Financial Instruments (Details) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Investment Holdings [Line Items]
Net unrealized gains on open contracts	$ 7,391,484	$ 6,652,432
Cash held by acting commodity futures brokers administrating open contracts	116,841,421	150,597,920
Exchange-Traded [Member]
Investment Holdings [Line Items]
Net unrealized gains on open contracts	6,364,616	6,193,496
Longest maturity date	Dec. 31, 2018	Dec. 31, 2017
Off-Exchange-Traded [Member]
Investment Holdings [Line Items]
Net unrealized gains on open contracts	$ 1,026,868	$ 458,936
Longest maturity date	Jan. 31, 2015	Mar. 31, 2014