XML 44 R56.htm IDEA: XBRL DOCUMENT v2.4.1.9
Derivative Financial Instruments (Details)
Dec. 31, 2014
bbl
Crude Oil [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 14,700,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 230,800,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
Natural Gas Liquids [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 781,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasLiquidsReservesMember
IF El Paso Permian [Member]  
Derivative Financial Instruments  
Index percent of natural gas fixed swaps 3.00%sm_IndexPercentOfNaturalGasFixedSwaps
/ us-gaap_DerivativeByNatureAxis
= sm_IfElPasoPermianMember
Index percent of natural gas collars 4.00%sm_IndexPercentOfNaturalGasCollars
/ us-gaap_DerivativeByNatureAxis
= sm_IfElPasoPermianMember
IF HSC [Member]  
Derivative Financial Instruments  
Index percent of natural gas fixed swaps 82.00%sm_IndexPercentOfNaturalGasFixedSwaps
/ us-gaap_DerivativeByNatureAxis
= sm_IfHscMember
Index percent of natural gas collars 80.00%sm_IndexPercentOfNaturalGasCollars
/ us-gaap_DerivativeByNatureAxis
= sm_IfHscMember
IF NGPL TXOK [Member]  
Derivative Financial Instruments  
Index percent of natural gas fixed swaps 1.00%sm_IndexPercentOfNaturalGasFixedSwaps
/ us-gaap_DerivativeByNatureAxis
= sm_IfNgplTxokMember
IF NNG Ventura [Member]  
Derivative Financial Instruments  
Index percent of natural gas fixed swaps 3.00%sm_IndexPercentOfNaturalGasFixedSwaps
/ us-gaap_DerivativeByNatureAxis
= sm_IfNngVenturaMember
Index percent of natural gas collars 8.00%sm_IndexPercentOfNaturalGasCollars
/ us-gaap_DerivativeByNatureAxis
= sm_IfNngVenturaMember
IF Enable East [Member]  
Derivative Financial Instruments  
Index percent of natural gas fixed swaps 11.00%sm_IndexPercentOfNaturalGasFixedSwaps
/ us-gaap_DerivativeByNatureAxis
= sm_IFEnableEastMember
Index percent of natural gas collars 8.00%sm_IndexPercentOfNaturalGasCollars
/ us-gaap_DerivativeByNatureAxis
= sm_IFEnableEastMember
OPIS Natural Gasoline Mt Belv Non TET [Member]  
Derivative Financial Instruments  
Index percent of NGL fixed swaps 28.00%sm_IndexPercentOfNglFixedSwaps
/ us-gaap_DerivativeByNatureAxis
= sm_OPISNaturalGasolineMtBelvNonTETMember
OPIS Propane Mt Belv TET [Member]  
Derivative Financial Instruments  
Index percent of NGL fixed swaps 72.00%sm_IndexPercentOfNglFixedSwaps
/ us-gaap_DerivativeByNatureAxis
= sm_OPISPropaneMtBelvTETMember
Swap [Member] | Crude Oil [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 11,311,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Swap [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 217,763,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Swap [Member] | Natural Gas Liquids [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 781,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasLiquidsReservesMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Collar [Member] | Crude Oil [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 3,366,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Collar [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 13,002,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
First Quarter of 2015 [Member] | Swap [Member] | Crude Oil [Member]  
Derivative Financial Instruments  
Weighted- Average Contract Price 91.96us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_FirstQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Portion of Future Oil and Gas Production Being Hedged 1,711,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_FirstQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
First Quarter of 2015 [Member] | Swap [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 23,548,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_FirstQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Weighted- Average Contract Price 4.22us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_FirstQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
First Quarter of 2015 [Member] | Swap [Member] | Natural Gas Liquids [Member]  
Derivative Financial Instruments  
Weighted- Average Contract Price 55.42us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasLiquidsReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_FirstQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Portion of Future Oil and Gas Production Being Hedged 781,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasLiquidsReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_FirstQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
First Quarter of 2015 [Member] | Collar [Member] | Crude Oil [Member]  
Derivative Financial Instruments  
Weighted- Average Floor Price 85.00us-gaap_DerivativeAverageFloorPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_FirstQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Weighted- Average Ceiling Price 99.53us-gaap_DerivativeAverageCapPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_FirstQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Portion of Future Oil and Gas Production Being Hedged 882,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_FirstQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
First Quarter of 2015 [Member] | Collar [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 2,524,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_FirstQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Weighted- Average Floor Price 4.00us-gaap_DerivativeAverageFloorPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_FirstQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Weighted- Average Ceiling Price 4.30us-gaap_DerivativeAverageCapPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_FirstQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Second Quarter of 2015 [Member] | Swap [Member] | Crude Oil [Member]  
Derivative Financial Instruments  
Weighted- Average Contract Price 91.26us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_SecondQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Portion of Future Oil and Gas Production Being Hedged 1,639,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_SecondQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Second Quarter of 2015 [Member] | Swap [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 15,985,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_SecondQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Weighted- Average Contract Price 3.90us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_SecondQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Second Quarter of 2015 [Member] | Collar [Member] | Crude Oil [Member]  
Derivative Financial Instruments  
