XML 44 R32.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Long-Term Debt Senior Notes (Details) |  | 3 Months Ended | 6 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Jun. 30, 2017 USD ($) $ / shares | Jun. 30, 2017 USD ($) $ / shares | Jun. 30, 2016 USD ($) | Jun. 30, 2017 USD ($) $ / shares | Jun. 30, 2016 USD ($) | Mar. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Aug. 12, 2016 USD ($) | Mar. 31, 2016 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes, Noncurrent |  | $ 2,767,030,000 |  | $ 2,767,030,000 |  |  | $ 2,767,030,000 |  |  |  | $ 2,766,719,000 |  |  |
Gain (loss) on extinguishment of debt |  |  |  | 0 |  | $ 0 | (35,000) |  | $ 15,722,000 |  |  |  |  |
Gains (losses) on extinguishment of debt, noncash portion |  |  |  |  |  |  | (22,000) |  | 15,722,000 |  |  |  |  |
Convertible Debt, Noncurrent |  | $ 134,918,000 |  | $ 134,918,000 |  |  | $ 134,918,000 |  |  |  | 130,856,000 |  |  |
Capped Call, Cap Price | $ / shares |  | $ 60.00 |  | $ 60.00 |  |  | $ 60.00 |  |  |  |  |  |  |
6.50% Senior Notes Due 2021 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount | [1] | $ 344,611,000 |  | $ 344,611,000 |  |  | $ 344,611,000 |  |  |  |  |  |  |
Unamortized Debt Issuance Expense |  | (3,003,000) | [1] | (3,003,000) | [1] |  | (3,003,000) | [1] |  |  | (3,372,000) | [2] |  |
Senior Notes, Noncurrent |  | 341,608,000 | [1] | 341,608,000 | [1] |  | 341,608,000 | [1] |  |  | 343,583,000 | [2] |  |
6.125% Senior Notes Due 2022 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | 561,796,000 |  | 561,796,000 |  |  | 561,796,000 |  |  |  |  |  |  |
Unamortized Debt Issuance Expense |  | (6,390,000) |  | (6,390,000) |  |  | (6,390,000) |  |  |  | (6,979,000) | [2] |  |
Senior Notes, Noncurrent |  | 555,406,000 |  | 555,406,000 |  |  | 555,406,000 |  |  |  | 554,817,000 | [2] |  |
6.50% Senior Notes Due 2023 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | 394,985,000 |  | 394,985,000 |  |  | 394,985,000 |  |  |  |  |  |  |
Unamortized Debt Issuance Expense |  | (4,071,000) |  | (4,071,000) |  |  | (4,071,000) |  |  |  | (4,436,000) | [2] |  |
Senior Notes, Noncurrent |  | 390,914,000 |  | 390,914,000 |  |  | 390,914,000 |  |  |  | 390,549,000 | [2] |  |
5% Senior Notes Due 2024 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | 500,000,000 |  | 500,000,000 |  |  | 500,000,000 |  |  |  |  |  |  |
Unamortized Debt Issuance Expense |  | (6,072,000) |  | (6,072,000) |  |  | (6,072,000) |  |  |  | (6,533,000) |  |  |
Senior Notes, Noncurrent |  | 493,928,000 |  | 493,928,000 |  |  | 493,928,000 |  |  |  | 493,467,000 |  |  |
5.625% Senior Notes Due 2025 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | 500,000,000 |  | 500,000,000 |  |  | 500,000,000 |  |  |  |  |  |  |
Unamortized Debt Issuance Expense |  | (7,166,000) |  | (7,166,000) |  |  | (7,166,000) |  |  |  | (7,619,000) |  |  |
Senior Notes, Noncurrent |  | 492,834,000 |  | 492,834,000 |  |  | 492,834,000 |  |  |  | 492,381,000 |  |  |
6.75% Senior Notes Due 2026 [Domain] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | 500,000,000 |  | 500,000,000 |  |  | 500,000,000 |  |  |  |  |  |  |
Unamortized Debt Issuance Expense |  | (7,660,000) |  | (7,660,000) |  |  | (7,660,000) |  |  |  | (8,078,000) |  |  |
Senior Notes, Noncurrent |  | 492,340,000 |  | 492,340,000 |  |  | 492,340,000 |  |  |  | 491,922,000 |  |  |
Senior Notes [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | 2,801,392,000 |  | 2,801,392,000 |  |  | 2,801,392,000 |  |  |  | 2,803,736,000 |  |  |
Unamortized Debt Issuance Expense |  | (34,362,000) |  | (34,362,000) |  |  | (34,362,000) |  |  |  | (37,017,000) |  |  |
Senior Notes, Noncurrent |  | $ 2,767,030,000 |  | $ 2,767,030,000 |  |  | $ 2,767,030,000 |  |  |  | 2,766,719,000 |  |  |
Senior Notes [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Repurchased Face Amount |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 46,300,000
