Unsecured Borrowings - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Subordinated debt maturities, range, end	Dec. 31, 2067
Minimum redemption or purchase price required	$ 253.0
Debt Instrument, Maturity Date Range, End	Dec. 31, 2067
Subordinated Debt [Member]
Debt Instrument [Line Items]
Subordinated debt maturities, range, start	Dec. 31, 2021	Dec. 31, 2021
Subordinated debt maturities, range, end	Dec. 31, 2045	Dec. 31, 2045
Trust Preferred Securities purchased, par amount	$ 164.0	$ 29.0	$ 192.0
Trust Preferred Securities purchased, carrying value	$ 231.0	$ 36.0	254.0
Debt Instrument, Maturity Date Range, End	Dec. 31, 2045	Dec. 31, 2045
Goldman Sachs Capital I [Member]
Debt Instrument [Line Items]
Junior subordinated debentures issued to Goldman Sachs Capital I (Trust)	$ 2,840.0
Guaranteed preferred beneficial interests issued to third parties	2,750.0
Common beneficial interests issued to Group Inc.	85.0
Junior subordinated debt, outstanding par amount	976.0	$ 1,140.0
Trust Preferred Securities, outstanding par amount	947.0	1,110.0
Common beneficial interests, outstanding par amount	29.0	34.1
Trust Preferred Securities purchased, par amount	159.0	28.0	186.0
Trust Preferred Securities purchased, carrying value	206.0	35.0	237.0
Common beneficial interests delivered to the Trust	$ 5.0	$ 1.0	$ 6.0
Interest Rate of Junior Subordinated Debentures held by certain third parties	6.345%
Maturity date of Junior Subordinated Debentures held by certain third parties	Feb. 15, 2034
Interest Rate of Junior Subordinated Debentures issued to Trust, Fixed	6.345%
Maturity date of Junior Subordinated Debentures issued to Trust	Feb. 15, 2034