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Regulatory Capital - Additional Information (Detail) - USD ($)
Jan. 01, 2019
Mar. 31, 2020
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Capital conservation buffer risk-weighted assets 2.50%  
Maximum asset value required to be maintained leverage ratio   $ 10,000,000,000
Minimum [Member]    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Leverage ratio   8.00%
Maximum [Member]    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Leverage ratio   9.00%