Accounts Receivable - Schedule of Total Accounts Receivable (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Jun. 30, 2020
Accounts Receivable Net [Abstract]
Billed and billable receivables	$ 750,529	$ 779,339
Unbilled receivables	110,191	61,888
Total accounts receivable, net – current	860,720	841,227
Unbilled receivables, long-term	11,802	9,629
Total accounts receivable	$ 872,522	$ 850,856