Investment Securities - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investment Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sale of available-for-sale investment securities	$ 10,218	$ 186,769	$ 83,735
Available-for-sale Securities, Gross Realized Gains	100	100	100
Available-for-sale Securities, Gross Realized Losses	$ 0	$ 100	$ 0
Fixed Interest Rate [Member] \| Government/GSE Guaranteed Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-Maturity Securities, Debt Maturities, Weighted-Average Yield	2.50%

Held-to-Maturity Securities, Debt Maturities, Weighted-Average Yield

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- Definition

This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563

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This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

+ References

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- Definition

The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26853-111562

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (a),(b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

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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.

+ References

No definition available.

+ Details

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