Partnership's Outstanding Debt (Parenthetical) (Detail)	6 Months Ended	12 Months Ended		6 Months Ended	12 Months Ended		6 Months Ended	12 Months Ended
Jun. 30, 2013 5.875 Percent Senior Notes due April 2021	Dec. 31, 2012 5.875 Percent Senior Notes due April 2021	Apr. 19, 2011 5.875 Percent Senior Notes due April 2021	Jun. 30, 2013 6.125 Percent Senior Notes due July 2022	Dec. 31, 2012 6.125 Percent Senior Notes due July 2022	Jan. 11, 2012 6.125 Percent Senior Notes due July 2022	Jun. 30, 2013 4.875 Percent Senior Notes due May 2023	Dec. 31, 2012 4.875 Percent Senior Notes due May 2023	Dec. 19, 2012 4.875 Percent Senior Notes due May 2023
Debt Instrument [Line Items]
Debt, interest rate	5.875%	5.875%	5.875%	6.125%	6.125%	6.125%	4.875%	4.875%	4.875%
Debt, maturity date	2021-04	2021-04		2022-07	2022-07		2023-05	2023-05

Interest rate stated in the contractual debt agreement.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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