Segment Reporting - Summarized Financial Information for Company's Reportable Segments (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019		Dec. 31, 2019
Segment Reporting Information [Line Items]
Rental revenues		$ 88,138	$ 90,857	$ 263,273		$ 261,658
Rental related services revenues		25,040	30,816	70,026		76,738
Sales and other revenues				90,275		84,613
Total revenues		156,448	173,562	423,574		423,009
Depreciation of rental equipment		21,419	20,535	64,640		59,222
Gross profit		68,204	78,282	193,093		195,168
Selling and administrative expenses		30,871	31,534	93,365		92,044
Income from operations		37,333	46,748	99,728		103,124
Interest (expense) income allocation				(6,804)		(9,407)
Income before provision for income taxes		35,495	43,455	92,735		93,671
Rental equipment acquisitions				64,990		132,493
Accounts receivable, net (period end)		129,433	138,114	129,433		138,114		$ 128,099
Rental equipment, at cost (period end)		1,536,944	1,502,769	1,536,944		1,502,769		1,520,411
Rental equipment, net book value (period end)		948,125	958,610	948,125		958,610		$ 967,500
Mobile Modular [Member]
Segment Reporting Information [Line Items]
Rental revenues				141,172		133,736
Rental related services revenues				51,291		52,946
Sales and other revenues				52,910		32,434
Total revenues		95,413	86,302	245,373		219,116
Depreciation of rental equipment				17,177		16,449
Gross profit				116,928		102,029
Selling and administrative expenses				52,014		48,013
Income from operations				64,914		54,016
Interest (expense) income allocation				(3,982)		(5,948)
Income before provision for income taxes				60,932		48,068
Rental equipment acquisitions				31,667		62,084
Accounts receivable, net (period end)		85,033	88,893	85,033		88,893
Rental equipment, at cost (period end)		885,314	865,254	885,314		865,254
Rental equipment, net book value (period end)		613,357	607,949	$ 613,357		$ 607,949
Utilization (period end)	[1]			76.50%		79.50%
Average utilization	[1]			77.50%		79.10%
TRS-RenTelco [Member]
Segment Reporting Information [Line Items]
Rental revenues				$ 81,167		$ 76,050
Rental related services revenues				2,296		2,425
Sales and other revenues				19,535		18,601
Total revenues		35,856	34,090	102,998		97,076
Depreciation of rental equipment				35,129		30,533
Gross profit				43,921		44,673
Selling and administrative expenses				18,198		18,101
Income from operations				25,723		26,572
Interest (expense) income allocation				(1,606)		(1,662)
Income before provision for income taxes				23,928		24,864
Rental equipment acquisitions				31,643		66,525
Accounts receivable, net (period end)		23,758	22,515	23,758		22,515
Rental equipment, at cost (period end)		335,520	321,677	335,520		321,677
Rental equipment, net book value (period end)		161,120	162,196	$ 161,120		$ 162,196
Utilization (period end)	[1]			68.40%		67.10%
Average utilization	[1]			65.60%		66.00%
Adler Tanks [Member]
Segment Reporting Information [Line Items]
Rental revenues				$ 40,934		$ 51,872
Rental related services revenues				16,439		21,367
Sales and other revenues				1,214		1,340
Total revenues		19,265	24,809	58,587		74,579
Depreciation of rental equipment				12,334		12,240
Gross profit				26,116		36,380
Selling and administrative expenses				18,998		22,054
Income from operations				7,118		14,326
Interest (expense) income allocation				(1,651)		(2,598)
Income before provision for income taxes				5,467		11,728
Rental equipment acquisitions				1,680		3,884
Accounts receivable, net (period end)		14,567	19,382	14,567		19,382
Rental equipment, at cost (period end)		316,110	315,838	316,110		315,838
Rental equipment, net book value (period end)		173,648	188,465	$ 173,648		$ 188,465
Utilization (period end)	[1]			45.50%		51.00%
Average utilization	[1]			45.50%		56.20%
Enviroplex [Member]
Segment Reporting Information [Line Items]
Sales and other revenues	[2]			$ 16,616		$ 32,238
Total revenues		5,914	28,361	16,616	[2]	32,238	[2]
Gross profit	[2]			6,128		12,086
Selling and administrative expenses	[2]			4,155		3,876
Income from operations	[2]			1,973		8,210
Interest (expense) income allocation	[2]			435		801
Income before provision for income taxes	[2]			2,408		9,011
Accounts receivable, net (period end)	[2]	$ 6,075	$ 7,324	$ 6,075		$ 7,324

[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 $17,893 and $32,237 for the nine months ended September 30, 2020 and 2019, respectively. There were $1,277 inter-segment sales to Mobile Modular in the nine months ended September 30, 2020, which required elimination in consolidation.  There were no inter-segment sales in the nine months ended September 30, 2019.