Stockholders' Equity - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified
|
12 Months Ended |
0 Months Ended |
1 Months Ended |
3 Months Ended |
Dec. 31, 2014
|
Dec. 31, 2013
|
Dec. 31, 2012
|
Jul. 12, 2013
|
Jul. 02, 2013
|
May 31, 2014
|
Feb. 28, 2014
|
Dec. 31, 2014
|
Nov. 30, 2013
|
Dec. 31, 2014
|
Sep. 30, 2014
|
Class Of Stock [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
Partnership distributions, amount |
$ 5,242us-gaap_PartnersCapitalAccountDistributions
|
$ 29,317us-gaap_PartnersCapitalAccountDistributions
|
$ 14,749us-gaap_PartnersCapitalAccountDistributions
|
|
|
|
|
|
|
|
|
Amount distributed to existing partners |
10,000samg_ExistingPartnersCapitalAccountDistributions
|
|
|
|
|
|
|
|
|
|
|
Distributions of partner incentive allocations of net income |
14,266samg_DistributionsOfPartnerIncentiveAllocationsOfNetIncome
|
12,104samg_DistributionsOfPartnerIncentiveAllocationsOfNetIncome
|
8,775samg_DistributionsOfPartnerIncentiveAllocationsOfNetIncome
|
|
|
|
|
|
|
|
|
Accrued partner incentive allocations |
21,758us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent
|
17,424us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent
|
|
|
|
|
|
21,758us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent
|
|
21,758us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent
|
|
Class A Common Stock |
|
|
|
|
|
|
|
|
|
|
|
Class Of Stock [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
Common stock issued |
|
5,509,000us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember
|
|
718,603us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember
|
4,790,684us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember
|
|
|
|
|
|
|
Exchange of Class B common stock for Class A common stock |
246,000samg_StockIssuedDuringPeriodSharesConversionOfConvertibleShares / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember
|
2,013,000samg_StockIssuedDuringPeriodSharesConversionOfConvertibleShares / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember
|
|
|
|
|
|
|
|
|
|
Common stock, par value |
$ 0.01us-gaap_CommonStockParOrStatedValuePerShare / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember
|
$ 0.01us-gaap_CommonStockParOrStatedValuePerShare / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember
|
|
|
|
|
|
$ 0.01us-gaap_CommonStockParOrStatedValuePerShare / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember
|
|
0.01us-gaap_CommonStockParOrStatedValuePerShare / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember
|
|
Class B Common Stock |
|
|
|
|
|
|
|
|
|
|
|
Class Of Stock [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
Common stock issued |
261,958us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
|
|
|
|
261,958us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
|
|
|
Exchange of Class B common stock for Class A common stock |
(246,000)samg_StockIssuedDuringPeriodSharesConversionOfConvertibleShares / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
(2,013,677)samg_StockIssuedDuringPeriodSharesConversionOfConvertibleShares / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
|
|
|
|
|
|
|
|
Common stock repurchased/surrendered and cancelled |
16,530us-gaap_StockRepurchasedDuringPeriodShares / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
|
|
|
5,893us-gaap_StockRepurchasedDuringPeriodShares / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
16,530us-gaap_StockRepurchasedDuringPeriodShares / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
|
|
|
Common stock, par value |
$ 0.01us-gaap_CommonStockParOrStatedValuePerShare / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
$ 0.01us-gaap_CommonStockParOrStatedValuePerShare / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
|
|
$ 17.73us-gaap_CommonStockParOrStatedValuePerShare / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
$ 14.50us-gaap_CommonStockParOrStatedValuePerShare / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
$ 0.01us-gaap_CommonStockParOrStatedValuePerShare / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
0.01us-gaap_CommonStockParOrStatedValuePerShare / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
Common stock surrendered in settlement of an outstanding note receivable |
|
|
|
|
|
4,596us-gaap_DebtConversionConvertedInstrumentSharesIssued1 / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
|
|
|
|
Common stock surrendered in settlement of an outstanding note receivable, value |
|
|
|
|
|
81us-gaap_DebtConversionConvertedInstrumentAmount1 / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
|
|
|
|
Class B Common Stock | Limited Partners |
|
|
|
|
|
|
|
|
|
|
|
Class Of Stock [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
Common stock issued |
|
|
|
|
|
|
|
60,000us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_LimitedPartnerMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
|
|
Sale of common stock price per share |
$ 15.66us-gaap_SaleOfStockPricePerShare / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_LimitedPartnerMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
|
|
|
|
|
$ 15.66us-gaap_SaleOfStockPricePerShare / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_LimitedPartnerMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
15.66us-gaap_SaleOfStockPricePerShare / us-gaap_PartnerTypeOfPartnersCapitalAccountAxis = us-gaap_LimitedPartnerMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
Death of Chief Executive Officer | Class B Common Stock |
|
|
|
|
|
|
|
|
|
|
|
Class Of Stock [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
Exchange of Class B common stock for Class A common stock |
|
|
|
|
|
|
|
|
2,013,677samg_StockIssuedDuringPeriodSharesConversionOfConvertibleShares / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = us-gaap_ChiefExecutiveOfficerMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
|
|
Resale and Registration Rights Agreement | Class B Common Stock |
|
|
|
|
|
|
|
|
|
|
|
Class Of Stock [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
Exchange of Class B common stock for Class A common stock |
|
|
|
|
|
|
|
|
|
110,000samg_StockIssuedDuringPeriodSharesConversionOfConvertibleShares / us-gaap_ConversionOfStockByUniqueDescriptionAxis = samg_ResaleAndRegistrationRightsAgreementMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
133,739samg_StockIssuedDuringPeriodSharesConversionOfConvertibleShares / us-gaap_ConversionOfStockByUniqueDescriptionAxis = samg_ResaleAndRegistrationRightsAgreementMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassBMember
|
SLP |
|
|
|
|
|
|
|
|
|
|
|
Class Of Stock [Line Items] |
|
|
|
|
|
|
|
|
|
|
|
Accrued partner incentive allocations |
$ 18,653us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent / dei_LegalEntityAxis = samg_SlpMember
|
$ 14,196us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent / dei_LegalEntityAxis = samg_SlpMember
|
|
|
|
|
|
$ 18,653us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent / dei_LegalEntityAxis = samg_SlpMember
|
|
18,653us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent / dei_LegalEntityAxis = samg_SlpMember
|
|