XML 74 R56.htm IDEA: XBRL DOCUMENT v3.21.2
Revenue - Summary of Accounts Receivable Billed and Unbilled and Deferred Revenue (Parenthetical) (Detail) - USD ($)
$ in Thousands
Sep. 30, 2021
Sep. 30, 2020
Revenue from Contract with Customer [Abstract]    
Allowance for doubtful accounts $ 20,065 $ 23,419