Related Party Transactions - Related Party Transactions Excluding Expenses Allocated to Partnership as Part of Result of Dropdown Predecessor (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Related Party Transaction [Line Items]
Revenues	$ 392,251	$ 379,975	$ 374,008
Vessel operating expenses	86,347	89,046	84,577
General and administrative	27,149	24,120	23,247
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Revenues	37,630	35,068	36,512
Vessel operating expenses	2,548	2,742	3,791
General and administrative	$ 19,710	$ 15,468	$ 14,919

Revenue from transporting cargo and freight between locations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(d))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-AIR

-Paragraph 4

-IssueDate 2003-05-01

-Chapter 3

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

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- Definition

The total amount of other operating cost and expense items that are associated with the entity's normal revenue producing operation.

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- Details

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