Short-Term Debt (Narrative) (Details) - USD ($) $ in Billions	Dec. 31, 2020	Dec. 31, 2019
Investment Securities And One To Four Family Residential Property Loans
Short-term Debt [Line Items]
Collateral pledged to the FHLB	$ 2.2	$ 2.3
City National
Short-term Debt [Line Items]
FHLB stock purchased during year	37,000
Unused and available FHLB funds	$ 2.0	$ 1.9

Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22 (b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13(3)(a))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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