Quarterly report pursuant to Section 13 or 15(d)

Notes Receivable from Partners - Schedule of Notes Receivable from Partners (Detail)

v2.4.1.9
Notes Receivable from Partners - Schedule of Notes Receivable from Partners (Detail) (Partners, USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Partners
   
Accounts Notes And Loans Receivable [Line Items]    
Beginning balance $ 3,212us-gaap_NotesReceivableNet
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= samg_GeneralPartnerAndLimitedPartnerMember
$ 3,052us-gaap_NotesReceivableNet
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= samg_GeneralPartnerAndLimitedPartnerMember
Repayment of notes (481)us-gaap_RepaymentOfNotesReceivableFromRelatedParties
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= samg_GeneralPartnerAndLimitedPartnerMember
(841)us-gaap_RepaymentOfNotesReceivableFromRelatedParties
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= samg_GeneralPartnerAndLimitedPartnerMember
Interest accrued and capitalized on notes receivable 18us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= samg_GeneralPartnerAndLimitedPartnerMember
61us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= samg_GeneralPartnerAndLimitedPartnerMember
New notes receivable issued to partners   940samg_NotesReceivableFromNewPartnersIssuedAsCapitalContribution
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= samg_GeneralPartnerAndLimitedPartnerMember
Ending balance $ 2,749us-gaap_NotesReceivableNet
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= samg_GeneralPartnerAndLimitedPartnerMember
$ 3,212us-gaap_NotesReceivableNet
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= samg_GeneralPartnerAndLimitedPartnerMember