XML 21 R42.htm IDEA: XBRL DOCUMENT v3.3.0.814

Pension Benefits Pension Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($)
Pension Narrative [Abstract]
Percentage in excess of the greater of the benefit obligation or the market-related value of assets, gain and losses amortized (as a percent)	10.00%
Pension and Other Postretirement Benefit Contributions	$ 6.4

X

- Definition

Pension Narrative [Abstract]

+ References

No definition available.

+ Details

Name:	sm_PensionNarrativeAbstract
Namespace Prefix:	sm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Pension and Other Post-retirement Benefit Plans, Gain (Loss) Amt Threshold

+ References

No definition available.

+ Details

Name:	sm_PensionandOtherPostretirementBenefitPlansGainLossAmtThreshold
Namespace Prefix:	sm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The amount of cash or cash equivalents contributed during the reporting period by the entity to fund its pension plans and its non-pension postretirement benefit plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 230



-SubTopic 10



-Section 45



-Paragraph 25



-Subparagraph (g)



-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3536-108585

+ Details

Name:	us-gaap_PensionAndOtherPostretirementBenefitContributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration