UNIT-BASED COMPENSATION (Inputs Used in Option Pricing Method) (Details)
1 Months Ended
Jul. 31, 2010
DFW Net Profits Interests
Apr. 30, 2010
DFW Net Profits Interests
Sep. 30, 2009
DFW Net Profits Interests
Jan. 31, 2012
SMP Net Profits Interests
Oct. 31, 2011
SMP Net Profits Interests
Apr. 30, 2011
SMP Net Profits Interests
Apr. 30, 2010
SMP Net Profits Interests
Sep. 30, 2009
SMP Net Profits Interests
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Length of holding period restriction 3 years 5 months 5 days 3 years 9 months 4 years 3 months 2 years 11 months 5 days 3 years 2 months 16 days 4 years 9 months 3 years 9 months 4 years 3 months
Discount for lack of marketability (as a percent) 35.90% 30.90% 34.80% 24.00% 33.10% 29.60% 30.90% 34.80%
Volatility (as a percent) 53.70% 49.80% 52.50% 37.00% 49.30% 43.20% 49.80% 52.50%