Debt Instrument, Convertible, Initial Fair Value of Liability Component

No definition available.

Name:	sm_DebtInstrumentConvertibleInitialFairValueofLiabilityComponent
Namespace Prefix:	sm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

- Definition

Debt Instrument, Senior Notes, Initial Fair Value

+ References

No definition available.

+ Details

Name:	sm_DebtInstrumentSeniorNotesInitialFairValue
Namespace Prefix:	sm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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

- Definition

Amount, after accumulated amortization, of debt discount.

+ References

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

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Name:	us-gaap_DeferredFinanceCostsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt.

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+ Details

Name:	us-gaap_InterestExpenseDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying amount of collateralized debt obligations with maturities initially due after one year or beyond the operating cycle, if longer, excluding the current portion. Obligations include, but not limited to, mortgage loans, chattel loans, and other borrowings secured by assets.

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

No definition available.

+ Details

Name:	us-gaap_UnamortizedDebtIssuanceExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=sm_A100SeniorSecuredNotesDue2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=sm_A150SeniorUnsecuredConvertibleNotesDue2021Member
Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Period Type:

Senior Secured Notes (Details) - USD ($) $ in Thousands		12 Months Ended
Senior Secured Notes (Details) - USD ($) $ in Thousands	Aug. 12, 2016	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022	Jun. 17, 2020
10.0% Senior Secured Notes due 2025
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage		10.00%		10.00%	10.00%
Senior Notes, Principal amount		$ 446,675		$ 0	$ 446,700
Senior Secured Notes, unamortized debt discount		30,236
Senior Notes, unamortized deferred financing costs		8,727
Secured Long-term Debt, Noncurrent		$ 407,712		$ 0
Senior Notes Debt Issuance Costs					13,100
Senior Notes, Initial Fair Value					$ 405,000
1.50% Senior Unsecured Convertible Notes Due 2021
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage	1.50%
Senior Notes, Principal amount	$ 172,500
Senior Notes Debt Issuance Costs	5,900
Net proceeds from Convertible Notes Issuance	166,600
Senior Unsecured Convertible Notes, Initial fair value of liability component	132,300
Senior Unsecured Convertible Notes, Initial value of equity component	$ 40,200
1.50% Senior Secured Convertible Notes Due 2021
Senior Notes [Line Items]
Senior Notes, interest rate, stated percentage		1.50%		1.50%
Senior Convertible Notes, interest expense		$ 2,300	$ 7,700