Segment Data (Details) $ in Thousands	3 Months Ended	11 Months Ended	12 Months Ended
	Nov. 30, 2016 USD ($)	Aug. 31, 2017 USD ($)	Aug. 31, 2017 USD ($) item	Aug. 31, 2016 USD ($)	Aug. 31, 2015 USD ($)
Segment data
Revenues			$ 252,560	$ 238,094	$ 238,046
Income before income taxes			60,892	50,110	41,226
Total assets		$ 254,738	254,738	262,819
Interest			839	1,054	1,063
Depreciation			5,130	5,606	5,810
Amortization			$ 9,127	7,836	6,762
Number of operating segments | item			2
Gain on sale of business			$ 2,013	1,031
Inventory Step up to Fair Value			190		65
Write-down of certain assets under construction				365
Expenses related to acquisition			584		584
Income before income taxes			60,892	50,110	41,226
Gain on sale of real estate			860
Exit and demolition costs			70	935
Resin Designs
Segment data
Expenses related to acquisition	$ 584	584
Henkel Corporation ( Seller) | Selling, General and Administrative Expenses
Segment data
Expenses related to acquisition					584
Industrial Materials
Segment data
Revenues			202,956	181,728	176,547
Industrial Materials | Resin Designs
Segment data
Inventory Step up to Fair Value			190
Industrial Materials | Specialty chemical intermediates product line
Segment data
Inventory Step up to Fair Value					65
Industrial Materials | Fiber Optic Cable Components Product Line
Segment data
Gain on sale of business			2,013
Industrial Materials | RodPack Business
Segment data
Gain on sale of business				1,031
Write-down of certain assets under construction				365
Construction Materials
Segment data
Revenues			49,604	56,366	61,499
Reportable segments
Segment data
Income before income taxes			85,766	73,497	63,660
Total assets		194,425	194,425	174,986
Income before income taxes			85,766	73,497	63,660
Reportable segments | Industrial Materials
Segment data
Income before income taxes			67,561	53,530	46,388
Total assets		156,263	156,263	136,003
Interest			629	791	913
Depreciation			3,423	3,918	4,050
Amortization			7,839	6,427	5,178
Income before income taxes			67,561	53,530	46,388
Reportable segments | Construction Materials
Segment data
Total assets		38,162	38,162	38,983
Interest			210	263	150
Depreciation			718	761	1,123
Amortization			1,288	1,409	1,584
Corporate and common costs
Segment data
Income before income taxes			(24,874)	(23,387)	(22,434)
Total assets		$ 60,313	60,313	87,833
Pension related settlement costs			14
Income before income taxes			(24,874)	(23,387)	(22,434)
Corporate and common costs | Resin Designs
Segment data
Expenses related to acquisition			584
Corporate and common costs | Specialty chemical intermediates product line
Segment data
Expenses related to acquisition					584
Pension related settlement costs					188
Corporate and common costs | Randolph MA
Segment data
Exit and demolition costs			70	935
Plant closing expenses				877
Pension settlement costs				13
Corporate and common costs | Bridgewater MA location
Segment data
Gain on sale of real estate			792
Corporate and common costs | Paterson NJ
Segment data
Gain on sale of real estate			68
Corporate and common costs | Construction Materials
Segment data
Income before income taxes			18,205	19,967	17,272
Income before income taxes			$ 18,205	$ 19,967	$ 17,272