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Borrowings - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended
	Mar. 31, 2024	Feb. 29, 2024	Oct. 31, 2023	Jan. 31, 2023	Jun. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Short-term borrowings					$ 4,764	$ 5,316
FHLB advances					2,005	5
Senior notes					3,743	3,741
Asset-backed notes					822	474
Long-term borrowings					11,319	$ 8,201
Secured Debt
Debt Instrument [Line Items]
Asset-backed notes	$ 526				457
Long-term debt term (in years)	2 years
Weighted average interest rate	5.29%
Secured Debt \| Third Party Investors
Debt Instrument [Line Items]
Asset-backed notes	$ 511				446
FHLB of New York
Debt Instrument [Line Items]
FHLB advances		$ 2,000
Variable interest rate of debt instrument		25.00%
Available line of credit					15,200
FRB of New York
Debt Instrument [Line Items]
Available line of credit					$ 21,500
5.053% Fixed Rate Senior Notes Due to Mature in January 2034
Debt Instrument [Line Items]
Variable interest rate of debt instrument	2.26%
Senior notes	$ 850
Interest rate of debt instrument	6.082%
Senior notes maturity date				Jan. 31, 2034
4.65% Fixed Rate Senior Notes Due to Mature in January 2026
Debt Instrument [Line Items]
Senior notes maturity date				Jan. 31, 2026
4.70% Fixed Rate Senior Notes Due to Mature in January 2028
Debt Instrument [Line Items]
Senior notes maturity date				Jan. 31, 2028
7.41% Fixed Rate Senior Notes Due to Mature in October 2029
Debt Instrument [Line Items]
Senior notes maturity date			Jan. 31, 2034