Segment Reporting - Summarized Financial Information for Company's Reportable Segments (Parenthetical) (Detail) - USD ($)		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues		$ 147,221,000	$ 173,562,000	$ 127,439,000	$ 122,008,000	$ 133,115,000	$ 143,147,000	$ 116,983,000	$ 105,085,000	$ 570,230,000	$ 498,330,000	$ 462,034,000
Sales revenues										(115,303,000)	(96,649,000)	(94,549,000)
Sales [Member]
Segment Reporting Information [Line Items]
Sales revenues										(110,229,000)	(92,618,000)	(91,500,000)
Enviroplex [Member]
Segment Reporting Information [Line Items]
Revenues	[1]									39,814,000	29,046,000	31,369,000
Sales revenues	[1]									(39,814,000)	(29,046,000)	(31,369,000)
Mobile Modular [Member]
Segment Reporting Information [Line Items]
Revenues										301,010,000	254,574,000	231,266,000
Sales revenues										(49,299,000)	(40,742,000)	(38,234,000)
Operating Segments [Member] | Enviroplex [Member] | Sales [Member]
Segment Reporting Information [Line Items]
Revenues										39,814,000	30,407,000	31,369,000
Inter-segment Eliminations [Member]
Segment Reporting Information [Line Items]
Sales revenues										$ 0		$ 0
Type of Revenue [Extensible List]										us-gaap:ProductMember		us-gaap:ProductMember
Inter-segment Eliminations [Member] | Mobile Modular [Member]
Segment Reporting Information [Line Items]
Sales revenues											$ 1,361,000
Type of Revenue [Extensible List]											us-gaap:ProductMember

[1] Gross Enviroplex sales revenues were $39,814, $30,407 and $31,369 in 2019, 2018 and 2017, respectively.  There were $1,361 inter-segment sales to Mobile Modular in 2018, which have been eliminated in consolidation.  There were no inter-segment sales in 2019 and 2017.