Note 8 - Loans - Allowance for Loan Losses by Portfolio Segment and Based on Impairment Method (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Loans individually evaluated for impairment, allowance		$ 6,429
Loans individually evaluated for impairment, balance		95,405
Loans collectively evaluated for impairment, allowance		160,109
Loans collectively evaluated for impairment, balance		15,548,991
Loans, allowance	$ 131,256	166,538
Loans	15,690,689	15,644,396
Commercial Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance		1,030
Loans individually evaluated for impairment, balance		27,070
Loans collectively evaluated for impairment, allowance		67,712
Loans collectively evaluated for impairment, balance		2,809,763
Loans, allowance		68,742
Loans	2,867,437	2,836,833
Real Estate Construction Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance		0
Loans individually evaluated for impairment, balance		4,286
Loans collectively evaluated for impairment, allowance		30,854
Loans collectively evaluated for impairment, balance		675,206
Loans, allowance		30,854
Loans	664,495	679,492
Commercial Real Estate Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance		5,254
Loans individually evaluated for impairment, balance		53,289
Loans collectively evaluated for impairment, allowance		43,951
Loans collectively evaluated for impairment, balance		7,501,738
Loans, allowance		49,205
Loans	7,615,088	7,555,027
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance		145
Loans individually evaluated for impairment, balance		10,760
Loans collectively evaluated for impairment, allowance		17,592
Loans collectively evaluated for impairment, balance		4,559,184
Loans, allowance		17,737
Loans	$ 4,540,537	4,569,944
Consumer Portfolio Segment [Member]
Loans individually evaluated for impairment, allowance		0
Loans individually evaluated for impairment, balance		0
Loans collectively evaluated for impairment, allowance		0
Loans collectively evaluated for impairment, balance		3,100
Loans, allowance		0
Loans		$ 3,100

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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