ACQUISITIONS - Narrative (Details) - USD ($)	Dec. 01, 2016	Sep. 09, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
Fair Value, Measurements, Recurring
Business Acquisition [Line Items]
Fair value of contingent purchase price payment (up to)			$ 1,100,000	$ 7,100,000	$ 16,000,000
Holly Hunt
Business Acquisition [Line Items]
Aggregate purchase price		$ 8,500,000
Holly Hunt | Fair Value, Measurements, Recurring
Business Acquisition [Line Items]
Fair value of contingent purchase price payment (up to)			0	6,000,000
DatesWeiser
Business Acquisition [Line Items]
Aggregate purchase price	$ 11,000,000
DatesWeiser | Fair Value, Measurements, Recurring
Business Acquisition [Line Items]
Fair value of contingent purchase price payment (up to)	$ 4,000,000.0		$ 1,100,000	$ 1,100,000