Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Current assets	$ 206,823	$ 116,523
Current assets held for sale	1,882	3,874
Property and equipment, net	1,487,674	1,240,917
Investment in subsidiaries	0	0
LONG-TERM ASSETS HELD FOR SALE	132,626	78,731
Other assets	54,991	87,635
TOTAL ASSETS	1,883,996	1,527,680
Current liabilities	250,255	267,082
Current liabilities associated with assets held for sale	48,663	4,238
Long-term liabilities	976,515	724,076
LONG-TERM LIABILITIES ASSOCIATED WITH ASSETS HELD FOR SALE	23,547	22,429
Shareholders’ equity	585,016	509,855	456,636	247,609
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	1,883,996	1,527,680
Parent Company [Member]
Current assets	1,689,430	1,349,841
Current assets held for sale	0	0
Property and equipment, net	23,041	100,329
Investment in subsidiaries	14,588	(58,764)
LONG-TERM ASSETS HELD FOR SALE	24,488	687
Other assets	35,095	38,852
TOTAL ASSETS	1,786,642	1,430,945
Current liabilities	179,221	150,793
Current liabilities associated with assets held for sale	9,880	0
Long-term liabilities	973,003	724,801
LONG-TERM LIABILITIES ASSOCIATED WITH ASSETS HELD FOR SALE	0	0
Shareholders’ equity	624,538	555,351
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	1,786,642	1,430,945
Combined Guarantor Subsidiaries [Member]
Current assets	130,487	71,018
Current assets held for sale	0	0
Property and equipment, net	1,443,064	1,131,672
Investment in subsidiaries	0	0
LONG-TERM ASSETS HELD FOR SALE	0	0
Other assets	16,928	54,062
TOTAL ASSETS	1,590,479	1,256,752
Current liabilities	1,631,887	1,368,456
Current liabilities associated with assets held for sale	0	0
Long-term liabilities	3,512	2,183
LONG-TERM LIABILITIES ASSOCIATED WITH ASSETS HELD FOR SALE	0	0
Shareholders’ equity	(44,920)	(113,887)
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	1,590,479	1,256,752
Combined Non-Guarantor Subsidiaries [Member]
Current assets	0	0
Current assets held for sale	1,882	3,874
Property and equipment, net	0	0
Investment in subsidiaries	0	0
LONG-TERM ASSETS HELD FOR SALE	108,138	78,044
Other assets	11,818	0
TOTAL ASSETS	121,838	81,918
Current liabilities	0	128
Current liabilities associated with assets held for sale	38,783	4,238
Long-term liabilities	0	0
LONG-TERM LIABILITIES ASSOCIATED WITH ASSETS HELD FOR SALE	23,547	22,429
Shareholders’ equity	59,508	55,123
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	121,838	81,918
Eliminations [Member]
Current assets	(1,613,094)	(1,304,336)
Current assets held for sale	0	0
Property and equipment, net	21,569	8,916
Investment in subsidiaries	(14,588)	58,764
LONG-TERM ASSETS HELD FOR SALE	0	0
Other assets	(8,850)	(5,279)
TOTAL ASSETS	(1,614,963)	(1,241,935)
Current liabilities	(1,560,853)	(1,252,295)
Current liabilities associated with assets held for sale	0	0
Long-term liabilities	0	(2,908)
LONG-TERM LIABILITIES ASSOCIATED WITH ASSETS HELD FOR SALE	0	0
Shareholders’ equity	(54,110)	13,268
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ (1,614,963)	$ (1,241,935)