Statements of Partners' Capital Parenthetical (USD $)	12 Months Ended
Dec. 31, 2012
Class A Units
Distributions of net sale proceeds (in dollars per unit)	$ 0.99
Class B Units
Distributions of net sale proceeds (in dollars per unit)	$ 1.11

Cash dividends declared or paid to each outstanding limited partnership unit during the reporting period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187171-122770

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 4

-Section F

Name:	us-gaap_DistributionsPerLimitedPartnershipUnitOutstanding
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration