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Fair Value of Financial Instruments - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value option elected aggregate carrying amount, asset	$ 22
Residential loans
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value option elected aggregate carrying amount, asset	3,100
Business purpose loans
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value option elected aggregate carrying amount, asset	$ 386

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- Definition

Fair Value, Option, Assets, Aggregate Carrying Amount During Period

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- Definition

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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