REVENUE RECOGNITION AND RECEIVABLES - Allowance for Credit Losses - (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Allowance for Credit Loss
Total equity	$ 794,598	$ 797,643	$ 806,083	$ 818,299	$ 818,541	$ 823,324
Gross accounts receivable	55,700		48,600
Accounts receivable allowance	$ 12,200		12,700
Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
Allowance for Credit Loss
Total equity			$ 0