CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating Revenue:
Services	$ 137,735	$ 130,977	$ 123,722
Equipment	51,465	52,219	39,816
Total operating revenue	189,200	183,196	163,538
Costs and expenses:
Cost of sales, excluding depreciation and amortization	45,016	45,054	34,163
Cost of services, excluding depreciation and amortization	67,847	63,753	59,480
Selling, general and administrative expenses	28,759	28,257	27,184
Asset impairment	638	0	0
Depreciation and amortization	29,322	26,746	23,056
Total costs and expenses	171,582	163,810	143,883
Operating income	17,618	19,386	19,655
Other income (expense)
Interest and other income	19	44	63
Interest expense	(4,619)	(5,749)	(6,275)
Total other expense	(4,600)	(5,705)	(6,212)
Income before income taxes	13,018	13,681	13,443
Income tax provision	5,286	5,383	5,042
Net income	$ 7,732	$ 8,298	$ 8,401
Basic earnings per share	$ 0.57	$ 0.62	$ 0.63
Weighted average common shares outstanding	13,548,007	13,409,743	13,296,668
Diluted earnings per share	$ 0.57	$ 0.61	$ 0.63
Weighted average common and equivalent shares outstanding	13,606,217	13,528,039	13,419,647
Dividends per share	$ 0.585	$ 0.565	$ 0.545