Partners' Equity Narrative (Details) (USD $)	12 Months Ended															12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Phantom Share Units (PSUs) [Member]	Dec. 31, 2011 Phantom Share Units (PSUs) [Member]	Dec. 31, 2010 Phantom Share Units (PSUs) [Member]	Dec. 31, 2012 Fixed Price Options [Member]	Dec. 31, 2012 Performance Units [Member]	Dec. 31, 2010 Performance Units [Member]	Dec. 31, 2009 Performance Units [Member]	Dec. 31, 2012 Restricted Stock Units (RSUs) [Member]	Dec. 31, 2012 Restricted Units March 2012 Award [Member]	Dec. 31, 2012 Restricted Units October 2012 Award [Member]	Dec. 31, 2012 2012 Option Awards [Member]	Dec. 31, 2012 Variable Price Options [Member]	Dec. 31, 2012 Prior Option Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Special L.P. interests	$ 5,290,000	$ 5,290,000
Unit options and other forms of equity authorized under equity incentive plan	4,800,000
Non-option equity instruments awarded				15,000				46,759				93,517	97,394
Grant price per unit				27.91				29.53				29.53	35.52
Compensation expense related to non-option equity instruments	4,476,000	(239,000)	(89,000)	3,400,000	5,400,000	3,500,000		3,354,000	2,605,000	864,000	1,220,400
Distribution equivalent liability	150,900
Intrinsic value of restricted units that vested	100,000
Non-option equity instruments, units outstanding				225,459				161,619
Non-option equity instruments, vested units outstanding				147,017
Closing price per unit				$ 33.45				$ 33.45
Aggregate market value of vested units, current portion				500,000	9,700,000			3,782,000
Aggregate market value of vested units, noncurrent portion				4,400,000	1,600,000
Unamortized compensation related to unvested phantom unit awards				2,600,000			1,000,000	1,100,000			5,000,600
Unamortized compensation related to unvested phantom unit awards, period for recognition				1 year 10 months 24 days			2 years 3 months 18 days	2 years			2 years 6 months
Award vesting period											3 years			3 years		5 years
Expected term, maximum	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	37.20%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	2.31%
Per-unit distribution made to limited partners	$ 1.6
Annual vesting percentage for 2012 and 2013								50.00%
Unit options outstanding	210,504	0					293,422								600
Unit options granted in period	280,672	0
Unit options granted in period, fair value per share	$ 4.92
Aggregate market value of contingently issuable units								541,403	2,067,000
Total intrinsic value of options exercised	400,000	0	500,000
Non-cash compensation expense relating to unit options	$ 345,228