CONTRACT BALANCES (Schedule of Changes in Allowance for Doubtful Accounts) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 7,686	$ 8,685
Add: provision for doubtful accounts	21,897	8,716
Less: write-offs, net of recoveries	(17,876)	(10,536)
Balance, end of period	$ 11,707	$ 6,865