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Regulatory Capital - Additional Information (Detail)
Dec. 31, 2019
Dec. 31, 2017
Dec. 31, 2015
Schedule Of Regulatory Assets And Liabilities [Line Items]      
Capital conservation buffer   1.25% 0.00%
Scenario, Forecast [Member]      
Schedule Of Regulatory Assets And Liabilities [Line Items]      
Capital conservation buffer 2.50%