Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	May 31, 2018	Feb. 28, 2018	May 31, 2017	May 31, 2018	May 31, 2017	Aug. 31, 2018
Income Taxes [Line Items]
Income tax expense	$ 7,066		$ 5,245	$ 12,614	$ 8,331
Estimated effective income tax rate				28.50%	33.10%
Discrete income tax expense				$ 4,700
Provisional deemed repatriation transition tax obligation	1,800			1,800
Deferred income tax expense resulting from U.S. tax reform	400	$ 800
Provisional estimates incremental income tax expense resulting from U.S. tax reform	3,000	$ 3,000
U.S.tax effects of discrete non-deductible carrying value adjustment on business held for sale	$ 1,700			$ 1,700
Tax adjustment for unusual items			$ 0		$ 0
Scenario, Plan [Member]
Income Taxes [Line Items]
Blended U.S. corporate income tax rate						25.70%