Other Assets - Intangible Assets Disclosure - Additional Information (Detail) - Other [Member] - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Identifiable intangible assets	$ 155	$ 515
Identifiable intangible assets approximate weighted average remaining life in years	10 years	10 years

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.

No definition available.

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