Investment Securities, Securities in Continuous Unrealized Loss Position (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) Security	Dec. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)
Investment Securities, Qualitative Disclosure [Abstract]
Number of investment securities held | Security	551
Less than 12 months, number of positions | Security	25
12 months or more, number of positions | Security	72
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value	$ 3,961	$ 133,698	$ 156,706
12 months or more, fair value	4,929	5,911	206,184
Total, fair value	8,890	139,609	362,890
Less than 12 months, unrealized loss	7	94	53
12 months or more, unrealized loss	99	118	1,767
Total, unrealized loss	106	212	1,820
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value	728	355	229
Less than 12 months, unrealized loss	10	12	1
12 months or more, fair value	0	0	360
12 months or more, unrealized loss	0	0	0
Total, fair value	728	355	589
Total, unrealized loss	10	12	1
Obligations of States and Political Subdivisions [Member]
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value	728	355	229
Less than 12 months, unrealized loss	10	12	1
12 months or more, fair value	0	0	360
12 months or more, unrealized loss	0	0	0
Total, fair value	728	355	589
Total, unrealized loss	$ 10	12	1
Less than 12 months, number of positions | Security	4
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	100.00%
US Treasury Notes [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value			149,962
12 months or more, fair value			4,909
Total, fair value			154,871
Less than 12 months, unrealized loss			28
12 months or more, unrealized loss			6
Total, unrealized loss	$ 0	0	34
Less than 12 months, number of positions | Security	0
12 months or more, number of positions | Security	0
US Govt SBA [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value	$ 2,458	2,693	1,310
12 months or more, fair value	4,674	5,198	10,823
Total, fair value	7,132	7,891	12,133
Less than 12 months, unrealized loss	5	6	0
12 months or more, unrealized loss	93	107	147
Total, unrealized loss	$ 98	113	147
Less than 12 months, number of positions | Security	16
12 months or more, number of positions | Security	53
Mortgage Backed Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value	$ 1,503	131,005	5,434
12 months or more, fair value	255	713	190,452
Total, fair value	1,758	131,718	195,886
Less than 12 months, unrealized loss	2	88	25
12 months or more, unrealized loss	6	11	1,614
Total, unrealized loss	$ 8	$ 99	$ 1,639
Less than 12 months, number of positions | Security	5
12 months or more, number of positions | Security	19