XML 46 R1.htm IDEA: XBRL DOCUMENT v3.3.0.814
Document and Entity Information Document - shares
 9 Months Ended
Sep. 30, 2015
Oct. 21, 2015
Entity Information [Line Items]    
Entity Registrant Name SM Energy Co  
Entity Central Index Key 0000893538  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Document Type 10-Q  
Document Period End Date Sep. 30, 2015  
Document Fiscal Year Focus 2015  
Document Fiscal Period Focus Q3  
Amendment Flag false  
Entity Common Stock, Shares Outstanding   67,974,771
Entity Current Reporting Status Yes