Silvercrest Asset Management Group LLC Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Acquisitions - Additional Information (Detail)

Acquisitions - Additional Information (Detail) - USD ($)						1 Months Ended		3 Months Ended				9 Months Ended		12 Months Ended
	Jul. 01, 2019	Apr. 12, 2019	Dec. 13, 2018	Dec. 15, 2015	Mar. 30, 2015	Aug. 31, 2019	May 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Revenue								$ 27,845,000		$ 24,932,000		$ 74,314,000	$ 73,840,000
Income before provision for income taxes								$ 6,324,000		$ 5,206,000		14,901,000	$ 16,071,000
Class B Common Stock
Business Acquisition [Line Items]
Issuance of Class B shares, Shares						241,624	948	663,000	2,000		6,000
Cortina Asset Management, LLC
Business Acquisition [Line Items]
Aggregate purchase amount												57,824,000
Equity consideration for SLP acquired								$ 13,800,000				13,800,000
Revenue								3,182,000				3,182,000
Income before provision for income taxes								976,000				976,000
Cash paid on date of acquisition												35,169,000
Cash paid on date of acquisition												17,072,000
Cortina Asset Management, LLC \| General, Administrative and Other
Business Acquisition [Line Items]
Costs related to acquisition												1,147,000
Cortina Asset Management, LLC \| Purchase Agreement
Business Acquisition [Line Items]
Aggregate purchase amount	$ 33,577,000
Percentage to acquire business in cash		80.00%
Additional percentage to acquire business in cash	80.00%	80.00%
Business combination consideration partially offset by net closing credits	$ 35,072,000
Equity consideration for SLP acquired	13,800,000
Business combination acquired revenue		$ 13,027,000
Cortina Asset Management, LLC \| Purchase Agreement \| Revenue Greater than or Equal to 95% for July 1, 2020 to June 30, 2021
Business Acquisition [Line Items]
Business combination contingent consideration first retention payment		3,370,000
Cortina Asset Management, LLC \| Purchase Agreement \| Revenue Equal to 75% or Less for July 1, 2020 to June 30, 2021
Business Acquisition [Line Items]
Business combination contingent consideration first retention payment		0
Cortina Asset Management, LLC \| Purchase Agreement \| Revenue Between 75% and 95% for July 1, 2020 to June 30, 2021
Business Acquisition [Line Items]
Business combination contingent consideration first retention payment, minimum		0
Business combination contingent consideration first retention payment, maximum		3,370,000
Cortina Asset Management, LLC \| Purchase Agreement \| Revenue Between 85% and 105% for July 1, 2021 to June 30, 2022
Business Acquisition [Line Items]
Business combination contingent consideration second retention payment, minimum		0
Business combination contingent consideration second retention payment, maximum		5,617,000
Cortina Asset Management, LLC \| Purchase Agreement \| Revenue Equal to 85% or Less for July 1, 2021 to June 30, 2022
Business Acquisition [Line Items]
Business combination contingent consideration second retention payment		0
Cortina Asset Management, LLC \| Purchase Agreement \| Revenue Between 95% and 140% for July 1, 2022 to June 30, 2023
Business Acquisition [Line Items]
Business combination contingent consideration growth payment, minimum		0
Business combination contingent consideration growth payment, maximum		17,222,000
Cortina Asset Management, LLC \| Purchase Agreement \| Revenue Equal to 95% or Less for July 1, 2022 to June 30, 2023
Business Acquisition [Line Items]
Business combination contingent consideration growth payment		0
Cortina Asset Management, LLC \| Purchase Agreement \| Maximum
Business Acquisition [Line Items]
Aggregate purchase amount		44,937,000
Additional aggregate purchase amount	26,209,000	26,209,000
Cortina Asset Management, LLC \| Purchase Agreement \| Maximum \| Revenue Between 85% and 105% for July 1, 2021 to June 30, 2022
Business Acquisition [Line Items]
Business combination contingent consideration second retention payment		5,617,000
Cortina Asset Management, LLC \| Purchase Agreement \| Maximum \| Revenue Between 95% and 140% for July 1, 2022 to June 30, 2023
Business Acquisition [Line Items]
Business combination contingent consideration growth payment		$ 17,222,000
Cortina Asset Management, LLC \| Purchase Agreement \| SLP
Business Acquisition [Line Items]
Percentage of business combination consideration issuance		20.00%
Additional aggregate purchase amount	$ 8,952,000
Additional percentage of earn out payment paid in cash	20.00%	20.00%
Potential earn-out payments period	4 years	4 years
Cortina Asset Management, LLC \| Purchase Agreement \| SLP \| Class B Common Stock
Business Acquisition [Line Items]
Issuance of Class B shares, Shares	662,713
Neosho
Business Acquisition [Line Items]
Equity consideration for SLP acquired			$ 20,000					1,686,000				1,686,000
Cash paid on date of acquisition			399,000									399,000
Contingent consideration			1,686,000
Expected payments on first anniversary of closing date			300,000
Earn out payments due in two years			100,000
Earn out payments due in three years			100,000
Earn out payments due in four years			100,000
Earn out payments due in five years			$ 100,000
Percentage of product to obtain earn out payment			50.00%
Percentage of earn out payment paid in cash			75.00%
Percentage of earn out payment paid in equity			25.00%
Cappiccille
Business Acquisition [Line Items]
Equity consideration for SLP acquired								$ 126,000				126,000		$ 231,000
Contingent consideration				$ 354,000
Cash paid on date of acquisition				$ 148,000
Earn out payments percentage on revenue remainder of fiscal year				19.00%
Earn out payments percentage on revenue due in two years				19.00%
Earn out payments percentage on revenue due in three years				19.00%
Earn out payments percentage on revenue due in four years				19.00%
Earn out payments percentage on revenue due thereafter				19.00%
Jamison
Business Acquisition [Line Items]
Equity consideration for SLP acquired					$ 3,562,000
Contingent consideration					1,429,000							$ 204,000		$ 524,000
Cash paid on date of acquisition					$ 3,550,000
Earn out payments percentage on EBITDA remainder of fiscal year					20.00%
Earn out payments percentage on EBITDA due in two years					20.00%
Earn out payments percentage on EBITDA due in three years					20.00%
Earn out payments percentage on EBITDA due in four years					20.00%
Earn out payments percentage on EBITDA due in five years					20.00%
Earn Out Payments Percentage On EBITDA Due thereafter					20.00%
Jamison \| Seller Note
Business Acquisition [Line Items]
Promissory note issued					$ 394,000
Interest on principal amount					5.00%
Jamison \| Principals Notes
Business Acquisition [Line Items]
Promissory note issued					$ 1,771,000
Interest on principal amount					5.00%