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Implemented Accounting Pronouncements - Additional Information (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2018
Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]    
Period for credit risk identified 30 days  
Sales revenues totaling $ 2.3  
Period for warranties for rental equipment 90 days  
Period for warranties for equipment manufactured 1 year  
Deferred Income [Member]    
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]    
Customer contract liability $ 10.6 $ 6.8
Accounts Receivable [Member]    
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]    
Unbilled contract assets $ 1.3 $ 2.0