Securities - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2017	Dec. 31, 2016
Securities Pledged
Amortized cost of securities	$ 83.0	$ 73.0
Fair value of pledged securities	82.6	72.6
Repurchase Agreements
Securities Pledged
Amortized cost of securities pledged	11.6	12.2
Securities pledged and available to be sold under repurchase agreements, fair value	11.6	12.2
Derivative
Securities Pledged
Amortized cost of securities pledged	4.8	5.2
Securities pledged and available to be sold under repurchase agreements, fair value	$ 4.8	$ 5.2

Amortized Cost of Securities Pledged to Various Federal Reserve Districts.

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- Definition

Fair Value of Securities Pledged to Various Federal Reserve Districts.

+ References

No definition available.

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- Definition

Amortized Cost of financial instrument held by the entity.

+ References

No definition available.

+ Details

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- Definition

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.

+ References

No definition available.

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- Definition

Fair value of financial instrument held by the entity for its own account (proprietary securities) for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

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