Summary of Significant Accounting Policies (Schedule of Weighted Average Number of Units) (Details) (Common Limited Partners [Member])	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Weighted average common limited partner units (basic)	64,646,000		53,620,000
Add effect of participating securities - phantom units	0	[1]	393,000	[1]
Weighted average common limited partner units (diluted)	64,646,000		54,013,000
Phantom Unit Awards [Member]
Antidilutive securities excluded from computation of earnings per unit	1,055,000

[1] For the three months ended March 31, 2013 approximately 1,055,000 phantom units were excluded from the computation of diluted earnings attributable to common limited partners per unit because the inclusion of such phantom units would have been anti-dilutive.