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Short-term Borrowings (Narrative) (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2017 USD ($)
Fixed Income |
Short-term Debt [Line Items] |
Trading Securities Pledged as Collateral | $ 68.9
Federal Funds Purchased |
Short-term Debt [Line Items] |
Maximum maturity days | 90 days
Trading Liabilities |
Short-term Debt [Line Items] |
Maximum holding days | 90 days
Other Short-term Borrowings |
Short-term Debt [Line Items] |
Maximum original maturity period | 1 year

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- Definition The fair value of trading securities that serve as collateral for borrowings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5086-111524 + Details
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