Investments (Gross Unrealized Losses and Fair Values of Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Investments [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than twelve months, fair value	$ 44,634	$ 47,594
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	1,215	754
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value	91,636	82,737
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	6,644	6,695
Held-to-maturity securities, continuous unrealized loss position, less than twelve months, fair value	45,252	27,302
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, unrealized loss	880	149
Held-to-maturity securities, continuous unrealized loss position, twelve months or longer, fair value	16,378	14,540
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, unrealized loss	780	357
US government agencies [Member]
Schedule of Investments [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than twelve months, fair value	4,865	4,931
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	136	69
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value	23,996	24,325
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	1,003	675
Residential mortgage-backed agencies [Member]
Schedule of Investments [Line Items]
Held-to-maturity securities, continuous unrealized loss position, less than twelve months, fair value	34,240	15,897
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, unrealized loss	632	135
Held-to-maturity securities, continuous unrealized loss position, twelve months or longer, fair value	12,510	10,422
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, unrealized loss	593	288
Commercial mortgage-backed agencies [Member]
Schedule of Investments [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than twelve months, fair value	12,384	12,593
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	390	169
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value	27,644	28,298
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	1,013	711
Held-to-maturity securities, continuous unrealized loss position, less than twelve months, fair value	8,717	9,028
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, unrealized loss	158	6
Held-to-maturity securities, continuous unrealized loss position, twelve months or longer, fair value	0	0
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, unrealized loss	0	0
Collateralized mortgage obligations [Member]
Schedule of Investments [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than twelve months, fair value	16,982	27,387
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	538	472
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value	21,438	12,447
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	803	443
Held-to-maturity securities, continuous unrealized loss position, less than twelve months, fair value	0	0
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, unrealized loss	0	0
Held-to-maturity securities, continuous unrealized loss position, twelve months or longer, fair value	3,868	4,118
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, unrealized loss	187	69
Obligations of states and political subdivisions [Member]
Schedule of Investments [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than twelve months, fair value	10,403	2,683
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	151	44
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value	2,581	2,747
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	96	75
Held-to-maturity securities, continuous unrealized loss position, less than twelve months, fair value	2,295	2,377
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, unrealized loss	90	8
Held-to-maturity securities, continuous unrealized loss position, twelve months or longer, fair value	0	0
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, unrealized loss	0	0
Collateralized debt obligations [Member]
Schedule of Investments [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than twelve months, fair value	0	0
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	0	0
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value	15,977	14,920
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	$ 3,729	$ 4,791

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

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