Investments (Narrative) (Details) $ in Millions	Jun. 30, 2020 USD ($) hTMNumber numberOfBranches	Dec. 31, 2019 USD ($) hTMNumber numberOfBranches
Debt and Equity Securities, FV-NI [Line Items]
Accrued interest receivable	$ 183	$ 164
Held-to-maturity, Amortized cost	$ 688
Number of HTM investment securities in an unrealized loss position \| hTMNumber	103	146
Number of AFS investment securities in an unrealized loss position \| numberOfBranches	520	849
Allowance for credit loss on HTM securities	$ 1
Carrying value of pledged securities	2,000	$ 2,000
Securities Investment [Member]
Debt and Equity Securities, FV-NI [Line Items]
Accrued interest receivable	$ 54	$ 58

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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