Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income, before tax amount	$ 7,260	$ 6,464
Income tax expense	1,520	1,235
Net income	5,740	5,229
Debt securities available for sale:
Unrealized holding gains on securities arising during the period, before tax	313	(807)
Unrealized holding gains on securities arising during the period, tax	73	(226)
Unrealized holding gains on securities arising during the period, net	240	(581)
Less: reclassification adjustment for gains on securities included in net income, before tax	100	0
Less: reclassification adjustment for gains on securities included in net income, tax	21	0
Total reclassification adjustment for gains on securities included in net income	79	0
Total unrealized gains on securities available for sale, before tax	213	(807)
Total unrealized gains on securities available for sale, tax	52	(226)
Total unrealized gains on securities available for sale, net of tax	161	(581)
Adjustments related to defined benefit plan:
Amortization of prior service cost, before tax	21	21
Amortization of prior service cost, tax	(70)	155
Amortization of prior service cost, net of tax	91	(134)
Total adjustments related to defined benefit plan, before tax	21	21
Total adjustments related to defined benefit plan, tax	(70)	155
Total adjustments related to defined benefit plan	91	(134)
Net unrealized (losses) gains from cash flow hedges:
Unrealized holding loss on cash flow hedges arising during the period, before tax	(408)	583
Unrealized holding loss on cash flow hedges arising during the period, tax	(106)	34
Unrealized holding loss on cash flow hedges arising during the period, net of tax	(302)	549
Total unrealized loss on cash flow hedges, before tax	(408)	583
Total unrealized loss on cash flow hedges, tax	(106)	34
Total unrealized loss on cash flow hedges, net of tax	(302)	549
Total other comprehensive income, before tax	(174)	(203)
Total other comprehensive income, tax	(124)	(37)
Total other comprehensive income, net	(50)	(166)
Total comprehensive income, before tax	7,086	6,261
Total comprehensive income, tax	1,396	1,198
Total comprehensive income	$ 5,690	$ 5,063