v2.4.0.6
Risk - Additional Information (Detail)
3 Months Ended
Mar. 31, 2013
Unusual Risk or Uncertainty [Line Items]  
Percentage of calculation on simple inverse correlation 200.00%
UltraShort Fund [Member]
 
Unusual Risk or Uncertainty [Line Items]  
Leverage risk benchmark 50% at any point in the day
Swap agreements or forward contracts [Member]
 
Unusual Risk or Uncertainty [Line Items]  
Exposure to swap agreements or forward contracts 100.00%