Partners' Capital - Additional Information (Detail) (Common Units [Member], USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended
Sep. 30, 2014	Mar. 31, 2014
Limited Partners' Capital Account [Line Items]
Units issued		4,172
Units issued	4,140,000
Average price of units	$ 33.99
Proceeds from offering and overallotment exercise, net of underwriters discount, structuring fee and related costs	$ 135.0
Dunne Manning Inc. (DMI) [Member]
Limited Partners' Capital Account [Line Items]
Units issued		92,683

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

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

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 272

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

Name:	us-gaap_PartnersCapitalAccountUnitsSaleOfUnits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration