Investment Securities Available for Sale (Narrative) (Details)	Jun. 30, 2021 USD ($) security	Dec. 31, 2020 USD ($)
Financing Receivable, Impaired [Line Items]
Investment securities in a loss position for less than twelve months \| security	91
Investment securities in a loss position for twelve months or longer \| security	8
Allowance for credit loss \| $	$ 0
Collateral Pledged
Financing Receivable, Impaired [Line Items]
Pledged to secure deposits \| $	$ 3,730,000,000	$ 3,840,000,000

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without an allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

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-Publisher FASB
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Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without an allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

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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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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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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No definition available.

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