DEBT - Additional Information (Details)			1 Months Ended	3 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($) $ / shares shares	Feb. 15, 2019 $ / shares	May 07, 2019 USD ($)	Mar. 31, 2019 USD ($) Loan $ / shares shares	Mar. 31, 2018 $ / shares shares	Dec. 31, 2018 $ / shares
Debt Disclosure [Line Items]
Number of notes receivable pools under performance triggers | Loan				0
Dividend per share (in usd per share) | $ / shares		$ 0.45		$ 0.45	$ 0.40
Debt instrument, convertible, remaining discount amortization period	3 years 6 months
IAC Notes | Senior Notes
Debt Disclosure [Line Items]
Principal amount	$ 350,000,000			$ 350,000,000
Debt, stated interest rate	5.625%			5.625%
Exchange Notes, net | Senior Notes
Debt Disclosure [Line Items]
Debt, stated interest rate	5.625%			5.625%
Senior Unsecured Notes | Senior Notes
Debt Disclosure [Line Items]
Principal amount	$ 750,000,000			$ 750,000,000
Debt, stated interest rate	6.50%			6.50%
Convertible Notes | Convertible Debt
Debt Disclosure [Line Items]
Principal amount	$ 230,000,000			$ 230,000,000
Debt, stated interest rate	1.50%			1.50%
Debt instrument, convertible, conversion ratio				0.0000067755		0.0000067482
Debt instrument, convertible, conversion price (in usd per share) | $ / shares	$ 147.59			$ 147.59		$ 148.19
Term Loan | Corporate Credit Facility
Debt Disclosure [Line Items]
Credit facility	$ 900,000,000			$ 900,000,000
Revolving corporate credit facility, net | Corporate Credit Facility
Debt Disclosure [Line Items]
Credit facility	600,000,000			600,000,000
Revolving corporate credit facility, net | Letter of Credit | Corporate Credit Facility
Debt Disclosure [Line Items]
Credit facility	$ 75,000,000			$ 75,000,000
Convertible Note Hedges
Debt Disclosure [Line Items]
Option indexed to issuer's equity, indexed shares (in shares) | shares					1,550,000
Convertible note hedges exercised | shares	0			0
Private Warrants
Debt Disclosure [Line Items]
Number of securities called by warrants (in shares) | shares					1,550,000
Exercise price of warrants (in usd per share) | $ / shares	$ 175.97			$ 175.97	$ 175.97	$ 176.68
Number of warrants exercised | shares	0			0
Subsequent Event | Revolving corporate credit facility, net | Corporate Credit Facility
Debt Disclosure [Line Items]
Proceeds from credit facility			$ 65,000,000
Repayments of credit facility			$ 20,000,000