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, 2022	Dec. 31, 2021
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	$ 14,683	$ 10,474
Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	$ 6,319
Single name credit default swap | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Average Life (in years)	1 year 10 months 24 days
Credit Ratings of the Obligors	$ 1,711
Index credit derivatives | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Average Life (in years)	5 years 7 months 6 days
Credit Ratings of the Obligors	$ 4,608
Standby Letters of Credit
Credit Derivatives [Line Items]
Average Life (in years)	1 year 2 months 12 days
Credit Ratings of the Obligors	$ 8,364
Investment Grade
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	11,126
Investment Grade | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	4,548
Investment Grade | Single name credit default swap | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	1,065
Investment Grade | Index credit derivatives | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	3,483
Investment Grade | Standby Letters of Credit
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	6,578
Non-Investment Grade
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	3,557
Non-Investment Grade | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	1,771
Non-Investment Grade | Single name credit default swap | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	646
Non-Investment Grade | Index credit derivatives | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	1,125
Non-Investment Grade | Standby Letters of Credit
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	$ 1,786