Segment Reporting - Summarized Financial Information for Company's Reportable Segments (Detail) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Rental revenues		$ 70,694	$ 70,195	$ 67,305	$ 65,502	$ 71,694	$ 69,642	$ 65,809	$ 62,430	$ 273,696	$ 269,575	$ 255,766
Rental related services revenues										73,314	64,132	53,148
Sales and other revenues										57,534	74,415	70,595
Total revenues		105,282	113,048	96,026	90,188	111,792	113,025	95,745	87,560	404,544	408,122	379,509
Depreciation of rental equipment										75,213	72,678	68,208
Gross profit		46,756	50,146	40,918	39,087	52,204	49,298	42,079	38,638	176,907	182,219	169,015
Selling and administrative expenses										99,950	96,859	88,765
Income (loss) from operation		21,467	25,150	16,465	13,875	26,796	25,098	18,239	15,227	76,957	85,360	80,250
Interest expense (income) allocation										(10,092)	9,280	8,687
Income before provision for income taxes		18,523	22,505	14,033	11,316	24,222	22,609	16,794	12,936	66,377	76,561	71,374
Rental equipment acquisitions										133,378	148,602	136,601
Accounts receivable, net (period end)		95,263				101,294				95,263	101,294	87,650
Rental equipment, at cost (period end)		1,310,083				1,229,638				1,310,083	1,229,638	1,144,168
Rental equipment, net book value (period end)		869,601	$ 864,277	$ 856,489	$ 839,078	825,750	$ 817,898	$ 795,532	$ 775,875	869,601	825,750	767,010
Mobile Modular [Member]
Segment Reporting Information [Line Items]
Rental revenues										115,986	96,457	82,503
Rental related services revenues										45,616	35,263	28,891
Sales and other revenues										22,682	29,855	21,267
Total revenues										184,284	161,575	132,661
Depreciation of rental equipment										19,246	16,536	14,459
Gross profit										78,771	63,455	50,423
Selling and administrative expenses										46,496	42,069	36,488
Income (loss) from operation										32,275	21,386	13,935
Interest expense (income) allocation										(5,363)	4,768	4,318
Income before provision for income taxes										26,912	16,959	9,617
Rental equipment acquisitions										79,622	82,792	52,953
Accounts receivable, net (period end)		53,796				46,797				53,796	46,797	37,163
Rental equipment, at cost (period end)		736,875				664,340				736,875	664,340	592,391
Rental equipment, net book value (period end)		529,483				473,960				$ 529,483	$ 473,960	$ 415,366
Utilization (period end)	[1]									76.90%	75.00%	70.70%
Average utilization	[1]									75.80%	72.30%	68.30%
TRS-RenTelco [Member]
Segment Reporting Information [Line Items]
Rental revenues										$ 89,208	$ 99,020	$ 102,101
Rental related services revenues										3,055	3,331	3,095
Sales and other revenues										22,754	25,951	29,857
Total revenues										115,017	128,302	135,053
Depreciation of rental equipment										39,974	40,935	39,953
Gross profit										47,836	60,249	63,520
Selling and administrative expenses										22,930	23,736	24,542
Income (loss) from operation										24,906	36,513	38,978
Interest expense (income) allocation										(2,194)	2,075	2,156
Income before provision for income taxes										22,224	34,383	36,633
Rental equipment acquisitions										44,316	45,158	52,625
Accounts receivable, net (period end)		21,784				28,849				21,784	28,849	27,328
Rental equipment, at cost (period end)		262,945				261,995				262,945	261,995	267,772
Rental equipment, net book value (period end)		102,191				105,729				$ 102,191	$ 105,729	$ 109,988
Utilization (period end)	[1]									58.70%	59.80%	58.20%
Average utilization	[1]									60.50%	60.40%	62.70%
Adler Tanks [Member]
Segment Reporting Information [Line Items]
Rental revenues										$ 68,502	$ 74,098	$ 71,162
Rental related services revenues										24,643	25,538	21,162
Sales and other revenues										1,486	1,152	1,616
Total revenues										94,631	100,788	93,940
Depreciation of rental equipment										15,993	15,207	13,796
Gross profit										47,397	53,452	51,076
Selling and administrative expenses										27,494	27,424	24,644
Income (loss) from operation										19,903	26,028	26,432
Interest expense (income) allocation										(2,729)	2,618	2,419
Income before provision for income taxes										17,174	23,605	24,013
Rental equipment acquisitions										9,440	20,652	31,023
Accounts receivable, net (period end)		17,955				21,031				17,955	21,031	21,915
Rental equipment, at cost (period end)		310,263				303,303				310,263	303,303	284,005
Rental equipment, net book value (period end)		237,927				246,061				$ 237,927	$ 246,061	$ 241,656
Utilization (period end)	[1]									49.70%	63.90%	57.70%
Average utilization	[1]									58.30%	62.90%	64.20%
Enviroplex [Member]
Segment Reporting Information [Line Items]
Sales and other revenues	[2]									$ 10,612	$ 17,457	$ 17,855
Total revenues	[2]									10,612	17,457	17,855
Gross profit	[2]									2,903	5,063	3,996
Selling and administrative expenses	[2]									3,030	3,630	3,091
Income (loss) from operation	[2]									(127)	1,433	905
Interest expense (income) allocation	[2]									194	(181)	(206)
Income before provision for income taxes	[2]									67	1,614	1,111
Accounts receivable, net (period end)	[2]	$ 1,728				$ 4,617				$ 1,728	$ 4,617	$ 1,244

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

[2] Gross Enviroplex sales revenues were $11,530, $19,017 and $17,859 in 2015, 2014 and 2013, respectively, which includes inter-segment sales to Mobile Modular of $918, $1,560 and $4, which have been eliminated in consolidation.