Shareholders' Equity - Components of Company's Regulatory Capital Requirements Under Banking Regulations (Detail) (Parenthetical)	Dec. 31, 2019	Dec. 31, 2018
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital conservation buffer ratio	2.50%	1.875%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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