Securities - Investments in continuous unrealized loss position (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Held to Maturity, Fair Value, Less than Twelve Months	$ 7,324	$ 3,389
Held to Maturity, Gross Unrealized Losses, Less than Twelve Months	(609)	(68)
Held to Maturity, Fair Value, Twelve Months or Greater	0	0
Held to Maturity, Gross Unrealized Losses, Twelve Months or Greater	0	0
Held to Maturity, Fair Value	7,324	3,389
Held to Maturity, Gross Unrealized Losses, Total	(609)	(68)
Available for Sale, Fair Value, Less than Twelve Months	128,686	134,167
Available for Sale, Gross Unrealized Losses, Less than Twelve Months	(1,979)	(1,721)
Available for Sale, Fair Value, Twelve Months or Greater	54,756	32,790
Available for Sale, Gross Unrealized Losses, Twelve Months or Greater	(2,195)	(1,239)
Available for Sale, Fair Value, Total	183,442	166,957
Available for Sale, Gross Unrealized Losses, Total	(4,174)	(2,960)
U.S. government agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Fair Value, Less than Twelve Months	46,700	46,000
Available for Sale, Gross Unrealized Losses, Less than Twelve Months	(495)	(304)
Available for Sale, Fair Value, Twelve Months or Greater	7,174	4,223
Available for Sale, Gross Unrealized Losses, Twelve Months or Greater	(76)	(76)
Available for Sale, Fair Value, Total	53,874	50,223
Available for Sale, Gross Unrealized Losses, Total	(571)	(380)
Obligations of states and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Held to Maturity, Fair Value, Less than Twelve Months	5,839	1,419
Held to Maturity, Gross Unrealized Losses, Less than Twelve Months	(594)	(38)
Held to Maturity, Fair Value, Twelve Months or Greater	0	0
Held to Maturity, Gross Unrealized Losses, Twelve Months or Greater	0	0
Held to Maturity, Fair Value	5,839	1,419
Held to Maturity, Gross Unrealized Losses, Total	(594)	(38)
Available for Sale, Fair Value, Less than Twelve Months	12,670	16,559
Available for Sale, Gross Unrealized Losses, Less than Twelve Months	(257)	(324)
Available for Sale, Fair Value, Twelve Months or Greater	6,968	1,082
Available for Sale, Gross Unrealized Losses, Twelve Months or Greater	(285)	(110)
Available for Sale, Fair Value, Total	19,638	17,641
Available for Sale, Gross Unrealized Losses, Total	(542)	(434)
Mortgage-backed securities, Agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Fair Value, Less than Twelve Months	51,018	27,627
Available for Sale, Gross Unrealized Losses, Less than Twelve Months	(634)	(402)
Available for Sale, Fair Value, Twelve Months or Greater	13,020	9,911
Available for Sale, Gross Unrealized Losses, Twelve Months or Greater	(510)	(343)
Available for Sale, Fair Value, Total	64,038	37,538
Available for Sale, Gross Unrealized Losses, Total	(1,144)	(745)
Mortgage-backed securities, Non-agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Fair Value, Less than Twelve Months	5,379	7,842
Available for Sale, Gross Unrealized Losses, Less than Twelve Months	(68)	(37)
Available for Sale, Fair Value, Twelve Months or Greater	1,944	671
Available for Sale, Gross Unrealized Losses, Twelve Months or Greater	(6)	(1)
Available for Sale, Fair Value, Total	7,323	8,513
Available for Sale, Gross Unrealized Losses, Total	(74)	(38)
Other Asset Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale, Fair Value, Less than Twelve Months	7,007	25,399
Available for Sale, Gross Unrealized Losses, Less than Twelve Months	(284)	(276)
Available for Sale, Fair Value, Twelve Months or Greater	16,388	12,037
Available for Sale, Gross Unrealized Losses, Twelve Months or Greater	(332)	(327)
Available for Sale, Fair Value, Total	23,395	37,436
Available for Sale, Gross Unrealized Losses, Total	(616)	(603)
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Held to Maturity, Fair Value, Less than Twelve Months	1,485	1,970
Held to Maturity, Gross Unrealized Losses, Less than Twelve Months	(15)	(30)
Held to Maturity, Fair Value, Twelve Months or Greater	0	0
Held to Maturity, Gross Unrealized Losses, Twelve Months or Greater	0	0
Held to Maturity, Fair Value	1,485	1,970
Held to Maturity, Gross Unrealized Losses, Total	(15)	(30)
Available for Sale, Fair Value, Less than Twelve Months	5,912	10,740
Available for Sale, Gross Unrealized Losses, Less than Twelve Months	(241)	(378)
Available for Sale, Fair Value, Twelve Months or Greater	9,262	4,866
Available for Sale, Gross Unrealized Losses, Twelve Months or Greater	(986)	(382)
Available for Sale, Fair Value, Total	15,174	15,606
Available for Sale, Gross Unrealized Losses, Total	$ (1,227)	$ (760)

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss1

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This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

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Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity that have been in a continuous loss position for twelve months or longer.

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Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity in a continuous loss position.

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