Loans - Summary of Concentration of Secured and Unsecured Loans (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 181,515	$ 162,135
Loans at fair value	$ 8,250	$ 10,769
Concentration risk percentage	100.00%	100.00%
Corporate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 63,181	$ 55,927
Loans at fair value	$ 1,844	$ 2,492
Concentration risk percentage	100.00%	100.00%
Wealth management
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 50,101	$ 43,998
Loans at fair value	$ 4,537	$ 5,936
Concentration risk percentage	100.00%	100.00%
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 26,082	$ 25,883
Loans at fair value	$ 1,277	$ 1,588
Concentration risk percentage	100.00%	100.00%
Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 14,342	$ 15,913
Loans at fair value	$ 257	$ 320
Concentration risk percentage	100.00%	100.00%
Installment
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 5,157	$ 3,672
Concentration risk percentage	100.00%	100.00%
Credit cards
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 13,691	$ 8,212
Concentration risk percentage	100.00%	100.00%
Other
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 8,961	$ 8,530
Loans at fair value	$ 335	$ 433
Concentration risk percentage	100.00%	100.00%
Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 181,515	$ 162,135
Internally rated loans | Corporate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	63,181	55,927
Internally rated loans | Wealth management
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	50,101	43,998
Internally rated loans | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	26,082	25,883
Internally rated loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	14,342	15,913
Internally rated loans | Installment
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	5,157	3,672
Internally rated loans | Credit cards
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	13,691	8,212
Internally rated loans | Other
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	8,961	8,530
Amortized Cost
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	166,465	143,507
Amortized Cost | Corporate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	57,431	50,960
Amortized Cost | Wealth management
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	45,564	38,062
Amortized Cost | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	22,214	21,150
Amortized Cost | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	14,084	15,493
Amortized Cost | Credit cards
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	13,691	8,212
Amortized Cost | Other
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	8,324	5,958
Amortized Cost | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	166,465	143,507
Fair Value
Financing Receivable, Recorded Investment [Line Items]
Loans at fair value	8,250	10,769
Fair Value | Corporate
Financing Receivable, Recorded Investment [Line Items]
Loans at fair value	1,844	2,492
Fair Value | Wealth management
Financing Receivable, Recorded Investment [Line Items]
Loans at fair value	4,537	5,936
Fair Value | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans at fair value	1,277	1,588
Fair Value | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans at fair value	257	320
Fair Value | Credit cards
Financing Receivable, Recorded Investment [Line Items]
Loans at fair value	0	0
Fair Value | Other
Financing Receivable, Recorded Investment [Line Items]
Loans at fair value	335	433
Fair Value | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Loans at fair value	8,250	10,769
Held For Sale
Financing Receivable, Recorded Investment [Line Items]
Loans held for sale	6,800	7,859
Held For Sale | Corporate
Financing Receivable, Recorded Investment [Line Items]
Loans held for sale	3,906	2,475
Held For Sale | Wealth management
Financing Receivable, Recorded Investment [Line Items]
Loans held for sale	0	0
Held For Sale | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans held for sale	2,591	3,145
Held For Sale | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans held for sale	1	100
Held For Sale | Credit cards
Financing Receivable, Recorded Investment [Line Items]
Loans held for sale	0	0
Held For Sale | Other
Financing Receivable, Recorded Investment [Line Items]
Loans held for sale	302	2,139
Held For Sale | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Loans held for sale	$ 6,800	$ 7,859
Loans Receivable | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Concentration risk percentage	100.00%	100.00%
Loans Receivable | Secured | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Concentration risk percentage	80.00%	82.00%
Loans Receivable | Unsecured | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Concentration risk percentage	20.00%	18.00%
Loans Receivable | Investment-Grade | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 65,156	$ 54,874
Concentration risk percentage	100.00%	100.00%
Loans Receivable | Investment-Grade | Internally rated loans | Corporate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 21,072	$ 15,370
Loans Receivable | Investment-Grade | Internally rated loans | Wealth management
