v3.21.2
Trading Cash Instruments - Fair Value, Cash Instruments, Measurement Inputs, Disclosure (Detail)
$ in Millions
Jun. 30, 2021
USD ($)
yr
Mar. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
yr
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Total financial assets at fair value | $ $ 668,710 $ 647,751 $ 627,073
Level 3 [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Total financial assets at fair value | $ 25,623 $ 26,893 26,305
Level 3 [Member] | Loans and Securities Backed by Commercial Real Estate [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Total financial assets at fair value | $ $ 96   $ 203
Level 3 [Member] | Loans and Securities Backed by Commercial Real Estate [Member] | Minimum [Member] | Fair Value Unobservable Inputs, Yield [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.067   0.017
Level 3 [Member] | Loans and Securities Backed by Commercial Real Estate [Member] | Minimum [Member] | Fair Value Unobservable Inputs, Recovery Rate [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.118   0.051
Level 3 [Member] | Loans and Securities Backed by Commercial Real Estate [Member] | Minimum [Member] | Fair Value Unobservable Inputs, Duration [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.2   1.1
Level 3 [Member] | Loans and Securities Backed by Commercial Real Estate [Member] | Maximum [Member] | Fair Value Unobservable Inputs, Yield [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.246   0.220
Level 3 [Member] | Loans and Securities Backed by Commercial Real Estate [Member] | Maximum [Member] | Fair Value Unobservable Inputs, Recovery Rate [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.923   0.949
Level 3 [Member] | Loans and Securities Backed by Commercial Real Estate [Member] | Maximum [Member] | Fair Value Unobservable Inputs, Duration [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 4.2   9.1
Level 3 [Member] | Loans and Securities Backed by Commercial Real Estate [Member] | Weighted Average [Member] | Fair Value Unobservable Inputs, Yield [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.170   0.090
Level 3 [Member] | Loans and Securities Backed by Commercial Real Estate [Member] | Weighted Average [Member] | Fair Value Unobservable Inputs, Recovery Rate [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.540   0.577
Level 3 [Member] | Loans and Securities Backed by Commercial Real Estate [Member] | Weighted Average [Member] | Fair Value Unobservable Inputs, Duration [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 2.3   5.0
Level 3 [Member] | Loans and Securities Backed by Residential Real Estate [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Total financial assets at fair value | $ $ 130   $ 131
Level 3 [Member] | Loans and Securities Backed by Residential Real Estate [Member] | Minimum [Member] | Fair Value Unobservable Inputs, Yield [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.010   0.006
Level 3 [Member] | Loans and Securities Backed by Residential Real Estate [Member] | Minimum [Member] | Fair Value Unobservable Inputs, Cumulative Loss Rate [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.012   0.034
Level 3 [Member] | Loans and Securities Backed by Residential Real Estate [Member] | Minimum [Member] | Fair Value Unobservable Inputs, Duration [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.5   0.9
Level 3 [Member] | Loans and Securities Backed by Residential Real Estate [Member] | Maximum [Member] | Fair Value Unobservable Inputs, Yield [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.365   0.157
Level 3 [Member] | Loans and Securities Backed by Residential Real Estate [Member] | Maximum [Member] | Fair Value Unobservable Inputs, Cumulative Loss Rate [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.400   0.456
Level 3 [Member] | Loans and Securities Backed by Residential Real Estate [Member] | Maximum [Member] | Fair Value Unobservable Inputs, Duration [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 11.9   16.1
Level 3 [Member] | Loans and Securities Backed by Residential Real Estate [Member] | Weighted Average [Member] | Fair Value Unobservable Inputs, Yield [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.096   0.063
Level 3 [Member] | Loans and Securities Backed by Residential Real Estate [Member] | Weighted Average [Member] | Fair Value Unobservable Inputs, Cumulative Loss Rate [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.181   0.208
Level 3 [Member] | Loans and Securities Backed by Residential Real Estate [Member] | Weighted Average [Member] | Fair Value Unobservable Inputs, Duration [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 6.0   6.5
Level 3 [Member] | Corporate debt instruments [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Total financial assets at fair value | $ $ 891   $ 797
Level 3 [Member] | Corporate debt instruments [Member] | Minimum [Member] | Fair Value Unobservable Inputs, Yield [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.019   0.006
Level 3 [Member] | Corporate debt instruments [Member] | Minimum [Member] | Fair Value Unobservable Inputs, Recovery Rate [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.000   0.000
Level 3 [Member] | Corporate debt instruments [Member] | Minimum [Member] | Fair Value Unobservable Inputs, Duration [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 1.6   0.3
Level 3 [Member] | Corporate debt instruments [Member] | Maximum [Member] | Fair Value Unobservable Inputs, Yield [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.255   0.306
Level 3 [Member] | Corporate debt instruments [Member] | Maximum [Member] | Fair Value Unobservable Inputs, Recovery Rate [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.698   0.736
Level 3 [Member] | Corporate debt instruments [Member] | Maximum [Member] | Fair Value Unobservable Inputs, Duration [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 13.8   25.5
Level 3 [Member] | Corporate debt instruments [Member] | Weighted Average [Member] | Fair Value Unobservable Inputs, Yield [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.098   0.095
Level 3 [Member] | Corporate debt instruments [Member] | Weighted Average [Member] | Fair Value Unobservable Inputs, Recovery Rate [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 0.565   0.587
Level 3 [Member] | Corporate debt instruments [Member] | Weighted Average [Member] | Fair Value Unobservable Inputs, Duration [Member]      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Fair Value Unobservable Inputs, Asset 4.3   4.0