BUSINESS COMBINATIONS - 2019 Acquisitions (Details) - USD ($) $ in Thousands			9 Months Ended
May 31, 2019	Mar. 01, 2019	Sep. 30, 2019
Business Acquisition [Line Items]
Goodwill recognized			$ 12,739
Private Held Company
Business Acquisition [Line Items]
Purchase price	$ 14,900	$ 10,400
Goodwill recognized	$ 7,500	$ 5,200

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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