Condensed Consolidated Statement of Partners' Capital and Noncontrolling Interest (USD $) In Thousands, except Share data	Total USD ($)	Capital Unit, Class A [Member]	Common Unitholders [Member] USD ($)	General Partner Interest [Member] USD ($)	Accumulated Other Comprehensive Loss [Member] USD ($)	Noncontrolling Interest [Member] USD ($)
Balance at Dec. 31, 2011	$ 3,531,076		$ 3,173,090	$ 329,876	$ (4,759)	$ 32,869
Balance - (in Units) at Dec. 31, 2011		157,437,608
Common unit offering, net of costs - (in Units)		12,650,000
Common unit offering, net of costs	297,302		297,302
Issuance of common units under LTIP, net of forfeitures and tax withholding - (in Units)		9,296
Issuance of common units under LTIP, net of forfeitures and tax withholdings - (in dollars)	(119)		(119)
Unit-based compensation expenses	1,289		1,289
Partner distributions	76,139		(72,891)	(3,248)
Accrued distributions to phantom units	(32)		(32)
Net income (loss)	28,900		26,013	2,488		399
Payments of Dividends, Noncontrolling Interest	5,133					5,133
Distributions to Series A Preferred Units	(1,945)		(1,911)	(34)
Accretion of Series A Preferred Units	(1,052)		(1,034)	(18)
Net cash flow hedge amounts reclassified to earnings	3,665				3,665
Balance at Mar. 31, 2012	$ 3,788,078		$ 3,421,707	$ 329,064	$ (1,094)	$ 38,401
Balance - (in Units) at Mar. 31, 2012		170,096,904