Summary of Financial Information by Reportable Segment and Product Line (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2018	May 31, 2017	Aug. 31, 2017
Segment Reporting Information [Line Items]
Net sales	$ 317,096	$ 295,427	$ 881,216	$ 820,089
Operating profit (Loss)	32,585	27,332	56,847	49,003
Assets	1,504,785		1,504,785		$ 1,516,955
Impairment & divestiture charges		0	2,987	0
Industrial
Segment Reporting Information [Line Items]
Net sales	108,297	100,503	304,294	279,441
Operating profit (Loss)	25,999	23,705	61,023	60,860
Assets	325,291		325,291		329,134
Industrial Tools [Member]
Segment Reporting Information [Line Items]
Net sales	98,970	87,404	270,919	245,122
Heavy Lifting Technology [Member]
Segment Reporting Information [Line Items]
Net sales	9,327	13,099	33,375	34,319
Energy
Segment Reporting Information [Line Items]
Net sales	83,857	83,480	225,690	241,010
Operating profit (Loss)	6,269	905	2,050	3,537
Assets	463,026		463,026		482,963
Energy Maintenance & Integrity
Segment Reporting Information [Line Items]
Net sales	63,421	59,905	169,020	176,316
Other Energy Solutions [Member]
Segment Reporting Information [Line Items]
Net sales	20,436	23,575	56,670	64,694
Engineered Solutions
Segment Reporting Information [Line Items]
Net sales	124,942	111,444	351,232	299,638
Operating profit (Loss)	9,027	8,105	17,570	10,676
Assets	543,760		543,760		531,068
On-Highway
Segment Reporting Information [Line Items]
Net sales	66,556	57,710	190,735	159,952
Agriculture, Off-Highway and Other
Segment Reporting Information [Line Items]
Net sales	58,386	53,734	160,497	139,686
General Corporate
Segment Reporting Information [Line Items]
Operating profit (Loss)	(8,710)	$ (5,383)	(23,796)	$ (26,070)
Assets	172,708		172,708		$ 173,790
Viking [Domain]
Segment Reporting Information [Line Items]
Impairment & divestiture charges	$ 0		$ 2,987