Annual report pursuant to Section 13 and 15(d)

Acquisitions - Summary of Purchase Consideration (Detail)

v2.4.1.9
Acquisitions - Summary of Purchase Consideration (Detail) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended 0 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Mar. 28, 2013
Business Acquisition [Line Items]        
Cash paid on date of acquisition $ 1,805us-gaap_PaymentsToAcquireBusinessesGross $ 703us-gaap_PaymentsToAcquireBusinessesGross $ 720us-gaap_PaymentsToAcquireBusinessesGross  
MW Commodity Advisors, LLC        
Business Acquisition [Line Items]        
Units issued   132us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable
/ us-gaap_BusinessAcquisitionAxis
= samg_MwCommodityAdvisorsLlcMember 		   
Call rights option issued   15us-gaap_BusinessCombinationConsiderationTransferredOther1
/ us-gaap_BusinessAcquisitionAxis
= samg_MwCommodityAdvisorsLlcMember 		   
Total purchase consideration   147us-gaap_BusinessCombinationConsiderationTransferred1
/ us-gaap_BusinessAcquisitionAxis
= samg_MwCommodityAdvisorsLlcMember 		   
Ten-Sixty        
Business Acquisition [Line Items]        
Cash paid on date of acquisition   2,500us-gaap_PaymentsToAcquireBusinessesGross
/ us-gaap_BusinessAcquisitionAxis
= samg_TenSixtyAssetManagementLlcMember 		  2,500us-gaap_PaymentsToAcquireBusinessesGross
/ us-gaap_BusinessAcquisitionAxis
= samg_TenSixtyAssetManagementLlcMember
Note payable due to Ten-Sixty   1,592us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred
/ us-gaap_BusinessAcquisitionAxis
= samg_TenSixtyAssetManagementLlcMember 		   
Total purchase consideration   $ 4,092us-gaap_BusinessCombinationConsiderationTransferred1
/ us-gaap_BusinessAcquisitionAxis
= samg_TenSixtyAssetManagementLlcMember