Condensed Consolidating Statements of Operations (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 24, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Revenues:
Revenues		$ 149,707	$ 136,636	$ 432,360	$ 386,853
Costs and expenses:
Restructuring expenses			625	1,306	2,062	$ 2,886
Asset impairment charge and loss on divestiture, net	$ 98,278	98,278		98,278
Depreciation and amortization		16,191	15,935	50,206	46,941
Total costs and expenses		211,003	109,824	435,748	313,996
(Loss) income from operations		(61,296)	26,812	(3,388)	72,857
Other income (expense):
Interest income			4	6	20
Interest expense		(10,487)	(9,203)	(30,179)	(26,412)
Foreign currency exchange		24	(2)	69	(29)
(Loss) income before income tax provision		(71,759)	17,611	(33,492)	46,436
Income tax (benefit) provision		(19,594)	6,383	(11,182)	16,279
Net (loss) income		(52,165)	11,228	(22,310)	30,157
Eliminations
Other income (expense):
Interest income			(2,650)		(7,950)
Dividend income				(8,983)
Interest expense			2,650		7,950
(Loss) income before income tax provision				(8,983)
Net (loss) income				(8,983)
Guarantors
Revenues:
Revenues		125,785	113,140	361,989	320,522
Costs and expenses:
Restructuring expenses			625	1,306	2,062
Asset impairment charge and loss on divestiture, net		88,822		88,822
Depreciation and amortization		14,241	14,065	43,902	41,503
Total costs and expenses		183,266	92,570	371,322	264,012
(Loss) income from operations		(57,481)	20,570	(9,333)	56,510
Other income (expense):
Interest income			2,652	3	7,966
Dividend income				8,983
Interest expense		(10,287)	(11,727)	(29,545)	(33,981)
Foreign currency exchange				48
(Loss) income before income tax provision		(67,768)	11,495	(29,844)	30,495
Income tax (benefit) provision		(18,864)	5,402	(12,152)	13,650
Net (loss) income		(48,904)	6,093	(17,692)	16,845
Non-Guarantors
Revenues:
Revenues		23,922	23,496	70,371	66,331
Costs and expenses:
Asset impairment charge and loss on divestiture, net		9,456		9,456
Depreciation and amortization		1,950	1,870	6,304	5,438
Total costs and expenses		27,737	17,254	64,426	49,984
(Loss) income from operations		(3,815)	6,242	5,945	16,347
Other income (expense):
Interest income			2	3	4
Interest expense		(200)	(126)	(634)	(381)
Foreign currency exchange		24	(2)	21	(29)
(Loss) income before income tax provision		(3,991)	6,116	5,335	15,941
Income tax (benefit) provision		(730)	981	970	2,629
Net (loss) income		(3,261)	5,135	4,365	13,312
Rental
Revenues:
Revenues		140,924	127,695	406,149	360,288
Rental | Guarantors
Revenues:
Revenues		119,697	106,593	342,783	300,751
Rental | Non-Guarantors
Revenues:
Revenues		21,227	21,102	63,366	59,537
Sales
Revenues:
Revenues		8,716	8,438	25,700	24,817
Costs and expenses:
Cost of sales		5,770	5,519	16,925	16,039
Sales | Guarantors
Revenues:
Revenues		6,063	6,176	18,864	18,339
Costs and expenses:
Cost of sales		3,681	3,686	11,448	10,873
Sales | Non-Guarantors
Revenues:
Revenues		2,653	2,262	6,836	6,478
Costs and expenses:
Cost of sales		2,089	1,833	5,477	5,166
Other
Revenues:
Revenues		67	503	511	1,748
Other | Guarantors
Revenues:
Revenues		25	371	342	1,432
Other | Non-Guarantors
Revenues:
Revenues		42	132	169	316
Rental Selling and General Expenses
Costs and expenses:
Cost of sales		90,764	87,745	269,033	248,954
Rental Selling and General Expenses | Guarantors
Costs and expenses:
Cost of sales		76,522	74,194	225,844	209,574
Rental Selling and General Expenses | Non-Guarantors
Costs and expenses:
Cost of sales		$ 14,242	$ 13,551	$ 43,189	$ 39,380