Note 12 - Assets and Liabilities Measured and Reported at Fair Value - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Securities available-for-sale	$ 1,070,148	$ 586,978
US Treasury Securities and US Government Agencies Debt Securities [Member]
Securities available-for-sale	83,712
US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	146,287	138,078
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available-for-sale	771,722	437,585
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale	67,424	11,315
Other Debt Obligations [Member]
Securities available-for-sale	1,003
Fair Value, Recurring [Member]
Securities available-for-sale	1,070,148	586,978
Interest rate swaps	4,180	8,374
Total assets	1,074,328	595,352
Interest rate swaps	4,226	8,391
Fair Value, Recurring [Member] | US Treasury Securities and US Government Agencies Debt Securities [Member]
Securities available-for-sale	83,712
Fair Value, Recurring [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	146,287	138,078
Fair Value, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available-for-sale	771,722	437,585
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale	67,424	11,315
Fair Value, Recurring [Member] | Other Debt Obligations [Member]
Securities available-for-sale	1,003
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	83,712	0
Interest rate swaps	0	0
Total assets	83,712	0
Interest rate swaps	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US Treasury Securities and US Government Agencies Debt Securities [Member]
Securities available-for-sale	83,712
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available-for-sale	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other Debt Obligations [Member]
Securities available-for-sale	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	986,436	586,978
Interest rate swaps	4,180	8,374
Total assets	990,616	595,352
Interest rate swaps	4,226	8,391
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US Treasury Securities and US Government Agencies Debt Securities [Member]
Securities available-for-sale	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	146,287	138,078
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available-for-sale	771,722	437,585
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale	67,424	11,315
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other Debt Obligations [Member]
Securities available-for-sale	1,003
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Interest rate swaps	0	0
Total assets	0	0
Interest rate swaps	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US Treasury Securities and US Government Agencies Debt Securities [Member]
Securities available-for-sale	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available-for-sale	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale	0	$ 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other Debt Obligations [Member]
Securities available-for-sale	$ 0