UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME [Abstract]
Operating revenues	$ 76,010	$ 68,823
Operating expenses:
Cost of goods and services, exclusive of depreciation and amortization shown separately below	30,700	29,029
Selling, general and administrative, exclusive of depreciation and amortization shown separately below	16,129	15,170
Depreciation and amortization	13,972	15,807
Total operating expenses	60,801	60,006
Operating income	15,209	8,817
Other income (expense):
Interest expense	(2,152)	(1,795)
Gain on investments, net	148	471
Non-operating income, net	520	188
Income from continuing operations before income taxes	13,725	7,681
Income tax expense	5,374	3,273
Net income from continuing operations	8,351	4,408
Income from discontinued operations, net of tax (expense) of $0 and $(38), respectively	0	58
Net income	8,351	4,466
Other comprehensive income:
Unrealized gain on interest rate hedge, net of tax	532	0
Comprehensive income	$ 8,883	$ 4,466
Basic and diluted net income per share:
Net income from continuing operations (in dollars per share)	$ 0.35	$ 0.19
Net income from discontinued operations (in dollars per share)	$ 0	$ 0
Net income (in dollars per share)	$ 0.35	$ 0.19
Weighted average shares outstanding, basic (in shares)	23,973	23,843
Weighted average shares, diluted (in shares)	24,032	23,868