Goodwill and Intangible Assets - Changes in Goodwill (Detail) $ in Thousands	6 Months Ended
Jun. 30, 2018 USD ($)
Goodwill [Roll Forward]
Net goodwill, beginning balance	$ 206,040
Acquisition of Aluminum Die Casting	958
Impact of changes in foreign currency	(3,706)
Net goodwill, ending balance	203,292
Couplings, Clutches and Brakes [Member]
Goodwill [Roll Forward]
Net goodwill, beginning balance	119,963
Acquisition of Aluminum Die Casting	958
Impact of changes in foreign currency	(3,296)
Net goodwill, ending balance	117,625
Electromagnetic Clutches and Brakes [Member]
Goodwill [Roll Forward]
Net goodwill, beginning balance	37,905
Impact of changes in foreign currency	(120)
Net goodwill, ending balance	37,785
Gearing [Member]
Goodwill [Roll Forward]
Net goodwill, beginning balance	48,172
Impact of changes in foreign currency	(290)
Net goodwill, ending balance	$ 47,882

Goodwill foreign currency divestiture and other adjustments.

No definition available.

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- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

+ Details

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- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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