Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017 USD ($) Division Segment shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($)	Aug. 31, 2015 shares	May 31, 2008 shares
Summary Of Significant Accounting Policies [Line Items]
Number of divisions | Division	4
Number of reportable segments | Segment	4
Impairments of long-lived assets	$ 1,639,000	$ 0	$ 0
Period for warranties for rental equipment	90 days
Period for warranties for equipment manufactured	1 year
Property, plant and equipment depreciation expenses	$ 7,600,000	8,100,000	8,200,000
Capitalized in internal use of software	800,000	200,000
Total advertising expenses	$ 2,900,000	2,900,000	2,800,000
Estimated useful life in years, Customer relationships	11 years
Goodwill and trade name intangible assets	$ 33,500,000	33,500,000
Goodwill and intangible assets impairment charge	$ 0	$ 0	0
Common stock shares authorized for repurchase | shares				2,000,000	2,000,000
Common stock repurchased | shares	0	0
Shares remain authorized for repurchase | shares	1,592,026
Unbilled receivables related to end-of-lease services	$ 30,100,000	$ 28,100,000
Period for credit risk identified	30 days
Estimated fair value notes payable	$ 120,200,000	140,700,000
Recorded fair value of notes payable	120,000,000	140,000,000
Prior period reclassification adjustment		2,700,000	$ 2,400,000
ASU 2016-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Excess tax benefits related to share-based payments	869,000
Decrease in net cash provided by operations and net cash used in financing activities due to retrospective application of new accounting standard		$ 1,066,000
Modular Rental Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Impairments of long-lived assets	$ 1,600,000