income tax benefit (expense)	172	(194)	167
Other comprehensive income (loss) before reclassifications, net of tax	236	1,283	(1,972)
Amounts reclassified from accumulated other comprehensive loss	536	851	688
Income tax benefit	(415)	(23)	(19)
Amounts reclassified from accumulated other comprehensive loss, net of tax	121	828	669
Total other comprehensive income (loss), net of tax	357	2,111	(1,303)
Ending Balance	(3,108)	(3,465)	(5,576)
Net Unrealized Gain (Loss) on Cash Flow Hedges
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	0	0	(240)
Other comprehensive income (loss) before reclassifications	0	0	0
Income tax benefit (expense)	0	0	0
Other comprehensive income (loss) before reclassifications, net of tax	0	0	0
Amounts reclassified from accumulated other comprehensive loss	0	0	312
Income tax benefit	0	0	(72)
Amounts reclassified from accumulated other comprehensive loss, net of tax	0	0	240
Total other comprehensive income (loss), net of tax	0	0	240
Ending Balance	0	0	0
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(35,293)	(40,115)	(38,522)
Ending Balance	$ (37,237)	$ (35,293)	$ (40,115)