Segment Reporting - Summarized Financial Information for Company's Reportable Segments (Parenthetical) (Detail) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenues		$ 143,147,000	$ 135,388,000	$ 365,215,000		$ 339,807,000
Sales revenues				(70,735,000)		(69,508,000)
Sales [Member]
Segment Reporting Information [Line Items]
Sales revenues		(36,085,000)	(38,684,000)	(67,722,000)		(67,166,000)
Enviroplex [Member]
Segment Reporting Information [Line Items]
Revenues		14,102,000	15,781,000	19,831,000	[1]	20,692,000	[1]
Sales revenues	[1]			(19,831,000)		(20,692,000)
Mobile Modular [Member]
Segment Reporting Information [Line Items]
Revenues		$ 74,891,000	$ 68,887,000	188,613,000		173,828,000
Sales revenues				(31,667,000)		(30,622,000)
Operating Segments [Member] | Enviroplex [Member] | Sales [Member]
Segment Reporting Information [Line Items]
Revenues				21,191,000		20,692,000
Inter-segment Eliminations [Member] | Sales [Member]
Segment Reporting Information [Line Items]
Sales revenues						$ 0
Inter-segment Eliminations [Member] | Mobile Modular [Member] | Sales [Member]
Segment Reporting Information [Line Items]
Sales revenues				$ 1,360,000

[1] Gross Enviroplex sales revenues were $21,191 and $20,692 for the nine months ended September 30, 2018 and 2017, respectively. There were $1,360 inter-segment sales to Mobile Modular in the nine months ended September 30, 2018, which required elimination in consolidation. There were no inter-segment sales in the nine months ended September 30, 2017.