Supplemental Condensed Consolidating Financial Information (Details 3) (USD $) In Thousands, unless otherwise specified	1 Months Ended								12 Months Ended
	Jan. 31, 2012	Dec. 31, 2011	Oct. 31, 2011	Jul. 31, 2011	Jan. 31, 2011	Apr. 30, 2010	Aug. 31, 2009	Jun. 30, 2009	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities									$ 414,698	$ 312,328	$ 223,101
Cash flows from investing activities:
Restricted cash									2,006	(28,001)
Capital expenditures									(551,281)	(458,668)	(486,623)
Acquisitions									(230,728)
Equity investments											(405)
Proceeds from disposal of property, plant and equipment									3,450	733	275
Proceeds from sale of unconsolidated affiliate											25,000
Net cash flows used in investing activities									(776,553)	(485,936)	(461,753)
Cash flows from financing activities:
Proceeds from revolving credit facility									1,182,200	494,404	725,200
Payments of revolving credit facility									(1,116,200)	(553,704)	(850,600)
Proceeds from long-term debt									1,199,000	500,000	117,000
Payments of long-term debt									(693,888)	(375,000)
Payments of premiums on redemption of long-term debt									(71,377)	(9,732)
Payments for debt issuance costs, deferred financing costs and registration costs									(20,163)	(20,912)	(8,554)
Acquisition of non-controlling interest, including transaction costs									(997,601)
Contributions to joint ventures, net									126,392	158,293	194,536
Proceeds from SMR Transaction											73,129
Proceeds from sale of equity interest in joint venture, net											60,654
Payments of SMR Liability									(1,875)	(1,354)
Proceeds from public equity offerings, net	38,000	521,000	251,000	185,100	138,200	142,300	120,900	57,700	1,095,488	142,255	178,565
Share-based payment activity									(5,270)	(3,736)	(1,385)
Payment of distributions									(285,285)	(187,208)	(155,462)
Net cash flows provided by financing activities									411,421	143,306	333,083
Net increase in cash									49,566	(30,302)	94,431
Cash and cash equivalents at beginning of year	117,016				67,450				67,450	97,752	3,321
Cash and cash equivalents at end of year		117,016							117,016	67,450	97,752
Parent
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities									(126,782)	(102,042)	(98,853)
Cash flows from investing activities:
Capital expenditures									(789)	(1,924)	(1,688)
Equity investments									(47,295)	(44,346)	(52,358)
Distributions from consolidated affiliates									50,718	41,167	13,984
Collection of (Investment in) intercompany notes, net									(37,990)	12,350	21,340
Net cash flows used in investing activities									(35,356)	7,247	(18,722)
Cash flows from financing activities:
Proceeds from revolving credit facility									1,182,200	494,404	725,200
Payments of revolving credit facility									(1,116,200)	(553,704)	(850,600)
Proceeds from long-term debt									1,199,000	500,000	117,000
Payments of long-term debt									(693,888)	(375,000)
Payments of premiums on redemption of long-term debt									(71,377)	(9,732)
Payments for debt issuance costs, deferred financing costs and registration costs									(20,163)	(20,912)	(8,054)
Acquisition of non-controlling interest, including transaction costs									(997,601)
Contributions to joint ventures, net											(5,464)
Proceeds from sale of equity interest in joint venture, net											(1,846)
Proceeds from public equity offerings, net									1,095,488	142,255	178,565
Share-based payment activity									(6,354)	(3,834)	(1,385)
Payment of distributions									(218,398)	(181,058)	(155,307)
Intercompany advances, net									(190,547)	102,376	119,466
Net cash flows provided by financing activities									162,160	94,795	117,575
Net increase in cash									22
Cash and cash equivalents at end of year		22							22
Guarantor Subsidiaries
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities									410,762	373,483	322,540
Cash flows from investing activities:
Capital expenditures									(162,517)	(123,005)	(209,485)
Acquisitions									(230,728)
Equity investments									(252,367)	(171,252)	(127,806)
Distributions from consolidated affiliates									68,651	22,246	31,227
Proceeds from disposal of property, plant and equipment									606	733	275
Proceeds from sale of equity interest in consolidated subsidiary											62,500
Proceeds from sale of unconsolidated affiliate											25,000
Net cash flows used in investing activities									(576,355)	(271,278)	(218,289)
Cash flows from financing activities:
Proceeds (Payments) of intercompany notes, net									14,990	(12,350)	(21,340)
Payments for debt issuance costs, deferred financing costs and registration costs											(500)
Contributions from parent, net									47,295	44,346	52,358
Proceeds from SMR Transaction											73,129
Payments of SMR Liability									(1,875)	(1,354)
Share-based payment activity									1,084	98
Payment of distributions									(50,718)	(41,167)	(13,984)
Intercompany advances, net									190,547	(102,376)	(119,466)
Net cash flows provided by financing activities									201,323	(112,803)	(29,803)
Net increase in cash									35,730	(10,598)	74,448
Cash and cash equivalents at beginning of year					63,850				63,850	74,448
Cash and cash equivalents at end of year		99,580							99,580	63,850	74,448
Non-Guarantor Subsidiaries
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities									137,961	46,852	5,249
Cash flows from investing activities:
Restricted cash									2,006	(28,001)
Capital expenditures									(399,992)	(347,231)	(281,285)
Proceeds from disposal of property, plant and equipment									7,617	7,527
Net cash flows used in investing activities									(390,369)	(367,705)	(281,285)
Cash flows from financing activities:
Proceeds (Payments) of intercompany notes, net									23,000
Contributions to joint ventures, net									378,759	329,545	327,401
Payment of distributions									(135,537)	(28,396)	(31,382)
Net cash flows provided by financing activities									266,222	301,149	296,019
Net increase in cash									13,814	(19,704)	19,983
Cash and cash equivalents at beginning of year					3,600				3,600	23,304	3,321
Cash and cash equivalents at end of year		17,414							17,414	3,600	23,304
Consolidating Adjustments
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities									(7,243)	(5,965)	(5,835)
Cash flows from investing activities:
Capital expenditures									12,017	13,492	5,835
Equity investments									299,662	215,598	179,759
Distributions from consolidated affiliates									(119,369)	(63,413)	(45,211)
Collection of (Investment in) intercompany notes, net									37,990	(12,350)	(21,340)
Proceeds from disposal of property, plant and equipment									(4,773)	(7,527)
Proceeds from sale of equity interest in consolidated subsidiary											(62,500)
Net cash flows used in investing activities									225,527	145,800	56,543
Cash flows from financing activities:
Proceeds (Payments) of intercompany notes, net									(37,990)	12,350	21,340
Contributions from parent, net									(47,295)	(44,346)	(52,358)
Contributions to joint ventures, net									(252,367)	(171,252)	(127,401)
Proceeds from sale of equity interest in joint venture, net											62,500
Payment of distributions									119,368	63,413	45,211
Net cash flows provided by financing activities									$ (218,284)	$ (139,835)	$ (50,708)