Note 20 - Segments - Financial Information by Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Net interest income	$ 32,070			$ 28,521			$ 92,501	$ 84,504
Provision	400			735			1,000	2,705
Non-interest income	5,738			5,380			16,839	16,224
All other non-interest income	7,566			6,046			19,790	17,546
Non-interest expenses	23,957			21,781			72,060	64,944
Income before income tax expense	21,017			17,431			56,070	50,625
Income tax expense	3,783			3,555			6,652	9,766
Net income	17,234	$ 16,543	$ 15,641	13,876	$ 13,579	$ 13,404	49,418	40,859
Segment assets	3,533,926			3,324,797			3,533,926	3,324,797	$ 3,302,924
Commercial Banking [Member]
Net interest income	31,995			28,462			92,266	84,312
Provision	400			735			1,000	2,705
Non-interest income	0			0			0	0
All other non-interest income	7,566			6,046			19,790	17,546
Non-interest expenses	20,822			18,774			62,725	55,572
Income before income tax expense	18,339			14,999			48,331	43,581
Income tax expense	3,202			3,027			4,973	8,237
Net income	15,137			11,972			43,358	35,344
Segment assets	3,530,198			3,320,838			3,530,198	3,320,838
Investment Management and Trust [Member]
Net interest income	75			59			235	192
Provision	0			0			0	0
Non-interest income	5,738			5,380			16,839	16,224
All other non-interest income	0			0			0	0
Non-interest expenses	3,135			3,007			9,335	9,372
Income before income tax expense	2,678			2,432			7,739	7,044
Income tax expense	581			528			1,679	1,529
Net income	2,097			1,904			6,060	5,515
Segment assets	$ 3,728			$ 3,959			$ 3,728	$ 3,959