UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current Assets
Cash and cash equivalents	$ 73,402	$ 71,086
Accounts receivable, net	25,019	25,274
Income taxes receivable	4,789	4,705
Materials and supplies	8,011	9,789
Prepaid expenses and other	5,548	4,749
Deferred income taxes	1,028	832
Total current assets	117,797	116,435
Investments, including $2,190 and $2,064 carried at fair value	8,578	8,214
Property, plant and equipment, net	386,581	365,474
Other Assets
Intangible assets, net	72,625	74,942
Deferred charges and other assets, net	10,501	5,675
Net other assets	83,126	80,617
Total assets	596,082	570,740
Current Liabilities
Current maturities of long-term debt	517	1,977
Accounts payable	34,721	31,729
Advanced billings and customer deposits	11,282	11,190
Accrued compensation	2,314	2,671
Accrued liabilities and other	10,316	10,573
Total current liabilities	59,150	58,140
Long-term debt, less current maturities	230,200	230,200
Other Long-Term Liabilities
Deferred income taxes	60,498	57,896
Deferred lease payable	5,582	4,903
Asset retirement obligations	6,086	5,896
Other liabilities	6,454	5,857
Total other liabilities	78,620	74,552
Commitments and Contingencies
Shareholders' Equity
Common stock	25,452	24,688
Accumulated other comprehensive income (loss)	2,444	(863)
Retained earnings	200,216	184,023
Total shareholders' equity	228,112	207,848
Total liabilities and shareholders' equity	$ 596,082	$ 570,740