Segment Reporting - Summarized Financial Information for Company's Reportable Segments (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Rental revenues		$ 67,757	$ 70,195	$ 201,036	$ 203,002
Rental related services revenues		20,122	21,862	57,028	54,456
Sales and other revenues				60,733	41,804
Total revenues		121,993	113,048	318,797	299,262
Depreciation of rental equipment		17,819	18,809	54,590	56,507
Gross profit		50,433	50,146	134,844	130,151
Selling and administrative expenses		26,201	24,996	78,281	74,661
Income (loss) from operations		24,232	25,150	56,563	55,490
Interest (expense) income allocation				(9,486)	(7,182)
Income (loss) before provision for income taxes		21,277	22,505	47,136	47,854
Rental equipment acquisitions				60,758	105,651
Accounts receivable, net (period end)		104,004	107,560	104,004	107,560	$ 95,263
Rental equipment, at cost (period end)		1,325,202	1,293,705	1,325,202	1,293,705	1,310,083
Rental equipment, net book value (period end)		862,528	864,277	862,528	864,277	$ 869,601
Mobile Modular [Member]
Segment Reporting Information [Line Items]
Rental revenues				96,002	84,242
Rental related services revenues				37,034	33,904
Sales and other revenues				25,416	15,971
Total revenues				158,452	134,117
Depreciation of rental equipment				15,642	14,218
Gross profit				67,329	56,263
Selling and administrative expenses				38,162	34,436
Income (loss) from operations				29,167	21,827
Interest (expense) income allocation				(5,264)	(3,790)
Income (loss) before provision for income taxes				23,903	18,037
Rental equipment acquisitions				35,363	59,501
Accounts receivable, net (period end)		63,752	60,132	63,752	60,132
Rental equipment, at cost (period end)		763,777	717,892	763,777	717,892
Rental equipment, net book value (period end)		543,141	515,207	$ 543,141	$ 515,207
Utilization (period end)	[1]			77.60%	77.90%
Average utilization	[1]			76.30%	75.30%
TRS-RenTelco [Member]
Segment Reporting Information [Line Items]
Rental revenues				$ 61,562	$ 66,612
Rental related services revenues				2,156	2,271
Sales and other revenues				18,491	16,385
Total revenues				82,209	85,268
Depreciation of rental equipment				26,939	30,335
Gross profit				34,033	35,293
Selling and administrative expenses				16,444	17,059
Income (loss) from operations				17,589	18,234
Interest (expense) income allocation				(1,921)	(1,580)
Income (loss) before provision for income taxes				15,727	16,200
Rental equipment acquisitions				24,991	37,822
Accounts receivable, net (period end)		20,267	23,649	20,267	23,649
Rental equipment, at cost (period end)		252,573	266,034	252,573	266,034
Rental equipment, net book value (period end)		93,894	107,801	$ 93,894	$ 107,801
Utilization (period end)	[1]			62.40%	60.50%
Average utilization	[1]			60.10%	60.20%
Adler Tanks [Member]
Segment Reporting Information [Line Items]
Rental revenues				$ 43,472	$ 52,148
Rental related services revenues				17,838	18,281
Sales and other revenues				1,039	1,082
Total revenues				62,349	71,511
Depreciation of rental equipment				12,009	11,954
Gross profit				28,362	36,383
Selling and administrative expenses				20,786	20,755
Income (loss) from operations				7,576	15,628
Interest (expense) income allocation				(2,487)	(1,953)
Income (loss) before provision for income taxes				5,089	13,675
Rental equipment acquisitions				404	8,328
Accounts receivable, net (period end)		15,922	20,312	15,922	20,312
Rental equipment, at cost (period end)		308,852	309,779	308,852	309,779
Rental equipment, net book value (period end)		225,493	241,269	$ 225,493	$ 241,269
Utilization (period end)	[1]			52.10%	57.00%
Average utilization	[1]			49.90%	59.90%
Enviroplex [Member]
Segment Reporting Information [Line Items]
Sales and other revenues	[2]			$ 15,787	$ 8,366
Total revenues	[2]			15,787	8,366
Gross profit	[2]			5,120	2,212
Selling and administrative expenses	[2]			2,889	2,411
Income (loss) from operations	[2]			2,231	(199)
Interest (expense) income allocation	[2]			186	141
Income (loss) before provision for income taxes	[2]			2,417	(58)
Accounts receivable, net (period end)	[2]	$ 4,063	$ 3,467	$ 4,063	$ 3,467

[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 $15,872 and $9,077 for the nine months ended September 30, 2016 and 2015, respectively, which include inter-segment sales to Mobile Modular of $85 and $711, respectively, which have been eliminated in consolidation.