INTANGIBLE ASSETS AND GOODWILL - Changes in Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Dec. 31, 2019	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Goodwill balance before cumulative loss on impairment as of January 1,	$ 1,024,467		$ 1,024,467	$ 982,663
Accumulated loss on impairment as of January 1,	(980,547)		(980,547)	$ (443,194)
Goodwill beginning balance after cumulative loss on impairment as of January 1,		$ 43,920	539,469
Loss on impairment during year	(537,400)	0	(537,353)
Dispositions		0	(4,862)
Acquisitions		0	46,666
Measurement period adjustments to acquired goodwill		(28)	0
Ending period balance	$ 43,920	$ 43,892	$ 43,920