Debt Instrument, Repurchased Settlement Amount |  |  |  |  |  |  |  |  | 29,900,000 |  |  |  |  |
Gain (loss) on extinguishment of debt |  |  |  |  |  |  |  |  | 15,700,000 |  |  |  |  |
Debt Instrument, Repurchase Discount |  |  |  |  |  |  |  |  | 16,400,000 |  |  |  |  |
Gains (losses) on extinguishment of debt, noncash portion |  |  |  |  |  |  |  |  | $ (700,000) |  |  |  |  |
Senior Notes [Member] | 6.50% Senior Notes Due 2021 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 6.50% |  | 6.50% |  |  | 6.50% |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | $ 344,611,000 |  | $ 344,611,000 |  |  | $ 344,611,000 |  |  |  | 346,955,000 |  |  |
Debt Instrument, Repurchased Face Amount |  |  |  |  |  |  |  |  |  | $ 2,300,000 |  |  |  |
Senior Notes [Member] | 6.125% Senior Notes Due 2022 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 6.125% |  | 6.125% |  |  | 6.125% |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | $ 561,796,000 |  | $ 561,796,000 |  |  | $ 561,796,000 |  |  |  | 561,796,000 |  |  |
Senior Notes [Member] | 6.50% Senior Notes Due 2023 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 6.50% |  | 6.50% |  |  | 6.50% |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | $ 394,985,000 |  | $ 394,985,000 |  |  | $ 394,985,000 |  |  |  | 394,985,000 |  |  |
Senior Notes [Member] | 5% Senior Notes Due 2024 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 5.00% |  | 5.00% |  |  | 5.00% |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | $ 500,000,000 |  | $ 500,000,000 |  |  | $ 500,000,000 |  |  |  | 500,000,000 |  |  |
Senior Notes [Member] | 5.625% Senior Notes Due 2025 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 5.625% |  | 5.625% |  |  | 5.625% |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | $ 500,000,000 |  | $ 500,000,000 |  |  | $ 500,000,000 |  |  |  | 500,000,000 |  |  |
Senior Notes [Member] | 6.75% Senior Notes Due 2026 [Domain] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 6.75% |  | 6.75% |  |  | 6.75% |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | $ 500,000,000 |  | $ 500,000,000 |  |  | $ 500,000,000 |  |  |  | 500,000,000 |  |  |
Convertible Debt [Member] | 1.50% Senior Convertible Notes Due 2021 [Domain] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 1.50% |  | 1.50% |  |  | 1.50% |  |  |  |  |  |  |
Debt Instrument, Face Amount |  | $ 172,500,000 |  | $ 172,500,000 |  |  | $ 172,500,000 |  |  |  | 172,500,000 |  |  |
Unamortized Debt Issuance Expense |  | (3,669,000) |  | (3,669,000) |  |  | $ (3,669,000) |  |  |  | (4,131,000) |  |  |
Debt Instrument, Convertible, Conversion Ratio |  |  |  |  |  |  | 24.6914 |  |  |  |  |  |  |
Debt Instrument, Principal Amount of Note |  | $ 1,000 |  | $ 1,000 |  |  | $ 1,000 |  |  |  |  |  |  |
Debt Instrument, Convertible, Conversion Price | $ / shares |  | $ 40.50 |  | $ 40.50 |  |  | $ 40.50 |  |  |  |  |  |  |
Debt Instrument, Convertible, Initial Fair Value of Liability Component |  |  |  |  |  |  |  |  |  |  |  |  | $ 132,300,000 |
Debt Instrument, Convertible, Comparable Yield |  | 7.25% |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Convertible, Initial Value of Equity Component |  |  |  |  |  |  |  |  |  |  |  |  | $ 40,200,000 |
Interest Expense, Debt |  |  |  | $ 2,500,000 |  |  | $ 4,900,000 |  |  |  |  |  |  |
Debt Instrument, Unamortized Discount |  | $ (33,913,000) |  | (33,913,000) |  |  | (33,913,000) |  |  |  | (37,513,000) |  |  |
Convertible Debt, Noncurrent |  | $ 134,918,000 |  | $ 134,918,000 |  |  | $ 134,918,000 |  |  |  | $ 130,856,000 |  |  |
[1] | During the first quarter of 2017, the Company repurchased a total of $2.3 million in aggregate principal amount of 6.50% Senior Notes due 2021 in open market transactions at a slight premium. The Company canceled all of these repurchased Senior Notes upon cash settlement.
[2] | During the first quarter of 2016, the Company repurchased a total of $46.3 million in aggregate principal amount of certain of its Senior Notes in open market transactions for a settlement amount of $29.9 million, excluding interest. The Company recorded a net gain on extinguishment of debt of approximately $15.7 million for the six months ended June 30, 2016. This amount includes a gain of approximately $16.4 million associated with the discount realized upon repurchase, which was partially offset by approximately $0.7 million related to the acceleration of unamortized deferred financing costs. The Company canceled all of these repurchased Senior Notes upon cash settlement.

X
- Definition The cap rate on a capped call transaction. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract. + References No definition available. + Details
Name: | sm_CappedCallCapPrice
Namespace Prefix: | sm_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Debt Instrument, Convertible, Comparable Yield + References No definition available. + Details
Name: | sm_DebtInstrumentConvertibleComparableYield
Namespace Prefix: | sm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt Instrument, Convertible, Initial Fair Value of Liability Component + References No definition available. + Details
Name: | sm_DebtInstrumentConvertibleInitialFairValueofLiabilityComponent
Namespace Prefix: | sm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The initial amount of the equity component of convertible debt which may be settled in cash upon conversion. + References No definition available. + Details
Name: | sm_DebtInstrumentConvertibleInitialValueofEquityComponent
Namespace Prefix: | sm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Debt Instrument, Principal Amount of Note + References No definition available. + Details
Name: | sm_DebtInstrumentPrincipalAmountofNote
Namespace Prefix: | sm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Discount realized on debt instrument that was repurchased. + References No definition available. + Details
Name: | sm_DebtInstrumentRepurchaseDiscount
Namespace Prefix: | sm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Debt Instrument, Repurchased Settlement Amount + References No definition available. + Details
Name: | sm_DebtInstrumentRepurchasedSettlementAmount
Namespace Prefix: | sm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Gains (Losses) on Extinguishment of Debt, Non Cash Portion + References No definition available. + Details
Name: | sm_GainsLossesonExtinguishmentofDebtNonCashPortion
Namespace Prefix: | sm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Carrying amount of long-term convertible debt as of the balance sheet date, net of the amount due in the next twelve months or greater than the normal operating cycle, if longer. The debt is convertible into another form of financial instrument, typically the entity's common stock. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_ConvertibleDebtNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The price per share of the conversion feature embedded in the debt instrument. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031898-161870 + Details
Name: | us-gaap_DebtInstrumentConvertibleConversionPrice1
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Conversion Rate -URI http://asc.fasb.org/extlink&oid=6509012 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(5)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644 + Details
Name: | us-gaap_DebtInstrumentConvertibleConversionRatio1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face (par) amount of the original debt instrument that was repurchased. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRepurchasedFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, after accumulated amortization, of debt discount. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400 + Details
Name: | us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12317-112629 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12355-112629 + Details
Name: | us-gaap_GainsLossesOnExtinguishmentOfDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of the cost of borrowed funds accounted for as interest expense for debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
Name: | us-gaap_InterestExpenseDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_SeniorLongTermNotes
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_UnamortizedDebtIssuanceExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A650SeniorNotesDue2021Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A6.125SeniorNotesDue2022Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A650SeniorNotesDue2023Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A5SeniorNotesDue2024Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A5.625SeniorNotesDue2025Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A6.75SeniorNotesDue2026Domain
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=us-gaap_SeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_ConvertibleDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A1.50SeniorConvertibleNotesDue2021Domain
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |