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Securities - Unrealized Loss Positions (Details)	Dec. 31, 2018 USD ($) security	Dec. 31, 2017 USD ($) security
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position	16	26
Greater than 12 months in an unrealized loss position	61	22
Total | security	77	48
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position	$ 1,256,000	$ 1,457,000
Greater than 12 months in an unrealized loss position	7,592,000	3,216,000
Total	8,848,000	4,673,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position	86,856,000	102,830,000
Greater than 12 months in an unrealized loss position	197,238,000	108,651,000
Total	$ 284,094,000	$ 211,481,000
U.S. Treasury
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position		1
Greater than 12 months in an unrealized loss position | security	1
Total | security	1	1
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position		$ 55,000
Greater than 12 months in an unrealized loss position	$ 83,000
Total	83,000	55,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position		3,947,000
Greater than 12 months in an unrealized loss position	3,923,000
Total	$ 3,923,000	$ 3,947,000
U.S. government agencies
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position	3	2
Greater than 12 months in an unrealized loss position | security	1
Total | security	4	2
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position	$ 100,000	$ 9,000
Greater than 12 months in an unrealized loss position	61,000
Total	161,000	9,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position	7,385,000	6,550,000
Greater than 12 months in an unrealized loss position	3,566,000
Total	$ 10,951,000	$ 6,550,000
U.S. government agency mortgage-backed
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position		4
Greater than 12 months in an unrealized loss position	11	5
Total | security	11	9
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position		$ 24,000
Greater than 12 months in an unrealized loss position	$ 377,000	141,000
Total	377,000	165,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position		5,501,000
Greater than 12 months in an unrealized loss position	11,439,000	4,843,000
Total	$ 11,439,000	$ 10,344,000
States and political subdivisions
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position	4	13
Greater than 12 months in an unrealized loss position	33	1
Total | security	37	14
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position	$ 126,000	$ 1,237,000
Greater than 12 months in an unrealized loss position	4,835,000	27,000
Total	4,961,000	1,264,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position	17,713,000	45,985,000
Greater than 12 months in an unrealized loss position	110,326,000	1,512,000
Total	$ 128,039,000	$ 47,497,000
Corporate bonds
Securities Available-for-Sale, Number of Securities
Greater than 12 months in an unrealized loss position		1
Total | security		1
Securities Available-for-Sale, Unrealized Losses
Greater than 12 months in an unrealized loss position		$ 11,000
Total		11,000
Securities Available-for-Sale, Fair Value
Greater than 12 months in an unrealized loss position		332,000
Total		$ 332,000
Collateralized mortgage obligations
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position	2	3
Greater than 12 months in an unrealized loss position	10	8
Total | security	12	11
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position	$ 309,000	$ 31,000
Greater than 12 months in an unrealized loss position	1,835,000	1,124,000
Total	2,144,000	1,155,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position	15,211,000	11,534,000
Greater than 12 months in an unrealized loss position	43,687,000	40,219,000
Total	$ 58,898,000	$ 51,753,000
Asset-backed securities
Securities Available-for-Sale, Number of Securities
Greater than 12 months in an unrealized loss position	4	7
Total | security	4	7
Securities Available-for-Sale, Unrealized Losses
Greater than 12 months in an unrealized loss position	$ 225,000	$ 1,913,000
Total	225,000	1,913,000
Securities Available-for-Sale, Fair Value
Greater than 12 months in an unrealized loss position	16,473,000	61,745,000
Total	$ 16,473,000	$ 61,745,000
Collateralized loan obligations
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position	7	3
Greater than 12 months in an unrealized loss position | security	1
Total | security	8	3
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position	$ 721,000	$ 101,000
Greater than 12 months in an unrealized loss position	176,000
Total	897,000	101,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position	46,547,000	29,313,000
Greater than 12 months in an unrealized loss position	7,824,000
Total	$ 54,371,000	$ 29,313,000

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