Note 5 - Loans - Components of Loans in Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Jun. 30, 2026	Dec. 31, 2025	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024
Loans held for investment	$ 21,195,861		$ 20,147,202
Less: Allowance for loan losses	(224,190)	$ (218,896)	(195,911)	$ (186,647)	$ (173,531)	$ (161,765)
Unamortized deferred loan fees, net	(15,523)		(14,903)
Loans held for investment, net	20,956,148		19,936,388
Commercial Portfolio Segment [Member]
Loans held for investment	3,945,390		3,184,556
Less: Allowance for loan losses	(39,674)	(46,374)	(39,123)	(39,071)	(40,842)	(57,796)
Real Estate Construction Portfolio Segment [Member]
Loans held for investment	265,880		337,550
Less: Allowance for loan losses	(11,373)	(15,153)	(6,475)	(6,405)	(5,434)	(8,185)
Commercial Real Estate Portfolio Segment [Member]
Loans held for investment	10,844,794		10,564,744
Less: Allowance for loan losses	(142,977)	(134,102)	(125,665)	(117,798)	(106,773)	(79,597)
Residential Portfolio Segment [Member]
Loans held for investment	5,905,416		5,832,094
Equity Lines Portfolio Segment [Member]
Loans held for investment	227,831		226,444
Installment and Other Loans [Member ]
Loans held for investment	6,550		1,814
Less: Allowance for loan losses	$ (23)	$ (7)	$ (7)	$ (12)	$ (17)	$ (6)