Nature of Operations and Summary of Significant Accounting Policies - Goodwill (Details) $ in Thousands	3 Months Ended
Mar. 31, 2018 USD ($)
Goodwill [Roll Forward]
Gross Balance, Beginning Balance	$ 353,510
Accumulated impairment losses	(85,509)
Net Balance, Beginning Balance	268,001
Acquisitions	(384)
Currency translation	1,897
Total 2018 adjustments	1,513
Gross Balance, Ending Balance	355,023
Accumulated impairment losses	(85,509)
Net Balance, Ending Balance	269,514
Operating Segment [Member] \| Papermaking Systems [Member]
Goodwill [Roll Forward]
Gross Balance, Beginning Balance	247,014
Accumulated impairment losses	(85,509)
Net Balance, Beginning Balance	161,505
Acquisitions	(309)
Currency translation	2,131
Total 2018 adjustments	1,822
Gross Balance, Ending Balance	248,836
Accumulated impairment losses	(85,509)
Net Balance, Ending Balance	163,327
Operating Segment [Member] \| Wood Processing Systems [Member]
Goodwill [Roll Forward]
Gross Balance, Beginning Balance	106,496
Accumulated impairment losses	0
Net Balance, Beginning Balance	106,496
Acquisitions	(75)
Currency translation	(234)
Total 2018 adjustments	(309)
Gross Balance, Ending Balance	106,187
Accumulated impairment losses	0
Net Balance, Ending Balance	$ 106,187

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-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

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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.

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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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Amount before 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.

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

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Amount of increase (decrease) 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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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

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