Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Credit Ratings of Credit Risk Related Guarantees (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Credit Derivatives [Line Items]
Credit derivatives, Notional/Maximum Exposure to Loss	$ 8,137	$ 10,726
Total, Notional/Maximum Exposure to Loss	12,427	12,097
Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit derivatives, Notional/Maximum Exposure to Loss	$ 3,900	$ 2,992
Single name credit default swaps | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Average Life (in years)	1 year 2 months 12 days
Credit derivatives, Notional/Maximum Exposure to Loss	$ 1,361
Index credit derivatives | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Average Life (in years)	4 years 6 months
Credit derivatives, Notional/Maximum Exposure to Loss	$ 2,539
Standby Letters of Credit
Credit Derivatives [Line Items]
Average Life (in years)	10 months 24 days
Standby letters of credit, Notional/Maximum Exposure to Loss	$ 8,527
Investment Grade
Credit Derivatives [Line Items]
Total, Notional/Maximum Exposure to Loss	9,099
Investment Grade | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit derivatives, Notional/Maximum Exposure to Loss	2,697
Investment Grade | Single name credit default swaps | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit derivatives, Notional/Maximum Exposure to Loss	873
Investment Grade | Index credit derivatives | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit derivatives, Notional/Maximum Exposure to Loss	1,824
Investment Grade | Standby Letters of Credit
Credit Derivatives [Line Items]
Standby letters of credit, Notional/Maximum Exposure to Loss	6,402
Non-Investment Grade
Credit Derivatives [Line Items]
Total, Notional/Maximum Exposure to Loss	3,328
Non-Investment Grade | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit derivatives, Notional/Maximum Exposure to Loss	1,203
Non-Investment Grade | Single name credit default swaps | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit derivatives, Notional/Maximum Exposure to Loss	488
Non-Investment Grade | Index credit derivatives | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit derivatives, Notional/Maximum Exposure to Loss	715
Non-Investment Grade | Standby Letters of Credit
Credit Derivatives [Line Items]
Standby letters of credit, Notional/Maximum Exposure to Loss	$ 2,125