Derivatives and Hedging Activities - Credit Derivatives (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	$ 565,328	$ 528,310
Offsetting
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	467,620	432,083
Other
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	164,788	147,061
Less than 1 Year
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	142,339	126,883
1 - 5 Years
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	343,259	357,488
Greater than 5 Years
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	79,730	43,939
Written Credit Derivative
Derivative [Line Items]
Fair Value Asset of Written Credit Derivatives	9,722	6,081
Fair Value Liability of Written Credit Derivatives	4,909	5,462
Fair Value Net Asset/(Liability) of Written Credit Derivatives	4,813	619
0 - 250
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	505,889	454,489
0 - 250 | Offsetting
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	420,373	372,360
0 - 250 | Other
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	152,511	128,828
0 - 250 | Less than 1 Year
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	127,828	108,703
0 - 250 | 1 - 5 Years
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	308,826	306,484
0 - 250 | Greater than 5 Years
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	69,235	39,302
0 - 250 | Written Credit Derivative
Derivative [Line Items]
Fair Value Asset of Written Credit Derivatives	8,701	5,405
Fair Value Liability of Written Credit Derivatives	1,190	681
Fair Value Net Asset/(Liability) of Written Credit Derivatives	7,511	4,724
251 - 500
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	34,990	43,270
251 - 500 | Offsetting
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	25,763	33,149
251 - 500 | Other
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	8,037	13,211
251 - 500 | Less than 1 Year
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	9,876	12,166
251 - 500 | 1 - 5 Years
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	18,554	28,188
251 - 500 | Greater than 5 Years
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	6,560	2,916
251 - 500 | Written Credit Derivative
Derivative [Line Items]
Fair Value Asset of Written Credit Derivatives	638	460
Fair Value Liability of Written Credit Derivatives	774	1,081
Fair Value Net Asset/(Liability) of Written Credit Derivatives	(136)	(621)
501 - 1,000
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	12,725	17,019
501 - 1,000 | Offsetting
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	11,309	14,817
501 - 1,000 | Other
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	2,189	2,615
501 - 1,000 | Less than 1 Year
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	885	1,879
501 - 1,000 | 1 - 5 Years
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	8,957	13,724
501 - 1,000 | Greater than 5 Years
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	2,883	1,416
501 - 1,000 | Written Credit Derivative
Derivative [Line Items]
Fair Value Asset of Written Credit Derivatives	262	132
Fair Value Liability of Written Credit Derivatives	633	1,027
Fair Value Net Asset/(Liability) of Written Credit Derivatives	(371)	(895)
Greater than 1,000
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	11,724	13,532
Greater than 1,000 | Offsetting
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	10,175	11,757
Greater than 1,000 | Other
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	2,051	2,407
Greater than 1,000 | Less than 1 Year
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	3,750	4,135
Greater than 1,000 | 1 - 5 Years
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	6,922	9,092
Greater than 1,000 | Greater than 5 Years
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivatives by Tenor	1,052	305
Greater than 1,000 | Written Credit Derivative
Derivative [Line Items]
Fair Value Asset of Written Credit Derivatives	121	84
Fair Value Liability of Written Credit Derivatives	2,312	2,673
Fair Value Net Asset/(Liability) of Written Credit Derivatives	$ (2,191)	$ (2,589)