Weighted- Average Floor Price 85.00us-gaap_DerivativeAverageFloorPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_SecondQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Weighted- Average Ceiling Price 94.06us-gaap_DerivativeAverageCapPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_SecondQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Portion of Future Oil and Gas Production Being Hedged 709,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_SecondQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Second Quarter of 2015 [Member] | Collar [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 2,297,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_SecondQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Weighted- Average Floor Price 4.00us-gaap_DerivativeAverageFloorPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_SecondQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Weighted- Average Ceiling Price 4.30us-gaap_DerivativeAverageCapPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_SecondQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Third Quarter of 2015 [Member] | Swap [Member] | Crude Oil [Member]  
Derivative Financial Instruments  
Weighted- Average Contract Price 90.78us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_ThirdQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Portion of Future Oil and Gas Production Being Hedged 1,254,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_ThirdQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Third Quarter of 2015 [Member] | Swap [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 14,950,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_ThirdQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Weighted- Average Contract Price 4.03us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_ThirdQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Third Quarter of 2015 [Member] | Collar [Member] | Crude Oil [Member]  
Derivative Financial Instruments  
Weighted- Average Floor Price 85.00us-gaap_DerivativeAverageFloorPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_ThirdQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Weighted- Average Ceiling Price 91.25us-gaap_DerivativeAverageCapPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_ThirdQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Portion of Future Oil and Gas Production Being Hedged 906,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_ThirdQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Third Quarter of 2015 [Member] | Collar [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 2,005,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_ThirdQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Weighted- Average Floor Price 4.00us-gaap_DerivativeAverageFloorPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_ThirdQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Weighted- Average Ceiling Price 4.30us-gaap_DerivativeAverageCapPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_ThirdQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Fourth Quarter of 2015 Member] | Swap [Member] | Crude Oil [Member]  
Derivative Financial Instruments  
Weighted- Average Contract Price 90.15us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_FourthQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Portion of Future Oil and Gas Production Being Hedged 1,137,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_FourthQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Fourth Quarter of 2015 Member] | Swap [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 13,570,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_FourthQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Weighted- Average Contract Price 4.02us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_FourthQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Fourth Quarter of 2015 Member] | Collar [Member] | Crude Oil [Member]  
Derivative Financial Instruments  
Weighted- Average Floor Price 85.00us-gaap_DerivativeAverageFloorPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_FourthQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Weighted- Average Ceiling Price 92.19us-gaap_DerivativeAverageCapPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_FourthQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Portion of Future Oil and Gas Production Being Hedged 869,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_FourthQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Fourth Quarter of 2015 Member] | Collar [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 6,176,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_FourthQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Weighted- Average Floor Price 3.97us-gaap_DerivativeAverageFloorPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_FourthQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
Weighted- Average Ceiling Price 4.30us-gaap_DerivativeAverageCapPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_FourthQuarterofSubsequentYearMember
/ us-gaap_DerivativeInstrumentRiskAxis
= sm_CollarMember
2016 [Member] | Swap [Member] | Crude Oil [Member]  
Derivative Financial Instruments  
Weighted- Average Contract Price 88.01us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_A2016Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Portion of Future Oil and Gas Production Being Hedged 5,570,000us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CrudeOilMember
/ sm_DerivativeContractPeriodAxis
= sm_A2016Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
2016 [Member] | Swap [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 48,896,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_A2016Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Weighted- Average Contract Price 4.12us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_A2016Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
2017 [Member] | Swap [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 37,414,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_A2017Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Weighted- Average Contract Price 4.16us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_A2017Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
2018 [Member] | Swap [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 35,241,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_A2018Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Weighted- Average Contract Price 4.21us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_A2018Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
2019 [Member] | Swap [Member] | Natural Gas [Member]  
Derivative Financial Instruments  
Portion of Future Oil and Gas Production Being Hedged 28,159,000sm_PortionOfGasProductionBeingHedged
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_A2019Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember
Weighted- Average Contract Price 4.28us-gaap_DerivativeSwapTypeAverageFixedPrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_NaturalGasReservesMember
/ sm_DerivativeContractPeriodAxis
= sm_A2019Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_SwapMember