Consolidated Statements of Cash Flows	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Cash Flows from Operating Activities:
Net income	$ 153,920,000	$ 38,251,000	$ 40,470,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	78,416,000	81,179,000	84,280,000
Impairment of rental assets	1,639,000	0	0
Provision for doubtful accounts	1,480,000	1,892,000	2,149,000
Share-based compensation	3,198,000	3,091,000	3,399,000
Gain on sale of used rental equipment	(17,733,000)	(13,739,000)	(11,902,000)
Foreign currency exchanges (gain) loss	(334,000)	121,000	488,000
Amortization of debt issuance costs	50,000	51,000	52,000
Change in:
Accounts receivable	(10,475,000)	(3,752,000)	3,628,000
Income taxes receivable		11,000,000	(11,000,000)
Prepaid expenses and other assets	3,124,000	3,219,000	12,910,000
Accounts payable and accrued liabilities	4,015,000	10,426,000	(1,812,000)
Deferred income	1,720,000	1,211,000	7,149,000
Deferred income taxes	(96,631,000)	7,745,000	14,449,000
Net cash provided by operating activities	122,389,000	140,695,000	144,260,000
Cash Flows from Investing Activities:
Purchases of rental equipment	(94,579,000)	(79,038,000)	(131,037,000)
Purchases of property, plant and equipment	(14,617,000)	(10,548,000)	(9,321,000)
Proceeds from sales of used rental equipment	38,344,000	29,406,000	26,214,000
Net cash used in investing activities	(70,852,000)	(60,180,000)	(114,144,000)
Cash Flows from Financing Activities:
Net borrowings (repayments) under bank lines of credit	(2,902,000)	(35,066,000)	18,963,000
Principal payments on Series A senior notes	(20,000,000)	(20,000,000)	(20,000,000)
Borrowings under Series C senior notes			60,000,000
Proceeds from the exercise of stock options		37,000	2,149,000
Taxes paid related to net share settlement of stock awards	(2,072,000)	(1,287,000)	(1,560,000)
Repurchase of common stock			(63,953,000)
Payment of dividends	(24,876,000)	(24,448,000)	(25,779,000)
Net cash used in financing activities	(49,850,000)	(80,764,000)	(30,180,000)
Effect of foreign currency exchange rate changes on cash	(38,000)	(2,000)
Net increase (decrease) in cash	1,649,000	(251,000)	(64,000)
Cash balance, beginning of period	852,000	1,103,000	1,167,000
Cash balance, end of period	2,501,000	852,000	1,103,000
Supplemental Disclosure of Cash Flow Information:
Interest paid, during the period	11,825,000	12,436,000	10,041,000
Net income taxes paid, during the period	29,504,000	15,555,000	2,498,000
Dividends accrued during the period, not yet paid	6,260,000	6,147,000	6,019,000
Rental equipment acquisitions, not yet paid	$ 6,405,000	$ 2,876,000	$ 7,280,000