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Receivables, Contract Liabilities and Performance Obligations - Additional Information (Detail) - USD ($)
9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]    
Contract with customer, liability, revenue recognized   $ 53,454,000
Description of expected duration With the exception of remaining performance obligations associated with our OneCall Support Services contracts which are included in the table above regardless of original duration, remaining performance obligations that have original expected durations of one year or less are not included in the table above.  Amounts not included in the table above have an average original expected duration of nine months.  
Time and material contracts expected duration 22 months