Summary of Significant Accounting Policies and Basis of Presentation (Detail) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($) ReportingUnit	Dec. 31, 2017 USD ($)
Basis Of Presentation And Accounting Policies [Line Items]
Number of reporting units having impairment indicators \| ReportingUnit		2
Goodwill impairment	$ 6,151	$ 6,151
Other intangible assets impairment	3,135	3,135
Accounts receivable, net of allowance for doubtful accounts	183,476	183,476	$ 185,058
Aggregate amount of transaction price allocated to material rights that remain unsatisfied	1,914	$ 1,914
Revenue expected to be recognized in next 3 months		17.00%
Revenue expected to be recognized in 2019		54.00%
Revenue expected to be recognized in 2020		16.00%
Revenue expected to be recognized in 2021		8.00%
Revenue expected to be recognized in 2022		3.00%
Revenue expected to be recognized in 2023		2.00%
Unearned revenue	6,128	$ 6,128	4,889
Minimum
Basis Of Presentation And Accounting Policies [Line Items]
Payment terms of contracts		30 days
Maximum
Basis Of Presentation And Accounting Policies [Line Items]
Payment terms of contracts		120 days
Industrial Segments
Basis Of Presentation And Accounting Policies [Line Items]
Unearned revenue	$ 4,214	$ 4,214	$ 4,889

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