v3.20.4
Regulation and Capital Adequacy - CET1, Tier 1 Capital and Tier 2 Capital (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Change in allowance for credit losses $ (2,630) $ (450)
Standardized Capital Rules [Member]    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
CET 1, Beginning balance 74,850 73,116
Change in Impact of CECL transition 1,126  
Change in common shareholders' equity 5,667 80
Change in deduction for goodwill (123) (432)
Change in deduction for identifiable intangible assets 3 (307)
Change in other adjustments 118 2,393
CET 1, Ending balance 81,641 74,850
Tier 1 Capital, Beginning balance 85,440 83,702
Change in CET1 6,791 1,734
Change in deduction for investments in covered funds 504 5
Change in other adjustments (5) (1)
Tier 1 Capital, Ending balance 92,730 85,440
Tier 2 capital, Beginning balance 14,925 14,926
Change in qualifying subordinated debt (651) (300)
Change in junior subordinated debt (96) (158)
Change in allowance for credit losses 1,293 449
Change in other adjustments (47) 8
Tier 2 Capital, Ending balance 15,424 14,925
Total capital 108,154 100,365
Advanced Capital Rules [Member]    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
CET 1, Beginning balance 74,850 73,116
Change in Impact of CECL transition 1,126  
Change in common shareholders' equity 5,667 80
Change in deduction for goodwill (123) (432)
Change in deduction for identifiable intangible assets 3 (307)
Change in other adjustments 118 2,393
CET 1, Ending balance 81,641 74,850
Tier 1 Capital, Beginning balance 85,440 83,702
Change in CET1 6,791 1,734
Change in deduction for investments in covered funds 504 5
Change in other adjustments (5) (1)
Tier 1 Capital, Ending balance 92,730 85,440
Tier 2 capital, Beginning balance 13,473 13,743
Change in qualifying subordinated debt (651) (300)
Change in junior subordinated debt (96) (158)
Change in allowance for credit losses 0  
Change in other adjustments 553 188
Tier 2 Capital, Ending balance 13,279 13,473
Total capital $ 106,009 $ 98,913