Segment Reporting - Summarized Financial Information for Company's Reportable Segments (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020		Jun. 30, 2019		Dec. 31, 2019
Segment Reporting Information [Line Items]
Rental revenues		$ 85,629	$ 88,105	$ 175,135		$ 170,801
Rental related services revenues		20,475	24,467	44,986		45,922
Sales and other revenues				47,005		32,724
Total revenues		137,673	127,439	267,126		249,447
Depreciation of rental equipment		21,583	19,726	43,221		38,687
Gross profit		63,232	59,881	124,888		116,886
Selling and administrative expenses		30,540	30,815	62,494		60,510
Income from operations		32,692	29,066	62,394		56,376
Interest (expense) income allocation				(4,836)		(6,246)
Income (loss) before provision for income taxes		30,625	25,965	57,239		50,216
Rental equipment acquisitions				57,721		89,940
Accounts receivable, net (period end)		125,940	121,018	125,940		121,018		$ 128,099
Rental equipment, at cost (period end)		1,546,823	1,477,286	1,546,823		1,477,286		1,520,411
Rental equipment, net book value (period end)		969,681	943,152	969,681		943,152		$ 967,500
Mobile Modular [Member]
Segment Reporting Information [Line Items]
Rental revenues				94,038		86,998
Rental related services revenues				32,607		30,372
Sales and other revenues				23,315		15,444
Total revenues		76,762	67,722	149,960		132,814
Depreciation of rental equipment				11,406		10,877
Gross profit				74,301		62,865
Selling and administrative expenses				34,275		31,047
Income from operations				40,026		31,818
Interest (expense) income allocation				(2,826)		(3,761)
Income (loss) before provision for income taxes				37,200		28,057
Rental equipment acquisitions				33,650		43,614
Accounts receivable, net (period end)		82,110	75,633	82,110		75,633
Rental equipment, at cost (period end)		892,339	854,076	892,339		854,076
Rental equipment, net book value (period end)		624,971	600,351	$ 624,971		$ 600,351
Utilization (period end)	[1]			76.80%		79.60%
Average utilization	[1]			78.20%		79.10%
TRS-RenTelco [Member]
Segment Reporting Information [Line Items]
Rental revenues				$ 53,548		$ 49,112
Rental related services revenues				1,496		1,562
Sales and other revenues				12,098		12,312
Total revenues		33,079	32,310	67,142		62,986
Depreciation of rental equipment				23,582		19,684
Gross profit				28,958		28,492
Selling and administrative expenses				12,236		12,063
Income from operations				16,722		16,429
Interest (expense) income allocation				(1,147)		(1,385)
Income (loss) before provision for income taxes				15,256		15,130
Rental equipment acquisitions				22,661		42,999
Accounts receivable, net (period end)		22,211	21,212	22,211		21,212
Rental equipment, at cost (period end)		337,987	307,639	337,987		307,639
Rental equipment, net book value (period end)		166,996	150,655	$ 166,996		$ 150,655
Utilization (period end)	[1]			65.70%		67.30%
Average utilization	[1]			64.70%		65.70%
Adler Tanks [Member]
Segment Reporting Information [Line Items]
Rental revenues				$ 27,549		$ 34,691
Rental related services revenues				10,883		13,988
Sales and other revenues				890		1,091
Total revenues		18,633	26,335	39,322		49,770
Depreciation of rental equipment				8,233		8,126
Gross profit				17,576		24,086
Selling and administrative expenses				13,177		14,894
Income from operations				4,399		9,192
Interest (expense) income allocation				(1,179)		(1,646)
Income (loss) before provision for income taxes				3,220		7,546
Rental equipment acquisitions				1,410		3,327
Accounts receivable, net (period end)		13,976	20,106	13,976		20,106
Rental equipment, at cost (period end)		316,497	315,571	316,497		315,571
Rental equipment, net book value (period end)		177,714	192,146	$ 177,714		$ 192,146
Utilization (period end)	[1]			43.10%		55.30%
Average utilization	[1]			45.90%		57.10%
Enviroplex [Member]
Segment Reporting Information [Line Items]
Sales and other revenues	[2]			$ 10,702		$ 3,877
Total revenues		9,199	1,072	10,702	[2]	3,877	[2]
Gross profit	[2]			4,053		1,443
Selling and administrative expenses	[2]			2,806		2,506
Income from operations	[2]			1,247		(1,063)
Interest (expense) income allocation	[2]			316		546
Income (loss) before provision for income taxes	[2]			1,563		(517)
Accounts receivable, net (period end)	[2]	$ 7,643	$ 4,067	$ 7,643		$ 4,067

[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 $11,979 and $3,877 for the six months ended June 30, 2020 and 2019, respectively. There were $1,277 inter-segment sales to Mobile Modular in the six months ended June 30, 2020, which required elimination in consolidation.  There were no inter-segment sales in the six months ended June 30, 2019.