Securities Sold Under Agreements to Repurchase - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2017	Sep. 30, 2017
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Abstract]
Securities sold under agreements to repurchase	$ 152.8	$ 139.3
Securities sold under agreements to repurchase, fair value of collateral	$ 149.8	$ 137.4
Securities sold under agreements to repurchase, collateral, percentage of borrowed funds (as a percent)	102.00%

Securities Sold under Agreements to Repurchase, Collateral, Percentage of Total Borrowed Funds

No definition available.

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- References

No definition available.

+ Details

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- Definition

Fair value of securities pledged as collateral against securities sold under agreement to repurchase.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226013-175313

+ Details

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- Definition

Amount, before effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226000-175313

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

+ Details

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