LINES OF CREDIT - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Line Of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity				$ 1,500,000,000
Line of credit expiration date		Mar. 31, 2022
Line of credit, amount outstanding		$ 230,000,000	$ 425,000,000
Line of credit, remaining borrowing capacity		1,270,000,000
Compensating balance requirements for our letters of credit		$ 3,000,000	$ 6,000,000
Subsequent Event | Amended and Restated
Line Of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	$ 1,500,000,000
Line of credit expiration date	Jan. 31, 2025