For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount of interest income on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), from change in present value of expected cash flows, attributable to passage of time.

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Amount of restricted investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of obligation to return securities collateral under master netting arrangements that have not been offset against derivative assets.

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The cumulative amount of the reporting entity's undistributed earnings or deficit.

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Investment Securities - Additional Information (Details) - USD ($) $ in Millions			12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Jan. 01, 2020
Debt Securities, Available-for-sale [Line Items]
Increase in retained earnings	$ 40,088	$ 40,340	$ 40,088
Accrued interest receivable			230
Derivative, collateral, obligation to return securities	$ 1	$ 1	1
Investment securities portfolio \| US Treasury and Agency securities
Debt Securities, Available-for-sale [Line Items]
Percentage of portfolio	96.00%	96.00%
Collateral pledged
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, restricted	$ 16,500	$ 14,000	$ 16,500
Cumulative effects from adoption of new accounting standards
Debt Securities, Available-for-sale [Line Items]
Increase in retained earnings				$ 11