Investment Securities, Securities in Continuous Unrealized Loss Position (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Security	Dec. 31, 2017 USD ($)
Available-for-sale Securities in Continuous Unrealized Loss Position [Abstract]
Less than 12 months fair value	$ 180,524	$ 229,523
Less than 12 months unrealized loss	563	1,127
12 months or more fair value	255,418	105,991
12 months or more unrealized loss	4,888	1,050
Total fair value	435,942	335,514
Total unrealized loss	$ 5,451	2,177
Number of investment securities held | Security	636
Less than 12 months, number of positions | Security	83
12 months or more, number of positions | Security	120
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months fair value	$ 6,052
Less than 12 months unrealized loss	23
12 months or more fair value	849
12 months or more unrealized loss	16
Total fair value	6,901
Total unrealized loss	39	0
Obligations of States and Political Subdivisions [Member]
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months fair value	6,052
Less than 12 months unrealized loss	23
12 months or more fair value	849
12 months or more unrealized loss	16
Total fair value	6,901
Total unrealized loss	$ 39
Less than 12 months, number of positions | Security	16
12 months or more, number of positions | Security	2
Municipal Bonds [Member]
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Percentage of portfolio rated at either issue or issuer level	99.00%
Percentage of portfolio not rated	1.00%
Government Agency & Government-Sponsored Entities [Member]
Available-for-sale Securities in Continuous Unrealized Loss Position [Abstract]
Less than 12 months, number of positions | Security	0
12 months or more, number of positions | Security	0
US Treasury Notes [Member]
Available-for-sale Securities in Continuous Unrealized Loss Position [Abstract]
Less than 12 months fair value	$ 124,985	94,281
Less than 12 months unrealized loss	7	144
12 months or more fair value	39,529	49,883
12 months or more unrealized loss	151	298
Total fair value	164,514	144,164
Total unrealized loss	$ 158	442
Less than 12 months, number of positions | Security	13
12 months or more, number of positions | Security	4
US Govt SBA [Member]
Available-for-sale Securities in Continuous Unrealized Loss Position [Abstract]
Less than 12 months fair value	$ 3,250	8,379
Less than 12 months unrealized loss	28	51
12 months or more fair value	8,618	12,900
12 months or more unrealized loss	132	157
Total fair value	11,868	21,279
Total unrealized loss	$ 160	208
Less than 12 months, number of positions | Security	17
12 months or more, number of positions | Security	53
Mortgage Backed Securities [Member]
Available-for-sale Securities in Continuous Unrealized Loss Position [Abstract]
Less than 12 months fair value	$ 52,289	126,863
Less than 12 months unrealized loss	528	932
12 months or more fair value	207,271	43,208
12 months or more unrealized loss	4,605	595
Total fair value	259,560	170,071
Total unrealized loss	$ 5,133	$ 1,527
Less than 12 months, number of positions | Security	37
12 months or more, number of positions | Security	61