Derivative Instruments - Summary of Customer-Related Derivative Positions of Company (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivative [Line Items]
Notional Value	$ 1,200,000
Customer-Related Positions [Member]
Derivative [Line Items]
Notional Value	1,118,589	$ 1,014,834
Fair Value, Assets	7,248	7,476
Fair Value, Liabilities	11,568	10,277
Customer-Related Positions [Member] | Interest Rate Contracts [Member] | Receive Fixed/Pay Floating Swaps [Member]
Derivative [Line Items]
Notional Value	354,783	301,690
Fair Value, Assets	146	309
Fair Value, Liabilities	7,358	5,689
Customer-Related Positions [Member] | Interest Rate Contracts [Member] | Pay Fixed/Receive Floating Swaps [Member]
Derivative [Line Items]
Notional Value	326,646	316,133
Fair Value, Assets	2,763	2,323
Fair Value, Liabilities	116	206
Customer-Related Positions [Member] | Interest Rate Contracts [Member] | Other Derivatives [Member]
Derivative [Line Items]
Notional Value	82,379	40,261
Fair Value, Assets	13	3
Fair Value, Liabilities	50	16
Customer-Related Positions [Member] | Interest Rate Contracts [Member] | Options [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value	112,927	103,489
Fair Value, Assets	1,583	1,794
Fair Value, Liabilities	0	5
Customer-Related Positions [Member] | Interest Rate Contracts [Member] | Options [Member] | Written [Member]
Derivative [Line Items]
Notional Value	107,595	99,923
Fair Value, Assets	1	6
Fair Value, Liabilities	1,622	1,779
Customer-Related Positions [Member] | Interest Rate Contracts [Member] | Futures [Member]
Derivative [Line Items]
Notional Value	0
Fair Value, Assets	0
Fair Value, Liabilities	0
Customer-Related Positions [Member] | Interest Rate Contracts [Member] | Futures [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value		3,623
Fair Value, Liabilities		4
Customer-Related Positions [Member] | Interest Rate Contracts [Member] | Futures [Member] | Written [Member]
Derivative [Line Items]
Notional Value	0	2,376
Fair Value, Assets	0	8
Fair Value, Liabilities	0
Customer-Related Positions [Member] | Foreign Exchange Rate Contracts [Member] | Forwards, Spots and Swaps [Member]
Derivative [Line Items]
Notional Value	114,004	134,666
Fair Value, Assets	2,523	3,010
Fair Value, Liabilities	2,202	2,548
Customer-Related Positions [Member] | Foreign Exchange Option [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value	806	954
Fair Value, Assets	29	22
Fair Value, Liabilities	0
Customer-Related Positions [Member] | Foreign Exchange Option [Member] | Written [Member]
Derivative [Line Items]
Notional Value	806	954
Fair Value, Assets	0
Fair Value, Liabilities	29	22
Customer-Related Positions [Member] | Commodity Contract [Member] | Swap [Member]
Derivative [Line Items]
Notional Value	2,063
Fair Value, Assets	61
Fair Value, Liabilities	56
Customer-Related Positions [Member] | Commodity Option [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value	2,811
Fair Value, Assets	128
Fair Value, Liabilities	128
Customer-Related Positions [Member] | Credit Contracts [Member]
Derivative [Line Items]
Notional Value	13,769	10,765
Fair Value, Assets	1	1
Fair Value, Liabilities	$ 7	$ 8