CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ 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
(Loss) earnings per share:
Basic		$ (1.18)	$ 0.25	$ (0.50)	$ 0.68
Diluted		$ (1.18)	$ 0.25	$ (0.50)	$ 0.68
Weighted average number of common and common share equivalents outstanding:
Basic		44,323	44,039	44,275	44,030
Diluted		44,323	44,206	44,275	44,190
Cash dividends declared per share		$ 0.25	$ 0.23	$ 0.75	$ 0.68
Rental
Revenues:
Revenues		$ 140,924	$ 127,695	$ 406,149	$ 360,288
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
Other
Revenues:
Revenues		67	503	511	1,748
Rental Selling and General Expenses
Costs and expenses:
Cost of sales		$ 90,764	$ 87,745	$ 269,033	$ 248,954