Note 4 - Investment Securities (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Schedule of Available-for-Sale Securities Reconciliation [Table Text Block]

	As of December 31, 2023
			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses		Fair Value
	(In thousands)
Securities Available-for-Sale
U.S. treasury securities	$	495,167	$	153	$	20	$	495,300
U.S. government agency entities		48,282		117		230		48,169
Mortgage-backed securities		892,942		223		106,442		786,723
Collateralized mortgage obligations		31,238		—		3,194		28,044
Corporate debt securities		258,451		22		12,139		246,334
Total	$	1,726,080	$	515	$	122,025	$	1,604,570

	As of December 31, 2022
			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses		Fair Value
	(In thousands)
Securities Available-for-Sale
U.S. treasury securities	$	241,611	$	—	$	1,111	$	240,500
U.S. government agency entities		63,347		384		121		63,610
U.S. government sponsored entities		30,000		—		—		30,000
Mortgage-backed securities		993,883		194		126,983		867,094
Collateralized mortgage obligations		34,552		—		3,491		31,061
Corporate debt securities		258,780		112		17,809		241,083
Total	$	1,622,173	$	690	$	149,515	$	1,473,348

Investments Classified by Contractual Maturity Date [Table Text Block]

	Securities Available-for-Sale
	As of December 31, 2023
	Amortized Cost		Fair Value
	(In thousands)
Due in one year or less	$	525,406	$	524,948
Due after one year through five years		227,132		215,834
Due after five years through ten years		149,042		141,044
Due after ten years		824,500		722,744
Total	$	1,726,080	$	1,604,570

Gain (Loss) on Securities [Table Text Block]

	As of December 31, 2023
	Less than 12 months				12 months or longer				Total
	Fair		Gross Unrealized		Fair		Gross Unrealized		Fair		Gross Unrealized
	Value		Losses		Value		Losses		Value		Losses
	(In thousands)
Securities Available-for-Sale
U.S. treasury securities	$	49,831	$	20	$	—	$	—	$	49,831	$	20
U.S. government agency entities		18,301		108		1,313		122		19,614		230
Mortgage-backed securities		—		—		768,274		106,442		768,274		106,442
Collateralized mortgage obligations		—		—		28,044		3,194		28,044		3,194
Corporate debt securities		64,448		552		166,864		11,587		231,312		12,139
Total	$	132,580	$	680	$	964,495	$	121,345	$	1,097,075	$	122,025

	As of December 31, 2022
	Less than 12 months				12 months or longer				Total
	Fair		Gross Unrealized		Fair		Gross Unrealized		Fair		Gross Unrealized
	Value		Losses		Value		Losses		Value		Losses
	(In thousands)
Securities Available-for-Sale
U.S. treasury securities	$	240,500	$	1,111	$	—	$	—	$	240,500	$	1,111
U.S. government agency entities		—		—		1,806		121		1,806		121
Mortgage-backed securities		394,123		33,042		452,739		93,941		846,862		126,983
Collateralized mortgage obligations		24,427		1,614		6,634		1,877		31,061		3,491
Corporate debt securities		109,995		3,256		100,977		14,553		210,972		17,809
Total	$	769,045	$	39,023	$	562,156	$	110,492	$	1,331,201	$	149,515