Investment Securities, Securities in Continuous Unrealized Loss Position (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($) Security	Dec. 31, 2017 USD ($) Security	Sep. 30, 2017 USD ($) Security
Investment Securities [Abstract]
Number of investment securities held | Security	431
Less than 12 months, number of positions | Security	132
12 months or more, number of positions | Security	88
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value	$ 271,523	$ 229,523	$ 215,970
Less than 12 months, unrealized loss	6,124	1,127	1,154
12 months or more, fair value	111,641	105,991	0
12 months or more, unrealized loss	3,471	1,050	0
Total, fair value	383,164	335,514	215,970
Total, unrealized loss	9,595	2,177	1,154
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value	15,309
Less than 12 months, unrealized loss	174
12 months or more, fair value	0
12 months or more, unrealized loss	0
Total, fair value	15,309
Total, unrealized loss	174	0	0
Obligations of States and Political Subdivisions [Member]
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value	15,309
Less than 12 months, unrealized loss	174
12 months or more, fair value	0
12 months or more, unrealized loss	0
Total, fair value	15,309
Total, unrealized loss	$ 174	$ 0	$ 0
Less than 12 months, number of positions | Security	39
12 months or more, number of positions | Security	0
Municipal Bonds [Member]
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Percentage of bank qualified municipal bond portfolio rated	99.00%
Percentage of portfolio not rated	1.00%
Government Agency & Government-Sponsored Entities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, number of positions | Security	0	0	0
12 months or more, number of positions | Security	0	0	0
US Treasury Notes [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value	$ 84,315	$ 94,281	$ 74,414
Less than 12 months, unrealized loss	290	144	249
12 months or more, fair value	24,902	49,883	0
12 months or more, unrealized loss	173	298	0
Total, fair value	109,217	144,164	74,414
Total, unrealized loss	$ 463	442	249
Less than 12 months, number of positions | Security	10
12 months or more, number of positions | Security	1
US Govt SBA [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value	$ 4,965	8,379	18,669
Less than 12 months, unrealized loss	62	51	86
12 months or more, fair value	8,467	12,900	0
12 months or more, unrealized loss	115	157	0
Total, fair value	13,432	21,279	18,669
Total, unrealized loss	$ 177	208	86
Less than 12 months, number of positions | Security	27
12 months or more, number of positions | Security	45
Mortgage Backed Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value	$ 182,243	126,863	122,887
Less than 12 months, unrealized loss	5,772	932	819
12 months or more, fair value	78,272	43,208	0
12 months or more, unrealized loss	3,183	595	0
Total, fair value	260,515	170,071	122,887
Total, unrealized loss	$ 8,955	$ 1,527	$ 819
Less than 12 months, number of positions | Security	56
12 months or more, number of positions | Security	42