Goodwill and Intangible Assets - Changes in Goodwill (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($)
Goodwill [Roll Forward]
Net goodwill, beginning balance	$ 188,841
Measurement period adjustment related to acquisition of Stromag, including working capital settlement	851
Impact of changes in foreign currency and other	13,882
Net goodwill, ending balance	203,574
Couplings, Clutches and Brakes [Member]
Goodwill [Roll Forward]
Net goodwill, beginning balance	104,465
Measurement period adjustment related to acquisition of Stromag, including working capital settlement	738
Impact of changes in foreign currency and other	12,378
Net goodwill, ending balance	117,581
Electromagnetic Clutches and Brakes [Member]
Goodwill [Roll Forward]
Net goodwill, beginning balance	37,161
Measurement period adjustment related to acquisition of Stromag, including working capital settlement	113
Impact of changes in foreign currency and other	623
Net goodwill, ending balance	37,897
Gearing [Member]
Goodwill [Roll Forward]
Net goodwill, beginning balance	47,215
Impact of changes in foreign currency and other	881
Net goodwill, ending balance	$ 48,096