Segment Reporting - Summarized Financial Information for Company's Reportable Segments (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Rental revenues		$ 70,195	$ 69,642	$ 203,002	$ 197,881
Rental related services revenues		21,862	17,871	54,456	46,529
Sales and other revenues				41,804	51,920
Total revenues		113,048	113,025	299,262	296,330
Depreciation of rental equipment		18,809	18,298	56,507	54,119
Gross profit		50,146	49,298	130,151	130,015
Selling and administrative expenses		24,996	24,200	74,661	71,451
Income (loss) from operations		25,150	25,098	55,490	58,564
Interest (expense) income allocation				(7,182)	6,924
Gain on sale of property, plant and equipment					812
Income (loss) before provision for income taxes		22,505	22,609	47,854	52,339
Rental equipment acquisitions				105,651	117,091
Accounts receivable, net (period end)		107,560	103,570	107,560	103,570	$ 101,294
Rental equipment, at cost (period end)		1,293,705	1,215,086	1,293,705	1,215,086	1,229,638
Rental equipment, net book value (period end)		864,277	817,898	864,277	817,898	$ 825,750
Mobile Modular [Member]
Segment Reporting Information [Line Items]
Rental revenues				84,242	69,644
Rental related services revenues				33,904	25,493
Sales and other revenues				15,971	22,057
Total revenues				134,117	117,194
Depreciation of rental equipment				14,218	12,114
Gross profit				56,263	43,296
Selling and administrative expenses				34,436	30,786
Income (loss) from operations				21,827	12,510
Interest (expense) income allocation				(3,790)	3,524
Gain on sale of property, plant and equipment					341
Income (loss) before provision for income taxes				18,037	9,327
Rental equipment acquisitions				59,501	65,100
Accounts receivable, net (period end)		60,132	55,525	60,132	55,525
Rental equipment, at cost (period end)		717,892	649,206	717,892	649,206
Rental equipment, net book value (period end)		515,207	462,722	$ 515,207	$ 462,722
Utilization (period end)	[1]			77.90%	74.20%
Average utilization	[1]			75.30%	71.40%
TRS-RenTelco [Member]
Segment Reporting Information [Line Items]
Rental revenues				$ 66,612	$ 73,665
Rental related services revenues				2,271	2,463
Sales and other revenues				16,385	18,369
Total revenues				85,268	94,497
Depreciation of rental equipment				30,335	30,709
Gross profit				35,293	43,916
Selling and administrative expenses				17,059	17,848
Income (loss) from operations				18,234	26,068
Interest (expense) income allocation				(1,580)	1,584
Gain on sale of property, plant and equipment					276
Income (loss) before provision for income taxes				16,200	24,647
Rental equipment acquisitions				37,822	32,903
Accounts receivable, net (period end)		23,649	22,228	23,649	22,228
Rental equipment, at cost (period end)		266,034	263,712	266,034	263,712
Rental equipment, net book value (period end)		107,801	106,460	$ 107,801	$ 106,460
Utilization (period end)	[1]			60.50%	64.20%
Average utilization	[1]			60.20%	59.60%
Adler Tanks [Member]
Segment Reporting Information [Line Items]
Rental revenues				$ 52,148	$ 54,572
Rental related services revenues				18,281	18,573
Sales and other revenues				1,082	893
Total revenues				71,511	74,038
Depreciation of rental equipment				11,954	11,296
Gross profit				36,383	39,779
Selling and administrative expenses				20,755	20,338
Income (loss) from operations				15,628	19,441
Interest (expense) income allocation				(1,953)	1,950
Gain on sale of property, plant and equipment					195
Income (loss) before provision for income taxes				13,675	17,686
Rental equipment acquisitions				8,328	19,088
Accounts receivable, net (period end)		20,312	21,190	20,312	21,190
Rental equipment, at cost (period end)		309,779	302,168	309,779	302,168
Rental equipment, net book value (period end)		241,269	248,716	$ 241,269	$ 248,716
Utilization (period end)	[1]			57.00%	65.10%
Average utilization	[1]			59.90%	62.20%
Enviroplex [Member]
Segment Reporting Information [Line Items]
Sales and other revenues	[2]			$ 8,366	$ 10,601
Total revenues	[2]			8,366	10,601
Gross profit	[2]			2,212	3,024
Selling and administrative expenses	[2]			2,411	2,479
Income (loss) from operations	[2]			(199)	545
Interest (expense) income allocation	[2]			141	(134)
Income (loss) before provision for income taxes	[2]			(58)	679
Accounts receivable, net (period end)	[2]	$ 3,467	$ 4,627	$ 3,467	$ 4,627

[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 $9,077 and $12,133 for the nine months ended September 30, 2015 and 2014, respectively, which includes inter-segment sales to Mobile Modular of $711 and $1,532, respectively, which have been eliminated in consolidation.