Condensed Consolidating Financial Information (Condensed Consolidating Statements of Cash Flows) (Details) (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Net cash provided by (used in) operating activities	$ 856,930	$ 809,053
Capital investments	(1,024,658)	(985,310)
Proceeds from sale of property and equipment	121,133	348,374
Transfers to restricted cash	(85,002)	(355,773)
Other	3,879	(2,445)
Net cash used in investing activities	(984,648)	(995,154)
Intercompany activities	0	0
Payments on current portion of long-term debt	(600)	(600)
Payments on revolving long-term debt	(1,717,600)	(1,297,000)
Borrowings under revolving long-term debt	1,840,600	1,478,100
Other	2,415	6,365
Net cash provided by financing activities	124,815	186,865
Effect of exchange rate changes on cash	127	0
Increase (decrease) in cash and cash equivalents	(2,776)	764
Cash and cash equivalents at beginning of year	16,055	13,184
Cash and cash equivalents at end of period	13,279	13,948
Parent [Member]
Net cash provided by (used in) operating activities	(29,781)	(29,605)
Capital investments	(35,347)	(23,175)
Proceeds from sale of property and equipment	0	0
Transfers to restricted cash	(85,002)	(355,773)
Other	7,244	6,364
Net cash used in investing activities	(113,105)	(372,584)
Intercompany activities	22,870	221,780
Payments on current portion of long-term debt	(600)	(600)
Payments on revolving long-term debt	(1,717,600)	(1,297,000)
Borrowings under revolving long-term debt	1,840,600	1,478,100
Other	2,415	6,365
Net cash provided by financing activities	147,685	408,645
Effect of exchange rate changes on cash	0
Increase (decrease) in cash and cash equivalents	4,799	6,456
Cash and cash equivalents at beginning of year	8,381	7,378
Cash and cash equivalents at end of period	13,180	13,834
Guarantors [Member]
Net cash provided by (used in) operating activities	763,933	701,961
Capital investments	(889,700)	(814,494)
Proceeds from sale of property and equipment	120,892	347,150
Transfers to restricted cash	0	0
Other	(11,339)	(13,016)
Net cash used in investing activities	(780,147)	(480,360)
Intercompany activities	8,583	(227,355)
Payments on current portion of long-term debt	0	0
Payments on revolving long-term debt	0	0
Borrowings under revolving long-term debt	0	0
Other	0	0
Net cash provided by financing activities	8,583	(227,355)
Effect of exchange rate changes on cash	0
Increase (decrease) in cash and cash equivalents	(7,631)	(5,754)
Cash and cash equivalents at beginning of year	7,631	5,776
Cash and cash equivalents at end of period	0	22
Non-Guarantors [Member]
Net cash provided by (used in) operating activities	122,778	136,697
Capital investments	(99,611)	(147,641)
Proceeds from sale of property and equipment	241	1,224
Transfers to restricted cash	0	0
Other	7,974	4,207
Net cash used in investing activities	(91,396)	(142,210)
Intercompany activities	(31,453)	5,575
Payments on current portion of long-term debt	0	0
Payments on revolving long-term debt	0	0
Borrowings under revolving long-term debt	0	0
Other	0	0
Net cash provided by financing activities	(31,453)	5,575
Effect of exchange rate changes on cash	127
Increase (decrease) in cash and cash equivalents	56	62
Cash and cash equivalents at beginning of year	43	30
Cash and cash equivalents at end of period	99	92
Eliminations [Member]
Net cash provided by (used in) operating activities	0	0
Capital investments	0	0
Proceeds from sale of property and equipment	0	0
Transfers to restricted cash	0	0
Other	0	0
Net cash used in investing activities	0	0
Intercompany activities	0	0
Payments on current portion of long-term debt	0	0
Payments on revolving long-term debt	0	0
Borrowings under revolving long-term debt	0	0
Other	0	0
Net cash provided by financing activities	0	0
Effect of exchange rate changes on cash	0
Increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of year	0	0
Cash and cash equivalents at end of period	$ 0	$ 0