Segment Reporting - Summarized Financial Information for Company's Reportable Segments (Parenthetical) (Detail) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues		$ 122,227	$ 135,388	$ 109,582	$ 94,837	$ 105,283	$ 121,993	$ 103,105	$ 93,699	$ 462,034	$ 424,080	$ 404,544
Enviroplex [Member]
Segment Reporting Information [Line Items]
Revenues	[1]									31,369	22,121	10,612
Mobile Modular [Member]
Segment Reporting Information [Line Items]
Revenues										231,266	209,512	184,284
Operating Segments [Member] | Enviroplex [Member]
Segment Reporting Information [Line Items]
Revenues										31,369	22,206	11,530
Inter-segment Eliminations [Member] | Mobile Modular [Member]
Segment Reporting Information [Line Items]
Sales revenues										$ 0	$ 85	$ 918

[1] Gross Enviroplex sales revenues were $31,369, $22,206 and $11,530 in 2017, 2016 and 2015, respectively, which includes inter-segment sales to Mobile Modular of $0, $85 and $918, which have been eliminated in consolidation.