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	36,376	31,476
Loans Receivable | Investment-Grade | Internally rated loans | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	2,586	3,986
Loans Receivable | Investment-Grade | Internally rated loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	935	1,112
Loans Receivable | Investment-Grade | Internally rated loans | Installment
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	0	0
Loans Receivable | Investment-Grade | Internally rated loans | Credit cards
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	0	0
Loans Receivable | Investment-Grade | Internally rated loans | Other
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 4,187	$ 2,930
Loans Receivable | Investment-Grade | Secured | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Concentration risk percentage	85.00%	85.00%
Loans Receivable | Investment-Grade | Unsecured | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Concentration risk percentage	15.00%	15.00%
Loans Receivable | Investment-Grade | Amortized Cost | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 62,336	$ 50,923
Loans Receivable | Investment-Grade | Fair Value | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Loans at fair value	1,784	2,301
Loans Receivable | Investment-Grade | Held For Sale | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Loans held for sale	1,036	1,650
Loans Receivable | Non-Investment- Grade | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 87,521	$ 84,560
Concentration risk percentage	100.00%	100.00%
Loans Receivable | Non-Investment- Grade | Internally rated loans | Corporate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 42,033	$ 40,389
Loans Receivable | Non-Investment- Grade | Internally rated loans | Wealth management
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	6,090	5,730
Loans Receivable | Non-Investment- Grade | Internally rated loans | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	23,246	21,523
Loans Receivable | Non-Investment- Grade | Internally rated loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	12,406	13,779
Loans Receivable | Non-Investment- Grade | Internally rated loans | Installment
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	0	0
Loans Receivable | Non-Investment- Grade | Internally rated loans | Credit cards
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	0	0
Loans Receivable | Non-Investment- Grade | Internally rated loans | Other
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 3,746	$ 3,139
Loans Receivable | Non-Investment- Grade | Secured | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Concentration risk percentage	93.00%	92.00%
Loans Receivable | Non-Investment- Grade | Unsecured | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Concentration risk percentage	7.00%	8.00%
Loans Receivable | Non-Investment- Grade | Amortized Cost | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 78,212	$ 75,179
Loans Receivable | Non-Investment- Grade | Fair Value | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Loans at fair value	3,606	4,634
Loans Receivable | Non-Investment- Grade | Held For Sale | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Loans held for sale	5,703	4,747
Loans Receivable | Other Metrics/Unrated | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 28,838	$ 22,701
Concentration risk percentage	100.00%	100.00%
Loans Receivable | Other Metrics/Unrated | Internally rated loans | Corporate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 76	$ 168
Loans Receivable | Other Metrics/Unrated | Internally rated loans | Wealth management
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	7,635	6,792
Loans Receivable | Other Metrics/Unrated | Internally rated loans | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	250	374
Loans Receivable | Other Metrics/Unrated | Internally rated loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	1,001	1,022
Loans Receivable | Other Metrics/Unrated | Internally rated loans | Installment
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	5,157	3,672
Loans Receivable | Other Metrics/Unrated | Internally rated loans | Credit cards
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	13,691	8,212
Loans Receivable | Other Metrics/Unrated | Internally rated loans | Other
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 1,028	$ 2,461
Loans Receivable | Other Metrics/Unrated | Secured | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Concentration risk percentage	31.00%	36.00%
Loans Receivable | Other Metrics/Unrated | Unsecured | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Concentration risk percentage	69.00%	64.00%
Loans Receivable | Other Metrics/Unrated | Amortized Cost | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross	$ 25,917	$ 17,405
Loans Receivable | Other Metrics/Unrated | Fair Value | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Loans at fair value	2,860	3,834
Loans Receivable | Other Metrics/Unrated | Held For Sale | Internally rated loans
Financing Receivable, Recorded Investment [Line Items]
Loans held for sale	$ 61	$ 1,462