Note 7 - Loans - Non-accrual Troubled Debt Restructurings (Details) - Non-accruing Troubled Debt Restructuring [Member] - USD ($) $ in Thousands	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Accruing TDRs	$ 30,045	$ 32,779	$ 29,722	$ 25,442	$ 23,209	$ 39,923
Payment Deferral [Member]
Accruing TDRs	13,634		17,431
Contractual Interest Rate Reduction [Member]
Accruing TDRs	1,736		1,795
Rate Reduction and Payment Deferral [Member]
Accruing TDRs	14,675		10,496
Commercial Portfolio Segment [Member]
Accruing TDRs	12,804		14,565
Commercial Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	12,804		14,565
Commercial Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs
Commercial Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs
Commercial Real Estate Portfolio Segment [Member]
Accruing TDRs	16,957		14,633
Commercial Real Estate Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	707		2,510
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	1,736		1,795
Commercial Real Estate Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	14,514		10,328
Residential Portfolio Segment [Member]
Accruing TDRs	284		524
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	123		356
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs
Residential Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	$ 161		$ 168