Note 7 - Investment Securities (Tables)

3 Months Ended

Mar. 31, 2024

Notes Tables

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

	March 31, 2024
			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses		Fair Value
	(In thousands)
Securities AFS
U.S. treasury securities	$	541,914	$	4	$	120	$	541,798
U.S. government agency entities		12,123		61		126		12,058
U.S. government sponsored entities		59,785		—		40		59,745
Mortgage-backed securities		871,231		63		117,132		754,162
Collateralized mortgage obligations		30,494		—		3,296		27,198
Corporate debt securities		268,368		34		10,196		258,206
Total	$	1,783,915	$	162	$	130,910	$	1,653,167

	December 31, 2023
			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses		Fair Value
	(In thousands)
Securities AFS
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

Investments Classified by Contractual Maturity Date [Table Text Block]

	March 31, 2024
	Securities AFS
	Amortized Cost		Fair Value
	(In thousands)
Due in one year or less	$	661,864	$	661,135
Due after one year through five years		207,407		198,023
Due after five years through ten years		140,147		131,192
Due after ten years		774,497		662,817
Total	$	1,783,915	$	1,653,167

Unrealized Gain (Loss) on Investments [Table Text Block]

	March 31, 2024
	Less than 12 Months				12 Months or Longer				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
	(In thousands)
Securities AFS
U.S. treasury securities	$	392,376	$	120	$	—	$	—	$	392,376	$	120
U.S. government agency entities		1,471		2		2,524		124		3,995		126
U.S. government sponsored entities		59,745		40		—		—		59,745		40
Mortgage-backed securities		16,923		87		736,362		117,045		753,285		117,132
Collateralized mortgage obligations		—		—		27,198		3,296		27,198		3,296
Corporate debt securities		54,531		469		168,641		9,727		223,172		10,196
Total	$	525,046	$	718	$	934,725	$	130,192	$	1,459,771	$	130,910

	December 31, 2023
	Less than 12 Months				12 Months or Longer				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
	(In thousands)
Securities AFS
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