Segment Reporting - Summarized Financial Information for Company's Reportable Segments (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Rental revenues		$ 67,978	$ 66,532
Rental related services revenues		17,935	17,591
Sales and other revenues		8,924	9,576
Total revenues		94,837	93,699
Depreciation of rental equipment		17,379	18,540
Gross profit		43,670	40,655
Selling and administrative expenses		27,848	26,397
Income (loss) from operations		15,822	14,258
Interest (expense) income allocation		(2,789)	(3,556)
Income (loss) before provision for income taxes		13,259	10,853
Rental equipment acquisitions		20,552	19,290
Accounts receivable, net (period end)		92,552	91,883	$ 96,877
Rental equipment, at cost (period end)		1,331,019	1,317,622	1,324,057
Rental equipment, net book value (period end)		856,981	867,215	$ 856,371
Mobile Modular [Member]
Segment Reporting Information [Line Items]
Rental revenues		33,654	31,155
Rental related services revenues		11,588	11,205
Sales and other revenues		3,061	2,724
Total revenues		48,303	45,084
Depreciation of rental equipment		5,333	5,126
Gross profit		22,444	20,653
Selling and administrative expenses		13,800	12,462
Income (loss) from operations		8,644	8,191
Interest (expense) income allocation		(1,591)	(1,947)
Income (loss) before provision for income taxes		7,053	6,244
Rental equipment acquisitions		7,782	11,579
Accounts receivable, net (period end)		53,779	50,915
Rental equipment, at cost (period end)		773,597	747,475
Rental equipment, net book value (period end)		$ 545,953	$ 535,308
Utilization (period end)	[1]	76.50%	75.40%
Average utilization	[1]	76.80%	76.10%
TRS-RenTelco [Member]
Segment Reporting Information [Line Items]
Rental revenues		$ 19,746	$ 20,928
Rental related services revenues		658	784
Sales and other revenues		4,910	6,272
Total revenues		25,314	27,984
Depreciation of rental equipment		8,091	9,388
Gross profit		11,393	11,016
Selling and administrative expenses		5,689	5,797
Income (loss) from operations		5,704	5,219
Interest (expense) income allocation		(546)	(730)
Income (loss) before provision for income taxes		5,384	4,640
Rental equipment acquisitions		12,021	7,729
Accounts receivable, net (period end)		18,603	21,393
Rental equipment, at cost (period end)		248,291	260,324
Rental equipment, net book value (period end)		$ 92,561	$ 98,291
Utilization (period end)	[1]	62.10%	59.90%
Average utilization	[1]	62.20%	59.60%
Adler Tanks [Member]
Segment Reporting Information [Line Items]
Rental revenues		$ 14,578	$ 14,449
Rental related services revenues		5,689	5,602
Sales and other revenues		194	432
Total revenues		20,461	20,483
Depreciation of rental equipment		3,955	4,026
Gross profit		9,555	8,942
Selling and administrative expenses		7,267	7,262
Income (loss) from operations		2,288	1,680
Interest (expense) income allocation		(738)	(934)
Income (loss) before provision for income taxes		1,550	746
Rental equipment acquisitions		749	(18)
Accounts receivable, net (period end)		15,814	15,386
Rental equipment, at cost (period end)		309,131	309,823
Rental equipment, net book value (period end)		$ 218,467	$ 233,616
Utilization (period end)	[1]	53.40%	51.00%
Average utilization	[1]	52.30%	50.30%
Enviroplex [Member]
Segment Reporting Information [Line Items]
Sales and other revenues	[2]	$ 759	$ 148
Total revenues	[2]	759	148
Gross profit	[2]	278	44
Selling and administrative expenses	[2]	1,092	876
Income (loss) from operations	[2]	(814)	(832)
Interest (expense) income allocation	[2]	86	55
Income (loss) before provision for income taxes	[2]	(728)	(777)
Accounts receivable, net (period end)	[2]	$ 4,356	$ 4,189

[1] Utilization is calculated each month by dividing the cost of rental equipment on rent by the total cost of rental equipment excluding accessory equipment and for Mobile Modular and Adler Tanks excluding new equipment inventory. The Average Utilization for the period is calculated using the average costs of rental equipment.

[2] Gross Enviroplex sales revenues were $759 and $148 for the three months ended March 31, 2017 and 2016, respectively. There were no inter-segment sales to Mobile Modular in those periods requiring elimination in consolidation.