Note 13 - Fair Value Measurements - Financial Assets and Liabilities Measured on a Non-recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended				12 Months Ended
	Jun. 30, 2019		Jun. 30, 2018		Jun. 30, 2019		Jun. 30, 2018		Dec. 31, 2018		Dec. 31, 2017
Assets, fair value disclosure	$ 1,506,204				$ 1,506,204				$ 1,275,998
Total Losses	438		$ 58		512		$ 264		(289)		$ 874
Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	56,280				56,280				53,297
Fair Value, Inputs, Level 1 [Member]
Assets, fair value disclosure	82,289				82,289				149,849
Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0				0				0
Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure	1,423,871				1,423,871				1,125,965
Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	7,625				7,625				9,023
Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure	44				44				184
Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	48,655				48,655				44,274
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Total Losses	0		0		0		0		0		0
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	5,750				5,750				6,850
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0				0				0
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0				0				0
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	5,750				5,750				6,850
Impaired Loans [Member]
Total Losses	0		0		0		0		0		25
Impaired Loans [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	42,566				42,566				37,769
Impaired Loans [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0				0				0
Impaired Loans [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0				0				0
Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	42,566				42,566				37,769
Impaired Loans [Member] | Commercial Portfolio Segment [Member]
Total Losses	0		0		0		0		0		25
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	11,731				11,731				4,733
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0				0				0
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0				0				0
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	11,731				11,731				4,733
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member]
Total Losses	0		0		0		0		0		0
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	25,085				25,085				26,186
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0				0				0
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0				0				0
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	25,085				25,085				26,186
Other Real Estate Owned [Member]
Total Losses	422	[1]	(33)	[1]	494	[1]	0	[1]	(619)	[2]	457	[2]
Other Real Estate Owned [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	11,968	[1]			11,968	[1]			13,366	[2]
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0	[1]			0	[1]			0	[2]
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	7,625	[1]			7,625	[1]			9,023	[2]
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	4,343	[1]			4,343	[1]			4,343	[2]
Investments in Venture Capital [Member]
Total Losses	16		$ 91		18		$ 264		330		$ 392
Investments in Venture Capital [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	1,746				1,746				2,162
Investments in Venture Capital [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0				0				0
Investments in Venture Capital [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0				0				0
Investments in Venture Capital [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	$ 1,746				$ 1,746				$ 2,162

[1] Other real estate owned balance of $11.3 million in the condensed consolidated balance sheet is net of estimated disposal costs.

[2] Other real estate owned balance of $12.7 million in the Consolidated Balance Sheets is net of estimated disposal costs.