Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Note 11 - Income Taxes - Effective Income Tax Rate Reconciliation (Details)
Taxes at federal statutory rate									$ 9,489	$ 11,200	$ 13,752
Taxes at federal statutory rate, percentage									21.00%	21.00%	21.00%
State and local income tax, net of Federal income tax benefit									$ 1,043	$ 1,274	$ 1,439
State and local income tax, net of Federal income tax benefit, percentage									2.30%	2.40%	2.20%
Tax exempt									$ (875)	$ (878)	$ (1,961)
Tax exempt, percentage									(1.90%)	(1.60%)	(3.00%)
Nondeductible merger expense									$ 543	$ 328
Nondeductible merger expense, percentage									1.20%	0.60%
Other									$ 308	$ 128	$ (2,835)
Other, percentage									0.70%	0.30%	(4.30%)
Total provision for income taxes	$ 417	$ 4,489	$ 5,808	$ (206)	$ 3,957	$ 2,536	$ 3,272	$ 2,287	$ 10,508	$ 12,052	$ 10,395
Taxes at effective rate, percentage									23.30%	22.70%	15.90%