Condensed Consolidated Statements Of Partners' Capital (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Statement of Partners' Capital [Abstract]
Partners' capital, January 1, units	81,202,752	71,965,000
Partners' capital, January 1, value	$ 916,495	$ 792,638
Net income	22,846	19,604
Cash distributions	39,390	31,677
Issuance of common units for cash, net, units	0	5,750,000
Issuance of common units for cash, net, value	0	169,524
Conversion of waiver units, units	0	1,738,000
Conversion of waiver units, value	0	0
Other, units	0	12,000
Other, value	0	500
Partners' capital, March 31, units	81,202,752	79,465,000
Partners' capital, March 31, value	$ 899,951	$ 950,589

Limited Partners Capital Account Units, Other Increase (Decrease)

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The amount of the limited partners' ownership interests.

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The number of limited partner units outstanding.

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Total distributions to each class of partners (i.e., general, limited and preferred partners).

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Total change in each class of partners' capital accounts during the year due to exchanges and conversions. Partners include general, limited and preferred partners.

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Total change in each class of partners' capital accounts during the year due to the sale of units. All partners include general, limited and preferred partners.

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The number of units converted into shares of each class of partners' capital account. Units represent shares of ownership of the general, limited, and preferred partners.

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Total units issued during the year due to the sale of units. All partners include general, limited and preferred partners.

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This element represents movements included in the statement of changes in partners' capital which are not separately disclosed or provided for elsewhere in the taxonomy.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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