Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Summarized financial information for the Company's reportable segments
Rental Revenues	$ 60,389	$ 57,118	$ 119,909	$ 111,144
Rental Related Services Revenues	11,028	9,387	21,693	17,879
Sales and Other Revenues	11,830	12,489	19,936	22,423
Total Revenues	83,765	79,509	162,694	152,546
Depreciation of Rental Equipment	15,672	14,842	31,073	29,437
Gross Profit	40,780	39,338	80,615	75,254
Selling and Administrative Expenses	21,163	18,624	42,524	37,246
Income (Loss) from Operations	19,617	20,714	38,091	38,008
Interest Expense (Income) Allocation	2,382	1,954	4,555	3,436
Income (Loss) before Provision for Income Taxes	17,235	18,760	33,536	34,572
Rental Equipment Acquisitions			9,989	11,812
Accounts Receivable, net (period end)	86,402		86,402		92,671
Rental Equipment, at cost (period end)	1,053,017		1,053,017		999,189
Rental Equipment, net book value (period end)	710,918		710,918		673,146
Mobile Modular [Member]
Summarized financial information for the Company's reportable segments
Rental Revenues			39,413	39,566
Rental Related Services Revenues			12,200	11,321
Sales and Other Revenues			4,522	8,241
Total Revenues			56,135	59,128
Depreciation of Rental Equipment			6,959	6,849
Gross Profit			24,505	26,429
Selling and Administrative Expenses			16,779	15,599
Income (Loss) from Operations			7,726	10,830
Interest Expense (Income) Allocation			2,294	1,854
Income (Loss) before Provision for Income Taxes			5,432	8,976
Rental Equipment Acquisitions			11,702	18,910
Accounts Receivable, net (period end)	34,762	36,591	34,762	36,591
Rental Equipment, at cost (period end)	547,248	529,056	547,248	529,056
Rental Equipment, net book value (period end)	385,901	378,689	385,901	378,689
Utilization (period end)			65.60%	67.70%
Average Utilization			66.20%	67.20%
TRS-RenTelco [Member]
Summarized financial information for the Company's reportable segments
Rental Revenues			48,267	45,611
Rental Related Services Revenues			1,684	1,402
Sales and Other Revenues			11,151	13,162
Total Revenues			61,102	60,175
Depreciation of Rental Equipment			18,610	18,836
Gross Profit			28,842	27,044
Selling and Administrative Expenses			13,105	12,649
Income (Loss) from Operations			15,737	14,395
Interest Expense (Income) Allocation			1,198	972
Income (Loss) before Provision for Income Taxes			14,539	13,423
Rental Equipment Acquisitions			29,379	31,927
Accounts Receivable, net (period end)	23,120	21,711	23,120	21,711
Rental Equipment, at cost (period end)	270,747	260,563	270,747	260,563
Rental Equipment, net book value (period end)	112,922	106,970	112,922	106,970
Utilization (period end)			65.70%	65.40%
Average Utilization			65.90%	65.30%
Adler Tanks [Member]
Summarized financial information for the Company's reportable segments
Rental Revenues			32,229	25,967
Rental Related Services Revenues			7,809	5,156
Sales and Other Revenues			696	170
Total Revenues			40,734	31,293
Depreciation of Rental Equipment			5,504	3,752
Gross Profit			26,004	21,177
Selling and Administrative Expenses			10,409	7,317
Income (Loss) from Operations			15,595	13,860
Interest Expense (Income) Allocation			1,134	717
Income (Loss) before Provision for Income Taxes			14,461	13,143
Rental Equipment Acquisitions			34,041	26,745
Accounts Receivable, net (period end)	20,169	16,882	20,169	16,882
Rental Equipment, at cost (period end)	235,022	159,756	235,022	159,756
Rental Equipment, net book value (period end)	212,095	146,859	212,095	146,859
Utilization (period end)			67.50%	86.40%
Average Utilization			73.30%	85.40%
Enviroplex [Member]
Summarized financial information for the Company's reportable segments
Rental Revenues
Rental Related Services Revenues
Sales and Other Revenues			4,723	1,950
Total Revenues			4,723	1,950
Depreciation of Rental Equipment
Gross Profit			1,264	604
Selling and Administrative Expenses			2,231	1,681
Income (Loss) from Operations			(967)	(1,077)
Interest Expense (Income) Allocation			(71)	(107)
Income (Loss) before Provision for Income Taxes			(896)	(970)
Rental Equipment Acquisitions
Accounts Receivable, net (period end)	8,351	3,646	8,351	3,646
Rental Equipment, at cost (period end)
Rental Equipment, net book value (period end)
Consolidated [Member]
Summarized financial information for the Company's reportable segments
Rental Revenues			119,909	111,144
Rental Related Services Revenues			21,693	17,879
Sales and Other Revenues			21,092	23,523
Total Revenues			162,694	152,546
Depreciation of Rental Equipment			31,073	29,437
Gross Profit			80,615	75,254
Selling and Administrative Expenses			42,524	37,246
Income (Loss) from Operations			38,091	38,008
Interest Expense (Income) Allocation			4,555	3,436
Income (Loss) before Provision for Income Taxes			33,536	34,572
Rental Equipment Acquisitions			75,122	77,582
Accounts Receivable, net (period end)	86,402	78,830	86,402	78,830
Rental Equipment, at cost (period end)	1,053,017	949,375	1,053,017	949,375
Rental Equipment, net book value (period end)	$ 710,918	$ 632,518	$ 710,918	$ 632,518