Related Parties (Details)	6 Months Ended
	Jun. 30, 2012
For the first $500 million [Member]
Management fee according to fund's average daily net assets
Management Fee Percentage	1.25%
For the next $500 million [Member]
Management fee according to fund's average daily net assets
Management Fee Percentage	1.225%
For the next $500 million [Member]
Management fee according to fund's average daily net assets
Management Fee Percentage	1.20%
For the next $500 million [Member]
Management fee according to fund's average daily net assets
Management Fee Percentage	1.175%
For net assets over $2 billion [Member]
Management fee according to fund's average daily net assets
Management Fee Percentage	1.15%