Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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This item represents the estimated amount of gains or losses included in earnings during the period attributable to changes in instrument-specific credit risk arising from loans and other receivables held as assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14172-108612

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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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Fair Value of Assets & Liabilities (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Gain/(loss) on instrument specific credit risk				$ 0.5	$ 1.5	$ 0.4
Corporate
Segment Reporting Information [Line Items]
Long-lived asset impairment	$ 3.0	$ 2.0
Regional Banking
Segment Reporting Information [Line Items]
Long-lived asset impairment	$ 0.8		$ 3.7