Condensed Consolidating Financial Information (Condensed Consolidating Statements of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Net cash provided by (used in) operating activities	$ 372,138	$ 444,663
Capital investments	(483,634)	(557,631)
Proceeds from sale of property and equipment		651
Transfers from Restricted Cash	1,434
Other	1,038	1,770
Net cash used in investing activities	(481,162)	(555,210)
Payments on revolving long-term debt	(369,700)	(1,271,300)
Borrowings under revolving long-term debt	404,800	599,800
Proceeds from issuance of long-term debt		998,780
Other Items	37,845	(26,163)
Net cash provided by (used in) financing activities	72,945	301,117
Effect of exchange rate changes on cash	4	(30)
Increase (decrease) in cash and cash equivalents	(36,075)	190,540
Cash and cash equivalents at beginning of year	53,583	15,627
Cash and cash equivalents at end of period	17,508	206,167
Parent [Member]
Net cash provided by (used in) operating activities	(55,189)	(66,501)
Capital investments	(17,873)	(15,673)
Transfers from Restricted Cash	1,434
Other	6,607	4,085
Net cash used in investing activities	(9,832)	(11,588)
Intercompany activities	(38,036)	(32,324)
Payments on revolving long-term debt	(369,700)	(1,271,300)
Borrowings under revolving long-term debt	404,800	599,800
Proceeds from issuance of long-term debt		998,780
Other Items	37,845	(26,163)
Net cash provided by (used in) financing activities	34,909	268,793
Increase (decrease) in cash and cash equivalents	(30,112)	190,704
Cash and cash equivalents at beginning of year	47,491	14,711
Cash and cash equivalents at end of period	17,379	205,415
Guarantors [Member]
Net cash provided by (used in) operating activities	289,060	428,743
Capital investments	(453,651)	(502,036)
Proceeds from sale of property and equipment		651
Other	(5,762)	(9,440)
Net cash used in investing activities	(459,413)	(510,825)
Intercompany activities	164,365	82,571
Net cash provided by (used in) financing activities	164,365	82,571
Increase (decrease) in cash and cash equivalents	(5,988)	489
Cash and cash equivalents at beginning of year	5,988
Cash and cash equivalents at end of period		489
Non-Guarantors [Member]
Net cash provided by (used in) operating activities	138,267	82,421
Capital investments	(12,110)	(39,922)
Other	193	7,125
Net cash used in investing activities	(11,917)	(32,797)
Intercompany activities	(126,329)	(50,247)
Net cash provided by (used in) financing activities	(126,329)	(50,247)
Effect of exchange rate changes on cash	4	(30)
Increase (decrease) in cash and cash equivalents	25	(653)
Cash and cash equivalents at beginning of year	104	916
Cash and cash equivalents at end of period	$ 129	$ 263