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, 2020		Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019		Dec. 31, 2019		Dec. 31, 2018
Assets, fair value disclosure	$ 1,176,056				$ 1,176,056				$ 1,484,478
Total Losses	452		$ 438		821		$ 512		848		$ (289)
Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	46,408				46,408				49,519
Fair Value, Inputs, Level 1 [Member]
Assets, fair value disclosure	124,497				124,497				102,941
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	1,051,546				1,051,546				1,381,498
Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	3,405				3,405				6,490
Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure	13				13				39
Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	43,003				43,003				43,029
Impaired Loans [Member]
Total Losses	0		0		0		0		0		0
Impaired Loans [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	37,381				37,381				37,082
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	37,381				37,381				37,082
Impaired Loans [Member] | Commercial Portfolio Segment [Member]
Total Losses	0		0		0		0		0		0
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	8,968				8,968				6,196
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	8,968				8,968				6,196
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	19,439				19,439				25,566
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	19,439				19,439				25,566
Impaired Loans [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member]
Total Losses	0		0		0		0		0		0
Impaired Loans [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	8,974				8,974				5,320
Impaired Loans [Member] | 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
Impaired Loans [Member] | 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
Impaired Loans [Member] | Residential Mortgage and Equity Lines Portfolio Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	8,974				8,974				5,320
Other Real Estate Owned [Member]
Total Losses	381	[1],[2]	422	[1],[2]	717	[1],[2]	494	[1],[2]	681	[3]	(619)	[3]
Other Real Estate Owned [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	7,643	[1]			7,643	[1]			10,833	[3]
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0	[1]			0	[1]			0	[3]
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	3,405	[1]			3,405	[1]			6,490	[3]
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	4,238	[1]			4,238	[1]			4,343	[3]
Investments in Venture Capital [Member]
Total Losses	71		$ 16		104		$ 18		167		$ 330
Investments in Venture Capital [Member] | Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	1,384				1,384				1,604
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	$ 1,384				$ 1,384				$ 1,604

[1] Other real estate owned balance of $7.3 million in the condensed consolidated balance sheet is net of estimated disposal costs.

[2] Other real estate owned balance of $9.0 million in the condensed consolidated balance sheet is net of estimated disposal costs.

[3] Other real estate owned balance of $10.2 million in the Consolidated Balance Sheets is net of estimated disposal costs.