Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Credit Ratings of Credit Risk Related Guarantees (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	$ 10,474	$ 28,045
Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	$ 2,174
Single name credit default swap | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Average Life (in years)	2 years 2 months 12 days
Credit Ratings of the Obligors	$ 1,719
Index credit derivatives | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Average Life (in years)	13 years 6 months
Credit Ratings of the Obligors	$ 455
Standby Letters of Credit
Credit Derivatives [Line Items]
Average Life (in years)	1 year 3 months 18 days
Credit Ratings of the Obligors	$ 8,300
Investment Grade
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	8,003
Investment Grade | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	1,525
Investment Grade | Single name credit default swap | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	1,125
Investment Grade | Index credit derivatives | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	400
Investment Grade | Standby Letters of Credit
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	6,478
Non-Investment Grade
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	2,471
Non-Investment Grade | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	649
Non-Investment Grade | Single name credit default swap | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	594
Non-Investment Grade | Index credit derivatives | Sell-protection Credit Derivatives
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	55
Non-Investment Grade | Standby Letters of Credit
Credit Derivatives [Line Items]
Credit Ratings of the Obligors	$ 1,822