Condensed Consolidating Financial Information (Condensed Consolidating Statements of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Net cash provided by (used in) operating activities	$ 877,552	$ 837,390
Capital investments	(1,175,634)	(1,140,661)
Proceeds from sale of property and equipment		(174,337)
Transfers to restricted cash		(167,750)
Transfers from restricted cash	8,542	23,366
Other	5,628	8,895
Net cash used in investing activities	(1,161,464)	(1,101,813)
Payments on current portion of long-term debt	(600)	(600)
Payments on revolving long-term debt	(1,233,150)	(1,273,700)
Borrowings under revolving long-term debt	1,463,150	602,200
Proceeds from issuance of long-term debt		998,780
Other Items	26,497	(36,370)
Net cash provided by (used in) financing activities	255,897	290,310
Effect of exchange rate changes on cash	117	(15)
Increase (decrease) in cash and cash equivalents	(27,898)	25,872
Cash and cash equivalents at beginning of year	53,583	15,627
Cash and cash equivalents at end of period	25,685	41,499
Parent [Member]
Net cash provided by (used in) operating activities	(30,843)	(51,093)
Capital investments	(12,156)	(18,079)
Transfers to restricted cash		(167,750)
Transfers from restricted cash	8,542	23,366
Other	(73)	90
Net cash used in investing activities	(3,687)	(162,373)
Intercompany activities	(243,555)	(54,667)
Payments on current portion of long-term debt	(600)	(600)
Payments on revolving long-term debt	(1,233,150)	(1,273,700)
Borrowings under revolving long-term debt	1,463,150	602,200
Proceeds from issuance of long-term debt		998,780
Other Items	26,497	(36,370)
Net cash provided by (used in) financing activities	12,342	235,643
Increase (decrease) in cash and cash equivalents	(22,188)	22,177
Cash and cash equivalents at beginning of year	47,491	14,711
Cash and cash equivalents at end of period	25,303	36,888
Guarantors [Member]
Net cash provided by (used in) operating activities	651,169	624,945
Capital investments	(1,084,093)	(1,032,169)
Proceeds from sale of property and equipment		(168,391)
Other	1,894	(2,287)
Net cash used in investing activities	(1,082,199)	(866,065)
Intercompany activities	425,042	245,329
Net cash provided by (used in) financing activities	425,042	245,329
Increase (decrease) in cash and cash equivalents	(5,988)	4,209
Cash and cash equivalents at beginning of year	5,988
Cash and cash equivalents at end of period		4,209
Non-Guarantors [Member]
Net cash provided by (used in) operating activities	257,226	263,538
Capital investments	(79,385)	(90,413)
Proceeds from sale of property and equipment		(5,946)
Other	3,807	11,092
Net cash used in investing activities	(75,578)	(73,375)
Intercompany activities	(181,487)	(190,662)
Net cash provided by (used in) financing activities	(181,487)	(190,662)
Effect of exchange rate changes on cash	117	(15)
Increase (decrease) in cash and cash equivalents	278	(514)
Cash and cash equivalents at beginning of year	104	916
Cash and cash equivalents at end of period	$ 382	$ 402