Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Summarized financial information for the Company's reportable segments
Rental Revenues	$ 60,601	$ 59,520
Rental Related Services Revenues	10,845	10,665
Sales and Other Revenues	17,267	8,744
Total Revenues	88,713	78,929
Depreciation of Rental Equipment	16,602	15,401
Gross Profit (Loss)	38,998	39,835
Selling and Administrative Expenses	21,638	21,361
Income (Loss) from Operations	17,360	18,474
Interest Expense (Income) Allocation	2,203	2,173
Income (Loss) before Provision for Income Taxes	15,157	16,301
Rental Equipment Acquisitions	27,442	39,535
Accounts Receivable, net (period end)	87,026	84,593	92,256
Rental Equipment, at cost (period end)	1,087,365	1,027,999	1,072,845
Rental Equipment, net book value (period end)	726,100	693,577	718,853
Mobile Modular [Member]
Summarized financial information for the Company's reportable segments
Rental Revenues	19,329	19,891
Rental Related Services Revenues	5,914	6,120
Sales and Other Revenues	3,748	2,344
Total Revenues	28,991	28,355
Depreciation of Rental Equipment	3,518	3,474
Gross Profit (Loss)	11,662	12,481
Selling and Administrative Expenses	8,800	8,487
Income (Loss) from Operations	2,862	3,994
Interest Expense (Income) Allocation	1,093	1,103
Income (Loss) before Provision for Income Taxes	1,769	2,891
Rental Equipment Acquisitions	8,490	4,251
Accounts Receivable, net (period end)	36,259	40,895
Rental Equipment, at cost (period end)	558,471	541,357
Rental Equipment, net book value (period end)	388,960	382,930
Utilization (period end)	66.10%	65.70%
Average Utilization	66.40%	66.50%
TRS-RenTelco [Member]
Summarized financial information for the Company's reportable segments
Rental Revenues	24,841	23,412
Rental Related Services Revenues	666	829
Sales and Other Revenues	7,207	6,256
Total Revenues	32,714	30,497
Depreciation of Rental Equipment	9,816	9,284
Gross Profit (Loss)	15,594	14,054
Selling and Administrative Expenses	6,094	6,696
Income (Loss) from Operations	9,500	7,358
Interest Expense (Income) Allocation	557	578
Income (Loss) before Provision for Income Taxes	8,943	6,780
Rental Equipment Acquisitions	12,198	12,915
Accounts Receivable, net (period end)	25,627	21,785
Rental Equipment, at cost (period end)	267,411	262,845
Rental Equipment, net book value (period end)	107,683	106,982
Utilization (period end)	63.30%	65.10%
Average Utilization	63.80%	65.50%
Adler Tanks [Member]
Summarized financial information for the Company's reportable segments
Rental Revenues	16,431	16,217
Rental Related Services Revenues	4,265	3,716
Sales and Other Revenues	119	137
Total Revenues	20,815	20,070
Depreciation of Rental Equipment	3,268	2,643
Gross Profit (Loss)	11,143	13,306
Selling and Administrative Expenses	5,992	5,097
Income (Loss) from Operations	5,151	8,209
Interest Expense (Income) Allocation	609	531
Income (Loss) before Provision for Income Taxes	4,542	7,678
Rental Equipment Acquisitions	6,754	22,369
Accounts Receivable, net (period end)	22,049	18,752
Rental Equipment, at cost (period end)	261,483	223,797
Rental Equipment, net book value (period end)	229,457	203,665
Utilization (period end)	63.50%	72.90%
Average Utilization	64.70%	76.50%
Enviroplex [Member]
Summarized financial information for the Company's reportable segments
Sales and Other Revenues	6,193	7
Total Revenues	6,193	7
Gross Profit (Loss)	599	(6)
Selling and Administrative Expenses	752	1,081
Income (Loss) from Operations	(153)	(1,087)
Interest Expense (Income) Allocation	(56)	(39)
Income (Loss) before Provision for Income Taxes	(97)	(1,048)
Accounts Receivable, net (period end)	$ 3,091	$ 3,161