UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME [Abstract]
Operating revenues	$ 77,513	$ 72,876	$ 230,976	$ 213,077
Operating expenses:
Cost of goods and services, exclusive of depreciation and amortization shown separately below	31,778	32,995	93,006	92,067
Selling, general and administrative, exclusive of depreciation and amortization shown separately below	17,481	17,680	49,966	47,788
Depreciation and amortization	14,992	16,794	45,034	47,860
Total operating expenses	64,251	67,469	188,006	187,715
Operating income	13,262	5,407	42,970	25,362
Other income (expense):
Interest expense	(2,050)	(2,323)	(6,270)	(5,641)
Gain (loss) on investments, net	348	212	526	815
Non-operating income, net	377	169	1,356	616
Income from continuing operations before income taxes	11,937	3,465	38,582	21,152
Income tax expense	5,220	2,050	15,672	9,608
Net income from continuing operations	6,717	1,415	22,910	11,544
Losses from discontinued operations, net of tax benefit of $0, $29, $0 and $97, respectively	0	(54)	0	(157)
Net income	6,717	1,361	22,910	11,387
Other comprehensive income:
Unrealized (loss) gain on interest rate hedge, net of tax	(398)	(1,136)	2,909	(1,136)
Comprehensive income	$ 6,319	$ 225	$ 25,819	$ 10,251
Basic and diluted net income (loss) per share:
Net income from continuing operations (in dollars per share)	$ 0.28	$ 0.06	$ 0.95	$ 0.48
Losses from discontinued operations (in dollars per share)	$ 0	$ 0	$ 0	$ (0.01)
Net income (in dollars per share)	$ 0.28	$ 0.06	$ 0.95	$ 0.47
Weighted average shares outstanding, basic (in shares)	24,010	23,875	23,993	23,858
Weighted average shares, diluted (in shares)	24,125	23,956	24,078	23,905