SENIOR NOTES PAYABLE AND OTHER DEBT - Senior Notes (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	Feb. 28, 2019	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Jan. 03, 2019
Debt instruments
Senior notes payable and other debt, gross		$ 10,789,178
Loss on extinguishment of debt, net		405	$ 10,977
Proceeds from issuance of debt		706,591	$ 738,519
5.45% Senior Notes due 2043
Debt instruments
Senior notes payable and other debt, gross		0		$ 258,750
Interest rate				5.45%	5.45%
Loss on extinguishment of debt, net		400		$ 7,100
Senior notes redeemed					$ 258,800
3.50% Senior Notes due 2024
Debt instruments
Senior notes payable and other debt, gross	$ 400,000	$ 400,000		0
Interest rate	3.50%	3.50%
Public offering price as percent of par	99.88%
Proceeds from issuance of debt	$ 399,500
4.875% Senior Notes due 2049
Debt instruments
Senior notes payable and other debt, gross	$ 300,000	$ 300,000		$ 0
Interest rate	4.875%	4.875%
Public offering price as percent of par	99.77%
Proceeds from issuance of debt	$ 299,300