Implemented Accounting Pronouncements - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Period for credit risk identified		30 days
Sales revenues totaling	$ 2.1	$ 5.6
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	11.0	$ 11.0	$ 6.8
Accounts Receivable [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Unbilled contract assets	$ 0.3	$ 0.3	$ 2.0