Income Taxes - Reconciliation of Total Income Tax Provision, Calculated at Statutory Federal Income Tax Rates, to Income Tax Expense in Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Provision at statutory rates									$ 7,123	$ 6,528	$ 9,861
Increase/(decrease) resulting from:
State tax, net of federal tax benefit									2,188	1,717	1,277
Tax-exempt income									(599)	(580)	(1,079)
ESOP dividends									(124)	(127)	(216)
Bank owned life insurance									(129)	(140)	(205)
Benefit from stock compensation									(150)	(168)	(190)
Non-deductible Acquisition Costs									236
Impact of Tax Cuts and Jobs Act											3,870
Other									116	(23)	40
Total income tax expense	$ 2,673	$ 2,708	$ 1,540	$ 1,740	$ 1,585	$ 2,105	$ 1,901	$ 1,616	$ 8,661	$ 7,207	$ 13,358
Provision at statutory rates, Rate									21.00%	21.00%	35.00%
Increase/(decrease) resulting from: (Rate)
State tax, net of federal tax benefit, Rate									6.45%	5.52%	4.53%
Tax-exempt income, Rate									(1.77%)	(1.87%)	(3.83%)
ESOP dividends, Rate									(0.37%)	(0.41%)	(0.77%)
Bank owned life insurance, Rate									(0.38%)	(0.45%)	(0.73%)
Benefit from stock compensation, Rate									(0.44%)	(0.54%)	(0.67%)
Non-deductible Acquisition Costs, Rate									0.70%
Impact of Tax Cuts and Jobs Act, Rate											13.74%
Other, Rate									0.34%	(0.07%)	0.15%
Total income tax expense, Rate									25.53%	23.18%	47.42%