ACCOUNTS RECEIVABLE - Schedule of Total Accounts Receivable (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Jun. 30, 2019
Accounts Receivable Net [Abstract]
Billed receivables	$ 555,472	$ 638,135
Billable receivables	223,867	141,632
Unbilled receivables	61,888	90,073
Total accounts receivable, current	841,227	869,840
Unbilled receivables, long-term	9,629	7,381
Total accounts receivable	$ 850,856	$ 877,221