Partners' Equity, Allocations of Net Income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Partners' Capital [Abstract]
General partner interest in net income	$ 1,446	$ 1,059	$ 1,464
General partner incentive distribution	33,221	26,464	20,986
Total general partner interest in net income	$ 34,667	$ 27,523	$ 22,450

Amount of incentive obligation paid in cash or stock during the period to a limited liability corporation managing member or limited partnership general partner.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

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Amount of cash or stock or unit payment to a limited liability corporation managing member or limited partnership general partner after the end of the accounting period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

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Aggregate amount of net income allocated to general partners.

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

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-Name Accounting Standards Codification

-Topic 505

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

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