CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Revenue:
Equipment	$ 52,219	$ 39,816	$ 39,406
Services	130,977	123,722	122,841
Total operating revenue	183,196	163,538	162,247
Costs and expenses:
Cost of sales, excluding depreciation and amortization	45,054	34,163	33,300
Cost of services, excluding depreciation and amortization	63,753	59,480	60,897
Selling, general and administrative expenses	28,257	27,184	25,060
Depreciation and amortization	26,746	23,056	22,022
Total costs and expenses	163,810	143,883	141,279
Operating income	19,386	19,655	20,968
Other income and expense:
Interest and other income	44	63	73
Interest expense	(5,749)	(6,275)	(4,084)
Total other income (expense)	(5,705)	(6,212)	(4,011)
Income before income taxes	13,681	13,443	16,957
Income tax provision	5,383	5,042	4,365
Net income	$ 8,298	$ 8,401	$ 12,592
Basic earnings per share	$ 0.62	$ 0.63	$ 0.95
Weighted Average Number of Shares Outstanding, Basic	13,409,743	13,296,668	13,188,674
Diluted earnings per share	$ 0.61	$ 0.63	$ 0.95
Weighted average common and equivalent shares outstanding	13,528,039	13,419,647	13,239,113
Dividends per share	$ 0.565	$ 0.545	$ 0.525