Goodwill and Intangible Assets - Changes in Goodwill (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
Goodwill [Roll Forward]
Net goodwill, beginning balance	$ 188,841
Measurement period adjustment related to acquisition of Stromag	1,073
Impact of changes in foreign currency and other	9,072
Net goodwill, ending balance	198,986
Couplings, Clutches and Brakes [Member]
Goodwill [Roll Forward]
Net goodwill, beginning balance	104,465
Measurement period adjustment related to acquisition of Stromag	712
Impact of changes in foreign currency and other	8,213
Net goodwill, ending balance	113,390
Electromagnetic Clutches and Brakes [Member]
Goodwill [Roll Forward]
Net goodwill, beginning balance	37,161
Measurement period adjustment related to acquisition of Stromag	361
Impact of changes in foreign currency and other	286
Net goodwill, ending balance	37,808
Gearing [Member]
Goodwill [Roll Forward]
Net goodwill, beginning balance	47,215
Impact of changes in foreign currency and other	573
Net goodwill, ending balance	$ 47,788