Open Oil and Natural Gas Commodity Derivative Contracts - Mississippian Trust I (Detail) (Sand Ridge Mississippian Trust I)	Dec. 31, 2011 Mbbl
Oil | Swap | January 2012 Through December 2012
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount (Oil in MBbl/ Natural Gas in MMBtu/ Diesel in Gallons)	454
Weighted Avg. Fixed Price (Oil in USD / bbl, Natural Gas in USD / btu, Diesel in USD / gal)	104.15
Oil | Swap | January 2013 Through December 2013
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount (Oil in MBbl/ Natural Gas in MMBtu/ Diesel in Gallons)	488
Weighted Avg. Fixed Price (Oil in USD / bbl, Natural Gas in USD / btu, Diesel in USD / gal)	102.07
Oil | Swap | January 2014 Through December 2014
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount (Oil in MBbl/ Natural Gas in MMBtu/ Diesel in Gallons)	541
Weighted Avg. Fixed Price (Oil in USD / bbl, Natural Gas in USD / btu, Diesel in USD / gal)	100.94
Oil | Swap | January 2015 Through December 2015
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount (Oil in MBbl/ Natural Gas in MMBtu/ Diesel in Gallons)	468
Weighted Avg. Fixed Price (Oil in USD / bbl, Natural Gas in USD / btu, Diesel in USD / gal)	101.07
Natural Gas | Swap | January 2012 Through June 2012
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount (Oil in MBbl/ Natural Gas in MMBtu/ Diesel in Gallons)	2,190
Weighted Avg. Fixed Price (Oil in USD / bbl, Natural Gas in USD / btu, Diesel in USD / gal)	4.90
Natural Gas | Collars | January 2013 Through December 2013
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount (Oil in MBbl/ Natural Gas in MMBtu/ Diesel in Gallons)	858
Collar Range, minimum	4.00
Collar Range, maximum	7.15
Natural Gas | Collars | January 2014 Through December 2014
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount (Oil in MBbl/ Natural Gas in MMBtu/ Diesel in Gallons)	937
Collar Range, minimum	4.00
Collar Range, maximum	7.78
Natural Gas | Collars | January 2015 Through December 2015
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount (Oil in MBbl/ Natural Gas in MMBtu/ Diesel in Gallons)	1,010
Collar Range, minimum	4.00
Collar Range, maximum	8.55
Natural Gas | Collars | July 2012 Through December 2012
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount (Oil in MBbl/ Natural Gas in MMBtu/ Diesel in Gallons)	402
Collar Range, minimum	4.00
Collar Range, maximum	6.20