Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues
Rental	$ 289,417	$ 271,388	$ 273,696
Rental related services	78,068	75,859	73,314
Rental operations	367,485	347,247	347,010
Sales	91,500	74,410	55,385
Other	3,049	2,423	2,149
Total revenues	462,034	424,080	404,544
Direct costs of rental operations:
Depreciation of rental equipment	69,908	72,197	75,213
Rental related services	60,029	59,044	57,144
Other	65,472	60,130	58,511
Total direct costs of rental operations	195,409	191,371	190,868
Cost of sales	60,280	48,542	36,769
Total costs of revenues	255,689	239,913	227,637
Gross profit	206,345	184,167	176,907
Selling and administrative expenses	111,605	104,908	99,950
Income from operations	94,740	79,259	76,957
Other income (expense):
Interest expense	(11,622)	(12,207)	(10,092)
Foreign currency exchange gain (loss)	334	(121)	(488)
Income before provision for income taxes	83,452	66,931	66,377
(Benefit) provision for income taxes	(70,468)	28,680	25,907
Net income	$ 153,920	$ 38,251	$ 40,470
Earnings per share:
Basic	$ 6.41	$ 1.60	$ 1.60
Diluted	$ 6.34	$ 1.60	$ 1.59
Shares used in per share calculations:
Basic	23,999	23,900	25,369
Diluted	24,269	23,976	25,457
Cash dividends declared per share	$ 1.04	$ 1.02	$ 1.00