Segment Information (Details 2) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment information
Revenue	$ 395,421,000	$ 306,755,000	$ 768,879,000	$ 702,733,000
Derivative gain not allocated to segments	19,699,000	136,067,000	19,514,000	87,352,000
Revenue deferral adjustment and other	1,437,000	1,324,000	2,801,000	3,217,000
Total revenue	415,120,000	442,822,000	788,393,000	790,085,000
Selling, general and administrative expenses	(25,499,000)	(21,700,000)	(50,741,000)	(46,748,000)
Depreciation	(71,562,000)	(41,336,000)	(139,579,000)	(80,918,000)
Amortization of intangible assets	(17,092,000)	(12,307,000)	(31,922,000)	(23,292,000)
Gain (loss) on disposal of property, plant and equipment	37,736,000	(1,342,000)	37,598,000	(2,328,000)
Accretion of asset retirement obligations	(157,000)	(160,000)	(509,000)	(396,000)
Income from operations	140,022,000	257,741,000	203,685,000	308,233,000
Earnings from unconsolidated affiliate	430,000	1,109,000	665,000	1,548,000
Interest income	62,000	159,000	211,000	231,000
Interest expense	(36,955,000)	(26,762,000)	(75,291,000)	(56,234,000)
Amortization of deferred financing costs and discount (a component of interest expense)	(1,784,000)	(1,245,000)	(3,614,000)	(2,515,000)
Loss on redemption of debt			(38,455,000)
Miscellaneous income, net	6,000	4,000	6,000	62,000
Income before provision for income tax	101,781,000	231,006,000	87,207,000	251,325,000
Management fee revenues unconsolidated affiliate	200,000	400,000	600,000	800,000
Total reportable segments
Segment information
Revenue	396,858,000	308,079,000	771,680,000	705,950,000
Portion of operating income (loss) attributable to non-controlling interests	(1,090,000)	(85,000)	(2,365,000)	(82,000)
Income from operations	177,472,000	144,698,000	339,200,000	337,448,000
Southwest Segment
Segment information
Revenue	227,842,000	206,551,000	436,208,000	441,927,000
Revenue deferral adjustment and other	200,000	200,000	400,000	400,000
Portion of operating income (loss) attributable to non-controlling interests	53,000	28,000	117,000	31,000
Income from operations	74,771,000	82,575,000	140,281,000	181,777,000
Northeast Segment
Segment information
Revenue	45,365,000	42,051,000	102,701,000	128,969,000
Revenue deferral adjustment and other	1,400,000	1,500,000	3,000,000	3,600,000
Income from operations	23,584,000	24,198,000	54,734,000	79,051,000
Unallocated Segment
Segment information
Derivative gain not allocated to segments	39,331,000	188,792,000	50,182,000	123,023,000
Revenue deferral adjustment and other	1,437,000	1,324,000	2,801,000	3,217,000
Compensation expense included in facility expenses not allocated to segments	(368,000)	(183,000)	(754,000)	(633,000)
Facility expenses adjustments	$ 2,688,000	$ 2,688,000	$ 5,376,000	$ 5,376,000