WARRANTIES - Changes in Product Warranty Reserve (FY) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Balance at beginning of period	$ 153,063	$ 138,992	$ 138,992	$ 92,064
Warranty expense	45,691	33,108	50,385	28,947
Acquisitions	3,081	3,412	806	59,685
Warranty claim payments	(42,993)	(33,492)	(48,548)	(38,772)
Foreign currency impact	(4,289)	6,744	11,428	(2,932)
Balance at end of period	$ 154,553	$ 148,764	$ 153,063	$ 138,992

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

No definition available.

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- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable for estimated claims under standard and extended warranty protection rights granted to customers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=68068213&loc=d3e12565-110249

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (c)(5)
-URI http://asc.fasb.org/extlink&oid=68068213&loc=d3e12565-110249

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15(5))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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- Definition

Amount of increase in the standard and extended product warranty accrual from a business acquisition.

+ References

+ Details

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- Definition

Amount of decrease in the standard and extended product warranty accrual from payments made in cash or in kind to satisfy claims under the terms of the standard and extended product warranty.

+ References

+ Details

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- Definition

Amount of increase in the standard and extended product warranty accrual from warranties issued.

+ References

+ Details

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- Definition

Amount of foreign currency translation gain (loss) which decreases (increases) the standard and extended product warranty accrual.

+ References

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