CONTRACT BALANCES (Schedule of Changes in Allowance for Doubtful Accounts) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 7,686	$ 8,685
Add: provision for doubtful accounts	15,933	4,264
Less: write-offs, net of recoveries	(9,031)	(5,501)
Balance, end of period	$ 14,588	$ 7,448