Segment Reporting - Summarized Financial Information for Company's Reportable Segments (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Rental revenues		$ 86,087	$ 89,506
Rental related services revenues		19,669	24,511
Sales and other revenues		15,439	15,436
Total revenues		121,195	129,453
Depreciation of rental equipment		21,255	21,638
Gross profit		57,081	61,656
Selling and administrative expenses		33,137	31,954
Income from operations		23,944	29,702
Interest (expense) income allocation		(1,783)	(2,652)
Income (loss) before provision for income taxes		22,106	26,614
Rental equipment acquisitions		24,706	35,415
Accounts receivable, net (period end)		122,208	125,834	$ 123,316
Rental equipment, at cost (period end)		1,542,848	1,540,498	1,530,841
Rental equipment, net book value (period end)		935,943	975,709	$ 938,116
Mobile Modular [Member]
Segment Reporting Information [Line Items]
Rental revenues		46,657	47,410
Rental related services revenues		14,051	18,144
Sales and other revenues		7,940	7,644
Total revenues		68,648	73,198
Depreciation of rental equipment		5,819	5,669
Gross profit		34,934	36,859
Selling and administrative expenses		19,237	17,418
Income from operations		15,697	19,441
Interest (expense) income allocation		(1,046)	(1,547)
Income (loss) before provision for income taxes		14,651	17,894
Rental equipment acquisitions		8,428	19,135
Accounts receivable, net (period end)		81,378	79,220
Rental equipment, at cost (period end)		886,299	883,076
Rental equipment, net book value (period end)		$ 611,097	$ 620,138
Utilization (period end)	[1]	75.80%	78.30%
Average utilization	[1]	75.80%	78.70%
TRS-RenTelco [Member]
Segment Reporting Information [Line Items]
Rental revenues		$ 27,276	$ 27,536
Rental related services revenues		740	826
Sales and other revenues		5,587	5,701
Total revenues		33,603	34,063
Depreciation of rental equipment		11,362	11,832
Gross profit		14,753	14,757
Selling and administrative expenses		6,298	6,361
Income from operations		8,455	8,396
Interest (expense) income allocation		(420)	(647)
Income (loss) before provision for income taxes		7,980	7,313
Rental equipment acquisitions		16,380	16,075
Accounts receivable, net (period end)		21,367	23,949
Rental equipment, at cost (period end)		342,105	341,841
Rental equipment, net book value (period end)		$ 159,410	$ 174,762
Utilization (period end)	[1]	69.20%	63.80%
Average utilization	[1]	68.10%	65.30%
Adler Tanks [Member]
Segment Reporting Information [Line Items]
Rental revenues		$ 12,154	$ 14,560
Rental related services revenues		4,878	5,541
Sales and other revenues		678	588
Total revenues		17,710	20,689
Depreciation of rental equipment		4,074	4,137
Gross profit		7,043	9,509
Selling and administrative expenses		6,267	6,824
Income from operations		776	2,685
Interest (expense) income allocation		(431)	(661)
Income (loss) before provision for income taxes		345	2,024
Rental equipment acquisitions		(102)	205
Accounts receivable, net (period end)		13,030	15,967
Rental equipment, at cost (period end)		314,444	315,581
Rental equipment, net book value (period end)		$ 165,436	$ 180,809
Utilization (period end)	[1]	43.00%	47.00%
Average utilization	[1]	40.30%	47.80%
Enviroplex [Member]
Segment Reporting Information [Line Items]
Sales and other revenues	[2]	$ 1,234	$ 1,503
Total revenues	[2]	1,234	1,503
Gross profit	[2]	351	531
Selling and administrative expenses	[2]	1,335	1,351
Income from operations	[2]	(984)	(820)
Interest (expense) income allocation	[2]	114	203
Income (loss) before provision for income taxes	[2]	(870)	(617)
Accounts receivable, net (period end)	[2]	$ 6,433	$ 6,698

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

[2] Gross Enviroplex sales revenues were $2,090 and $2,778 for the three months ended March 31, 2021 and 2020, respectively. There were $856 and $1,275 inter-segment sales to Mobile Modular in the three months ended March 31, 2021 and 2020, respectively, which required elimination in consolidation.