EARNINGS PER SHARE - Narrative (Details) - $ / shares	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Former IAC
Antidilutive Securities Excluded from Computation of Earnings Per Share
Average share price (in dollars per share)	$ 235.09	$ 223.89	$ 167.61
Exchangeable Notes | Former IAC
Antidilutive Securities Excluded from Computation of Earnings Per Share
Potentially dilutive securities excluded from the calculation of diluted earnings per share (in shares)		2,400,000	700,000
Common Stock $0.001 Par Value
Antidilutive Securities Excluded from Computation of Earnings Per Share
Number of shares issued upon Separation per former class A common stock				2.1584