Segment Reporting - Summarized Financial Information for Company's Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Rental Revenues	$ 66,181	$ 65,941	$ 63,043	$ 60,601	$ 65,117	$ 63,418	$ 60,389	$ 59,520	$ 255,766	$ 248,444	$ 234,906
Rental Related Services Revenues									53,148	46,920	39,486
Sales and Other Revenues									70,406	68,710	68,278
Total Revenues	94,614	108,860	87,133	88,713	101,950	99,430	83,765	78,929	379,320	364,074	342,670
Depreciation of Rental Equipment									68,208	63,819	60,187
Gross Profit	44,472	45,210	40,146	38,998	44,039	43,640	40,780	39,835	168,826	168,294	166,791
Interest Expense (Income) Allocation									8,687	9,149	7,606
Income (Loss) before Provision for Income Taxes	19,341	20,679	16,197	15,157	18,851	20,480	17,235	16,301	71,374	72,867	81,058
Rental Equipment Acquisitions									136,601	128,754	157,754
Accounts Receivable, net (period end)	87,650				92,256				87,650	92,256	92,671
Rental Equipment, at cost (period end)	1,144,168				1,072,845				1,144,168	1,072,845	999,189
Rental Equipment, net book value (period end)	767,010	753,810	737,636	726,100	718,853	719,636	710,918	693,577	767,010	718,853	673,146
Operating Segments [Member] | Mobile Modular [Member]
Segment Reporting Information [Line Items]
Rental Revenues									82,503	79,518	79,969
Rental Related Services Revenues									28,891	25,775	24,063
Sales and Other Revenues									21,267	14,474	20,577
Total Revenues									132,661	119,767	124,609
Depreciation of Rental Equipment									14,459	13,942	13,780
Gross Profit									50,423	52,022	55,193
Interest Expense (Income) Allocation									4,318	4,547	4,036
Income (Loss) before Provision for Income Taxes									9,617	13,443	19,026
Rental Equipment Acquisitions									52,953	21,042	33,824
Accounts Receivable, net (period end)	37,163				39,066				37,163	39,066	44,013
Rental Equipment, at cost (period end)	592,391				551,101				592,391	551,101	539,147
Rental Equipment, net book value (period end)	415,366				384,813				415,366	384,813	383,621
Utilization (period end)									70.70%	66.70%	67.30%
Average Utilization									68.30%	66.40%	67.10%
Operating Segments [Member] | TRS-RenTelco [Member]
Segment Reporting Information [Line Items]
Rental Revenues									102,101	101,645	95,694
Rental Related Services Revenues									3,095	3,673	3,133
Sales and Other Revenues									29,668	27,855	26,488
Total Revenues									134,864	133,173	125,315
Depreciation of Rental Equipment									39,953	38,174	38,039
Gross Profit									63,331	62,083	57,069
Interest Expense (Income) Allocation									2,156	2,384	2,124
Income (Loss) before Provision for Income Taxes									36,633	33,631	29,024
Rental Equipment Acquisitions									52,625	51,793	55,302
Accounts Receivable, net (period end)	27,328				24,654				27,328	24,654	24,236
Rental Equipment, at cost (period end)	267,772				266,934				267,772	266,934	258,586
Rental Equipment, net book value (period end)	109,988				107,999				109,988	107,999	105,565
Utilization (period end)									58.20%	64.10%	67.10%
Average Utilization									62.70%	65.80%	66.00%
Operating Segments [Member] | Adler Tanks [Member]
Segment Reporting Information [Line Items]
Rental Revenues									71,162	67,281	59,243
Rental Related Services Revenues									21,162	17,472	12,290
Sales and Other Revenues									1,616	2,558	425
Total Revenues									93,940	87,311	71,958
Depreciation of Rental Equipment									13,796	11,703	8,368
Gross Profit									51,076	51,157	49,619
Interest Expense (Income) Allocation									2,419	2,350	1,659
Income (Loss) before Provision for Income Taxes									24,013	26,706	31,262
Rental Equipment Acquisitions									31,023	55,919	68,628
Accounts Receivable, net (period end)	21,915				24,323				21,915	24,323	19,226
Rental Equipment, at cost (period end)	284,005				254,810				284,005	254,810	201,456
Rental Equipment, net book value (period end)	241,656				226,041				241,656	226,041	183,960
Utilization (period end)									57.70%	67.50%	79.80%
Average Utilization									64.20%	71.50%	86.20%
Operating Segments [Member] | Enviroplex [Member]
Segment Reporting Information [Line Items]
Rental Revenues
Rental Related Services Revenues
Sales and Other Revenues									17,855	23,823	20,788
Total Revenues									17,855	23,823	20,788
Depreciation of Rental Equipment
Gross Profit									3,996	3,032	4,910
Interest Expense (Income) Allocation									(206)	(132)	(213)
Income (Loss) before Provision for Income Taxes									1,111	(913)	1,746
Rental Equipment Acquisitions
Accounts Receivable, net (period end)	1,244				4,213				1,244	4,213	5,197
Rental Equipment, at cost (period end)
Rental Equipment, net book value (period end)