BUSINESS COMBINATIONS - Preliminary purchase price allocation and period adjustment (Details) - USD ($) $ in Thousands	6 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Oct. 16, 2019	Dec. 31, 2018
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill	$ 43,892	$ 43,892	$ 43,920		$ 539,469
Period Adjustment
Goodwill	(28)		$ 0
Cadence13
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Total tangible property	654	654		$ 654
Operating lease right-of-use asset	62	62		62
Deferred tax asset	2,928	2,928		2,900
Goodwill	31,364	31,364		31,392
Total tangible and other assets	40,331	40,331		40,331
Operating lease liabilities	(985)	(985)		(985)
Net working capital	(757)	(757)		(757)
Preliminary fair value of net assets acquired	39,243	39,243		39,243
Period Adjustment
Total tangible property		0
Operating lease right-of-use asset		0
Deferred tax asset		28
Goodwill		(28)
Total tangible and other assets		0
Operating lease liabilities		0
Net working capital		0
Preliminary fair value of net assets acquired		0
Cadence13 | Trademarks and Trade Names
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Cadence13 brand	$ 5,977	5,977		$ 5,977
Period Adjustment
Cadence13 brand		$ 0