SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Goodwill and Intangible Assets (Narrative) (Details) - Developed Technology and In-process Research and Development - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2018
Indefinite-lived Intangible Assets [Line Items]
Impairment of intangible assets			$ 116.2
Valtech
Indefinite-lived Intangible Assets [Line Items]
Impairment of intangible assets	$ 116.2	$ 116.2	$ 116.2

Amount of impairment loss resulting from write-down of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16373-109275

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration