Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Summarized financial information for the Company's reportable segments
Rental Revenues	$ 63,043	$ 60,389	$ 123,644	$ 119,909
Rental Related Services Revenues	12,661	11,028	23,506	21,693
Sales and Other Revenues			28,696	21,092
Total Revenues	87,133	83,765	175,846	162,694
Depreciation of Rental Equipment	16,626	15,672	33,228	31,073
Gross Profit	40,146	40,780	79,144	80,615
Selling and Administrative Expenses	21,792	21,163	43,430	42,524
Income (Loss) from Operations	18,354	19,617	35,714	38,091
Interest Expense (Income) Allocation			4,360	4,555
Income (Loss) before Provision for Income Taxes	16,197	17,235	31,354	33,536
Rental Equipment Acquisitions			60,029	75,122
Accounts Receivable, net (period end)	87,286	86,402	87,286	86,402	92,256
Rental Equipment, at cost (period end)	1,104,218	1,053,017	1,104,218	1,053,017	1,072,845
Rental Equipment, net book value (period end)	737,636	710,918	737,636	710,918	718,853
Mobile Modular [Member]
Summarized financial information for the Company's reportable segments
Rental Revenues			39,288	39,413
Rental Related Services Revenues			12,491	12,200
Sales and Other Revenues			6,715	4,522
Total Revenues			58,494	56,135
Depreciation of Rental Equipment			7,089	6,959
Gross Profit			22,894	24,505
Selling and Administrative Expenses			17,371	16,779
Income (Loss) from Operations			5,523	7,726
Interest Expense (Income) Allocation			2,158	2,294
Income (Loss) before Provision for Income Taxes			3,365	5,432
Rental Equipment Acquisitions			21,521	11,702
Accounts Receivable, net (period end)	37,573	34,762	37,573	34,762
Rental Equipment, at cost (period end)	570,352	547,248	570,352	547,248
Rental Equipment, net book value (period end)	397,702	385,901	397,702	385,901
Utilization (period end)			67.60%	65.60%
Average Utilization			66.70%	66.20%
TRS-RenTelco [Member]
Summarized financial information for the Company's reportable segments
Rental Revenues			50,179	48,267
Rental Related Services Revenues			1,412	1,684
Sales and Other Revenues			14,200	11,151
Total Revenues			65,791	61,102
Depreciation of Rental Equipment			19,474	18,610
Gross Profit			30,958	28,842
Selling and Administrative Expenses			12,400	13,105
Income (Loss) from Operations			18,558	15,737
Interest Expense (Income) Allocation			1,089	1,198
Income (Loss) before Provision for Income Taxes			17,469	14,539
Rental Equipment Acquisitions			22,655	29,379
Accounts Receivable, net (period end)	22,750	23,120	22,750	23,120
Rental Equipment, at cost (period end)	264,429	270,747	264,429	270,747
Rental Equipment, net book value (period end)	105,869	112,922	105,869	112,922
Utilization (period end)			63.30%	65.70%
Average Utilization			63.70%	65.90%
Adler Tanks [Member]
Summarized financial information for the Company's reportable segments
Rental Revenues			34,177	32,229
Rental Related Services Revenues			9,603	7,809
Sales and Other Revenues			1,354	696
Total Revenues			45,134	40,734
Depreciation of Rental Equipment			6,665	5,504
Gross Profit			24,557	26,004
Selling and Administrative Expenses			12,097	10,409
Income (Loss) from Operations			12,460	15,595
Interest Expense (Income) Allocation			1,213	1,134
Income (Loss) before Provision for Income Taxes			11,247	14,461
Rental Equipment Acquisitions			15,853	34,041
Accounts Receivable, net (period end)	24,139	20,169	24,139	20,169
Rental Equipment, at cost (period end)	269,437	235,022	269,437	235,022
Rental Equipment, net book value (period end)	234,065	212,095	234,065	212,095
Utilization (period end)			68.70%	67.50%
Average Utilization			65.50%	73.30%
Enviroplex [Member]
Summarized financial information for the Company's reportable segments
Sales and Other Revenues			6,427	4,723
Total Revenues			6,427	4,723
Gross Profit			735	1,264
Selling and Administrative Expenses			1,562	2,231
Income (Loss) from Operations			(827)	(967)
Interest Expense (Income) Allocation			(100)	(71)
Income (Loss) before Provision for Income Taxes			(727)	(896)
Accounts Receivable, net (period end)	$ 2,824	$ 8,351	$ 2,824	$ 8,351