Incentive Compensation Plans (Details) (USD $)	12 Months Ended										1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Phantom units	Dec. 31, 2010 Phantom units	Dec. 31, 2009 Phantom units	Dec. 31, 2011 Distribution equivalent rights	Dec. 31, 2010 Distribution equivalent rights	Dec. 31, 2009 Distribution equivalent rights	Dec. 31, 2011 2008 LTIP Y	Apr. 30, 2010 2008 LTIP TSR Performance Units	Dec. 31, 2012 2008 LTIP TSR Performance Units	Dec. 31, 2011 2008 LTIP TSR Performance Units Y	Dec. 31, 2010 2008 LTIP TSR Performance Units	Jan. 31, 2010 2008 LTIP Unrestricted units	Dec. 31, 2012 2008 LTIP Performance units	Dec. 31, 2011 2008 LTIP Performance units	Dec. 31, 2010 2008 LTIP Performance units	Dec. 31, 2009 2008 LTIP Performance units	Feb. 28, 2008 2006 Hydrocarbon Plan and 1996 Hydrocarbon Plan unit	Dec. 31, 2011 2002 LTIP Plan Phantom units	Dec. 31, 2010 2002 LTIP Plan Phantom units	Dec. 31, 2009 2002 LTIP Plan Phantom units	Dec. 31, 2011 2008 LTIP, 2006 Hydrocarbon Plan and 1996 Hydrocarbon Plan Phantom units	Dec. 31, 2010 2008 LTIP, 2006 Hydrocarbon Plan and 1996 Hydrocarbon Plan Phantom units	Dec. 31, 2009 2008 LTIP, 2006 Hydrocarbon Plan and 1996 Hydrocarbon Plan Phantom units
Share-based compensation arrangement by share-based payment award
Total share-based compensation expense	$ 13,925,000	$ 16,784,000	$ 8,772,000	$ 13,479,000	$ 15,319,000	$ 7,448,000	$ 446,000	$ 1,465,000	$ 1,324,000				$ 4,800,000	$ 4,500,000	$ 4,800,000		$ 0	$ 0	$ 500,000
Total compensation expense not yet recognized										12,100,000			200,000
Unrecognized compensation costs on unvested awards, weighted average period of recognition (in years)										0.8
Vesting period of share-based awards (in years)																	3 years				3 years			3 years
Cash paid for taxes related to vesting of share-based payment awards related to tax withholding for share-based compensation	6,354,000	3,834,000	1,385,000																		400,000	400,000	200,000	6,000,000	3,400,000	1,100,000
Common units provided for issuance to employees and affiliates as share-based payment awards (in units)										2,500,000
Performance period used in computation of total unitholder return (in years)													3
Percentage of units vested if relative ranking is less than 40th percentile (Expressed as a decimal)													0.00%
Percentage of units vested if relative ranking ranges from 40th to 60th percentile (Expressed as a decimal)													50.00%
Percentage of units vested if relative ranking ranges from 60th to 80th percentile (Expressed as a decimal)													75.00%
Percentage of units vested if relative ranking ranges from 80th to 100th percentile (Expressed as a decimal)													100.00%
Percentage of increase or decrease in the number of units to vest, which the board can approve based on certain performance criteria (Expressed as a decimal)													25.00%
Number of units that vested based on actual performance with regards to the market criteria (in units)												141,000	141,000
Number of units that vested based on actual performance with regards to the market criteria and performance criteria (in units)												35,250	35,250
Percentage of units that will vest based on actual performance with regards to the market criteria (Expressed as a decimal)													75.00%
Percentage of units that will vest based on actual performance with regards to the market criteria and performance criteria (Expressed as a decimal)													25.00%
Unit activity
Unvested at the beginning of the period (in units)												141,000	282,000			141,000					23,645	69,555	145,927	1,329,160	977,241	909,306
Granted (in units)											282,000	35,250	35,250		166,000									309,629	736,688	442,035
Vested (in units)													(176,250)								(23,645)	(44,942)	(69,652)	(396,934)	(363,502)	(309,052)
Forfeited (in units)																(141,000)						(968)	(6,720)	(306,346)	(21,267)	(65,048)
Unvested at the end of the period (in units)													141,000	282,000			141,000					23,645	69,555	935,509	1,329,160	977,241
Weighted-average Grant-date Fair Value
Unvested at the beginning of the period (in dollars per unit)																					$ 33.83	$ 32.75	$ 31.45	$ 25.29	$ 22.00	$ 31.80
Granted (in dollars per unit)																								$ 42.75	$ 30.25	$ 8.64
Vested (in dollars per unit)																					$ 33.83	$ 32.15	$ 29.94	$ 27.04	$ 26.85	$ 31.93
Forfeited (in dollars per unit)																						$ 34.00	$ 33.64	$ 31.66	$ 19.28	$ 20.96
Unvested at the end of the period (in dollars per unit)																						$ 33.83	$ 32.75	$ 28.50	$ 25.29	$ 22.00
Total grant-date fair value of units outstanding																	1,200,000
Other Award Information
Shares of restricted stock granted under an equity-based compensation plan which are converted in connection with merger																				25,897
Number of phantom units issued against restricted stock converted in connection with merger (in units)																				49,354
Total fair value of phantom units vested during the period													4,900,000								1,000,000	1,300,000	900,000	10,700,000	9,800,000	9,900,000
Total intrinsic value of phantom units vested during the period													$ 4,900,000								$ 1,000,000	$ 1,300,000	$ 900,000	$ 10,700,000	$ 9,800,000	$ 9,900,000