Securities - Amortized Cost to Approximate Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Available-for-sale securities:
Amortized Cost	$ 431,373	$ 326,931
Gross Unrealized Gains	1
Gross Unrealized Losses	793	1,057
Available for sale securities	430,581	325,874
Treasury notes
Available-for-sale securities:
Amortized Cost	1,000	999
Gross Unrealized Losses	3
Available for sale securities	997	999
Federal agencies
Available-for-sale securities:
Amortized Cost	404,306	290,050
Gross Unrealized Gains	1
Gross Unrealized Losses	790	1,057
Available for sale securities	403,517	288,993
Municipals
Available-for-sale securities:
Amortized Cost		9,500
Available for sale securities		9,500
Mortgage-backed - Government-sponsored entity (GSE) - residential
Available-for-sale securities:
Amortized Cost	26,067	26,382
Available for sale securities	$ 26,067	$ 26,382

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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-Publisher FASB
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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Topic 320
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-Section 50
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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