CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating Revenue:
Equipment	$ 39,816	$ 39,406	$ 27,857
Services	123,722	122,841	111,245
Total operating revenue	163,538	162,247	139,102
Costs and expenses:
Cost of sales, excluding depreciation and amortization	34,163	33,300	24,869
Cost of services, excluding depreciation and amortization	59,480	60,897	52,211
Selling, general and administrative expenses	27,184	25,060	22,260
Depreciation	22,702	21,665	20,176
Amortization of intangibles	354	357	1,001
Total costs and expenses	143,883	141,279	120,517
Operating income	19,655	20,968	18,585
Other income and expense:
Interest and other income	63	73	105
Interest expense	(6,275)	(4,084)	(5,540)
Total other (expense)	(6,212)	(4,011)	(5,435)
Income before income taxes	13,443	16,957	13,150
Income tax provision	5,042	4,365	1,048
Net income	$ 8,401	$ 12,592	$ 12,102
Basic earnings per share (in dollars per share)	$ 0.63	$ 0.95	$ 0.93
Weighted average common shares outstanding (in shares)	13,369,991	13,233,874	13,061,266
Diluted earnings per share (in dollars per share)	$ 0.63	$ 0.95	$ 0.93
Weighted average common and equivalent shares outstanding (in shares)	13,382,522	13,237,195	13,061,861
Dividends per share (in dollars per share)	$ 0.545	$ 0.525	$ 0.52