Annual report pursuant to Section 13 and 15(d)

Debt - Additional Information (Detail)

v2.4.1.9
Debt - Additional Information (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended 0 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Nov. 01, 2014
Aug. 01, 2017
Aug. 01, 2016
Aug. 01, 2015
Jun. 24, 2013
Oct. 31, 2014
Jun. 03, 2013
Schedule Of Maturities Of Long Term Debt [Line Items]                    
Credit facility, proceeds from borrowings   $ 7,000us-gaap_ProceedsFromLinesOfCredit                
Borrowings under revolving credit facility 24us-gaap_LineOfCredit 3,000us-gaap_LineOfCredit                
Interest expense including amortization of deferred financing fees 381us-gaap_InterestExpense 447us-gaap_InterestExpense 304us-gaap_InterestExpense              
Promissory Note                    
Schedule Of Maturities Of Long Term Debt [Line Items]                    
Debt instrument spread on variable rate 1.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_LongtermDebtTypeAxis
= samg_PromissoryNotesPayableMember
                 
Debt instrument variable interest rate basis The principal amount outstanding under these notes bear interest at the U.S. Prime Rate plus 1% in effect at the time payments are due.                  
Aggregate principal amount                   5,300us-gaap_DebtInstrumentFaceAmount
/ us-gaap_LongtermDebtTypeAxis
= samg_PromissoryNotesPayableMember
Debt instrument reduction to principal amount                 1,722samg_DebtInstrumentReductionToPrincipalAmount
/ us-gaap_LongtermDebtTypeAxis
= samg_PromissoryNotesPayableMember
 
Principal amount of notes 3,578samg_DebtInstrumentAmountOutstanding
/ us-gaap_LongtermDebtTypeAxis
= samg_PromissoryNotesPayableMember
                 
Principal amount payment terms As a result, the principal amounts of the notes of $3,578 are payable in four equal installments of approximately $900 on November 1, 2014, and on each of August 1, 2015, 2016 and 2017.                  
Number of installments 4samg_DebtInstrumentNumberOfInstallment
/ us-gaap_LongtermDebtTypeAxis
= samg_PromissoryNotesPayableMember
                 
Installment amount payable       900us-gaap_DebtInstrumentPeriodicPaymentPrincipal
/ us-gaap_LongtermDebtTypeAxis
= samg_PromissoryNotesPayableMember
           
Principal amount of notes outstanding 2,683us-gaap_DebtInstrumentCarryingAmount
/ us-gaap_LongtermDebtTypeAxis
= samg_PromissoryNotesPayableMember
                 
Accrued, unpaid interest 19us-gaap_DebtInstrumentIncreaseAccruedInterest
/ us-gaap_LongtermDebtTypeAxis
= samg_PromissoryNotesPayableMember
                 
Scenario Forecast | Promissory Note                    
Schedule Of Maturities Of Long Term Debt [Line Items]                    
Installment amount payable         900us-gaap_DebtInstrumentPeriodicPaymentPrincipal
/ us-gaap_LongtermDebtTypeAxis
= samg_PromissoryNotesPayableMember
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember
900us-gaap_DebtInstrumentPeriodicPaymentPrincipal
/ us-gaap_LongtermDebtTypeAxis
= samg_PromissoryNotesPayableMember
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember
900us-gaap_DebtInstrumentPeriodicPaymentPrincipal
/ us-gaap_LongtermDebtTypeAxis
= samg_PromissoryNotesPayableMember
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember
     
City National Bank                    
Schedule Of Maturities Of Long Term Debt [Line Items]                    
Credit facility, borrowing capacity               15,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
   
Credit facility, proceeds from borrowings               7,000us-gaap_ProceedsFromLinesOfCredit
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
   
Borrowings under revolving credit facility 0us-gaap_LineOfCredit
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
3,000us-gaap_LineOfCredit
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
               
Interest expense including amortization of deferred financing fees 148us-gaap_InterestExpense
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
152us-gaap_InterestExpense
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
               
Interest on principal amount 3.75%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
3.30%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
               
Delayed Draw Term Loan | City National Bank                    
Schedule Of Maturities Of Long Term Debt [Line Items]                    
Credit facility, borrowing capacity               7,500us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_CreditFacilityAxis
= samg_DelayedDrawTermLoanMember
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
   
Credit facility maturity date               Jun. 24, 2020    
Credit facility, interest rate description The higher of the prime rate plus a margin of 0.05 percentage points and 2.5% or (b) the LIBOR rate plus 3 percentage points, at the borrowers’ option                  
Credit facility, number of installments               20samg_LineOfCreditFacilityNumberOfInstallments
/ us-gaap_CreditFacilityAxis
= samg_DelayedDrawTermLoanMember
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
   
Credit facility, frequency of installments Quarterly                  
Delayed Draw Term Loan | City National Bank | Option One | Maximum                    
Schedule Of Maturities Of Long Term Debt [Line Items]                    
Debt instrument spread on variable rate               0.05%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_CreditFacilityAxis
= samg_DelayedDrawTermLoanMember
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_StatementScenarioAxis
= samg_OptionOneMember
   
Debt instrument variable interest rate basis Prime rate                  
Delayed Draw Term Loan | City National Bank | Option One | Minimum                    
Schedule Of Maturities Of Long Term Debt [Line Items]                    
Credit facility, fixed interest rate               2.50%us-gaap_LineOfCreditFacilityInterestRateDuringPeriod
/ us-gaap_CreditFacilityAxis
= samg_DelayedDrawTermLoanMember
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_StatementScenarioAxis
= samg_OptionOneMember
   
Delayed Draw Term Loan | City National Bank | Option Two                    
Schedule Of Maturities Of Long Term Debt [Line Items]                    
Debt instrument spread on variable rate               3.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_CreditFacilityAxis
= samg_DelayedDrawTermLoanMember
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
/ us-gaap_StatementScenarioAxis
= samg_OptionTwoMember
   
Debt instrument variable interest rate basis LIBOR                  
Borrowings Under Revolving Credit Agreement | City National Bank                    
Schedule Of Maturities Of Long Term Debt [Line Items]                    
Credit facility, borrowing capacity               $ 7,500us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember
   
Credit facility maturity date               Dec. 24, 2016    
Debt covenant, restriction on change in control               30.00%samg_DebtCovenantRestrictionOnChangeInControl
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_LineOfCreditFacilityAxis
= samg_CityNationalBankMember