AFS Securities (Amortized cost and fair value of AFS securities, with gross unrealized gains and losses) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 555,001	$ 547,912
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2,416	5,036
Gross Unrealized Gains	9,655	4,218
AFS securities	547,762	548,730
Government sponsored enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	205	217
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0	0
Gross Unrealized Gains	3	1
AFS securities	202	216
States and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	209,788	204,131
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2,240	4,486
Gross Unrealized Gains	395	143
AFS securities	211,633	208,474
Auction rate money market preferred [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,200	3,200
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0	0
Gross Unrealized Gains	188	151
AFS securities	3,012	3,049
Mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	212,713	210,757
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	103	390
Gross Unrealized Gains	5,955	2,350
AFS securities	206,861	208,797
Collateralized mortgage obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	129,095	129,607
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	73	160
Gross Unrealized Gains	3,114	1,573
AFS securities	$ 126,054	$ 128,194

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

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- Definition

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

+ References

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- Definition

This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Amount of debt securities categorized neither as held-to-maturity nor trading.

+ References

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=65884222&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 2
-Subparagraph (b)-(g)
-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803

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