Investment Securities - Contractual Maturities of Investment Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Due in 1 year or less, Securities available for sale, Amortized Cost	$ 34	$ 111	$ 26
Due in 1 to 5 years, Securities available for sale, Amortized Cost	9,349	841	1,722
Due in 5 to 10 years, Securities available for sale, Amortized Cost	71,309	29,003	34,382
Due after 10 years, Securities available for sale, Amortized Cost	230,549	270,594	269,650
Equity securities, Amortized Cost	2,978	3,296	3,266
Amortized Cost	314,219
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Due in 1 year or less, Securities available for sale, Fair Value (Estimated)	34	112	26
Due in 1 to 5 years, Securities available for sale, Fair Value (Estimated)	9,341	842	1,758
Due in 5 to 10 years, Securities available for sale, Fair Value (Estimated)	69,745	29,177	35,099
Due after 10 years, Securities available for sale, Fair Value (Estimated)	222,950	266,627	267,936
Other equity securities	2,978	3,414	3,327
Securities available for sale, Fair Value (Estimated)	305,048
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Due in 1 year or less, Securities to be held to maturity, Amortized Cost	1,327	635	707
Due in 1 to 5 years, Securities to be held to maturity, Amortized Cost	23,621	18,059	14,536
Due in 5 to 10 years, Securities to be held to maturity, Amortized Cost	155,096	37,182	41,373
Due after 10 years, Securities to be held to maturity, Amortized Cost	80,033	200,691	187,507
Securities to be held to maturity, Amortized Cost	260,077	256,567	244,123
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Due in 1 year or less, Securities to be held to maturity, Fair Value (Estimated)	1,329	637	710
Due in 1 to 5 years, Securities to be held to maturity, Fair Value (Estimated)	23,698	18,164	14,813
Due in 5 to 10 years, Securities to be held to maturity, Fair Value (Estimated)	153,240	37,719	42,251
Due after 10 years, Securities to be held to maturity, Fair Value (Estimated)	78,049	203,135	188,464
Securities to be held to maturity, Fair Value (Estimated)	$ 256,316	$ 259,655	$ 246,238

Debt Securities, Available-for-sale, Amortized Cost and Equity Securities

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