Summary of Financial Information by Reportable Segment and Product Line (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Feb. 28, 2018	Feb. 28, 2017	Aug. 31, 2017
Segment Reporting Information [Line Items]
Net sales	$ 275,165	$ 258,869	$ 564,120	$ 524,662
Operating profit (Loss)	9,589	13,199	24,262	21,670
Assets	1,480,305		1,480,305		$ 1,516,955
Impairment & divestiture charges	2,987	0	2,987	0
Industrial
Segment Reporting Information [Line Items]
Net sales	99,081	91,648	195,997	178,938
Operating profit (Loss)	16,781	18,380	35,024	37,155
Assets	324,477		324,477		329,134
Industrial Tools [Member]
Segment Reporting Information [Line Items]
Net sales	87,438	78,679	171,949	157,718
Heavy Lifting Technology [Member]
Segment Reporting Information [Line Items]
Net sales	11,643	12,969	24,048	21,220
Energy
Segment Reporting Information [Line Items]
Net sales	65,992	72,884	141,833	157,530
Operating profit (Loss)	(4,513)	(579)	(4,220)	2,632
Assets	464,018		464,018		482,963
Energy Maintenance & Integrity
Segment Reporting Information [Line Items]
Net sales	48,889	51,590	105,598	116,411
Other Energy Solutions [Member]
Segment Reporting Information [Line Items]
Net sales	17,103	21,294	36,235	41,119
Engineered Solutions
Segment Reporting Information [Line Items]
Net sales	110,092	94,337	226,290	188,194
Operating profit (Loss)	2,209	1,816	8,543	2,571
Assets	548,547		548,547		531,068
On-Highway
Segment Reporting Information [Line Items]
Net sales	59,297	50,611	124,179	102,242
Agriculture, Off-Highway and Other
Segment Reporting Information [Line Items]
Net sales	50,795	43,726	102,111	85,952
General Corporate
Segment Reporting Information [Line Items]
Operating profit (Loss)	(4,888)	$ (6,418)	(15,085)	$ (20,688)
Assets	143,263		143,263		$ 173,790
Viking [Domain]
Segment Reporting Information [Line Items]
Impairment & divestiture charges	$ 2,987		$ 2,987