Segment Reporting - Summarized Financial Information for Company's Reportable Segments (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Rental revenues		$ 89,506	$ 82,696
Rental related services revenues		24,511	21,455
Sales and other revenues		15,436	17,857
Total revenues		129,453	122,008
Depreciation of rental equipment		21,638	18,961
Gross profit		61,656	57,005
Selling and administrative expenses		31,954	29,695
Income from operations		29,702	27,310
Interest (expense) income allocation		(2,652)	(3,108)
Income (loss) before provision for income taxes		26,614	24,251
Rental equipment acquisitions		35,415	35,440
Accounts receivable, net (period end)		125,834	119,403	$ 128,099
Rental equipment, at cost (period end)		1,540,498	1,436,251	1,520,411
Rental equipment, net book value (period end)		975,709	912,878	$ 967,500
Mobile Modular [Member]
Segment Reporting Information [Line Items]
Rental revenues		47,410	42,261
Rental related services revenues		18,144	14,471
Sales and other revenues		7,644	8,360
Total revenues		73,198	65,092
Depreciation of rental equipment		5,669	5,408
Gross profit		36,859	30,879
Selling and administrative expenses		17,418	15,370
Income from operations		19,441	15,509
Interest (expense) income allocation		(1,547)	(1,883)
Income (loss) before provision for income taxes		17,894	13,626
Rental equipment acquisitions		19,135	20,938
Accounts receivable, net (period end)		79,220	71,816
Rental equipment, at cost (period end)		883,076	834,883
Rental equipment, net book value (period end)		$ 620,138	$ 585,248
Utilization (period end)	[1]	78.30%	78.90%
Average utilization	[1]	78.70%	78.80%
TRS-RenTelco [Member]
Segment Reporting Information [Line Items]
Rental revenues		$ 27,536	$ 23,623
Rental related services revenues		826	708
Sales and other revenues		5,701	6,345
Total revenues		34,063	30,676
Depreciation of rental equipment		11,832	9,520
Gross profit		14,757	13,667
Selling and administrative expenses		6,361	5,970
Income from operations		8,396	7,697
Interest (expense) income allocation		(647)	(678)
Income (loss) before provision for income taxes		7,313	7,068
Rental equipment acquisitions		16,075	12,808
Accounts receivable, net (period end)		23,949	20,925
Rental equipment, at cost (period end)		341,841	286,469
Rental equipment, net book value (period end)		$ 174,762	$ 132,607
Utilization (period end)	[1]	63.80%	66.50%
Average utilization	[1]	65.30%	64.30%
Adler Tanks [Member]
Segment Reporting Information [Line Items]
Rental revenues		$ 14,560	$ 16,812
Rental related services revenues		5,541	6,276
Sales and other revenues		588	347
Total revenues		20,689	23,435
Depreciation of rental equipment		4,137	4,033
Gross profit		9,509	11,423
Selling and administrative expenses		6,824	7,080
Income from operations		2,685	4,343
Interest (expense) income allocation		(661)	(827)
Income (loss) before provision for income taxes		2,024	3,516
Rental equipment acquisitions		205	1,694
Accounts receivable, net (period end)		15,967	19,151
Rental equipment, at cost (period end)		315,581	314,899
Rental equipment, net book value (period end)		$ 180,809	$ 195,023
Utilization (period end)	[1]	47.00%	59.20%
Average utilization	[1]	47.80%	57.30%
Enviroplex [Member]
Segment Reporting Information [Line Items]
Sales and other revenues	[2]	$ 1,503	$ 2,805
Total revenues	[2]	1,503	2,805
Gross profit	[2]	531	1,036
Selling and administrative expenses	[2]	1,351	1,275
Income from operations	[2]	(820)	(239)
Interest (expense) income allocation	[2]	203	280
Income (loss) before provision for income taxes	[2]	(617)	41
Accounts receivable, net (period end)	[2]	$ 6,698	$ 7,511

[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 $2,778 and $2,805 for the three months ended March 31, 2020 and 2019, respectively. There were $1,275 inter-segment sales to Mobile Modular in the three months ended March 31, 2020, which required elimination in consolidation.  There were no inter-segment sales in the three months ended March 31, 2019.