ACQUISITIONS (Details) - USD ($)				3 Months Ended		12 Months Ended
	Feb. 11, 2020	Oct. 22, 2019	Jun. 12, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill				$ 1,873,987,000		$ 1,882,020,000	$ 1,611,535,000
Cash paid for acquisitions, net of cash acquired				432,000	$ 0
Goodwill acquired				432,000		$ 267,804,000
RentPath [Member]
Business Acquisition [Line Items]
Aggregate purchase price	$ 588,000,000
Restricted cash				$ 59,000,000
STR Inc and STR Global Ltd [Member]
Business Acquisition [Line Items]
Aggregate purchase price		$ 435,000,000
Goodwill		261,868,000
Transaction costs		2,000,000
Employee retention bonus		$ 15,000,000
Requisite service period		1 year
Off Campus Partners [Member]
Business Acquisition [Line Items]
Cash paid for acquisitions, net of cash acquired			$ 16,000,000
Initial payments to acquire businesses, net of cash acquired			14,000,000
Goodwill acquired			8,000,000
Finite-lived intangible assets acquired			$ 9,000,000
North America [Member] | STR Inc and STR Global Ltd [Member]
Business Acquisition [Line Items]
Goodwill		$ 159,000,000
Finite-lived intangible assets acquired		131,000
International [Member] | STR Inc and STR Global Ltd [Member]
Business Acquisition [Line Items]
Goodwill		103,000,000
Finite-lived intangible assets acquired		$ 47,000