Note 3 - Investment Securities (Tables)

12 Months Ended

Dec. 31, 2020

Notes Tables

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

	As of December 31, 2020
			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses		Fair Value
	(In thousands)
Securities Available-for-Sale
U.S. treasury securities	$	80,948	$	6	$	6	$	80,948
U.S. government agency entities		99,944		441		546		99,839
Mortgage-backed securities		709,709		17,965		606		727,068
Collateralized mortgage obligations		10,358		—		34		10,324
Corporate debt securities		118,271		367		267		118,371
Total securities available-for-sale	$	1,019,230	$	18,779	$	1,459	$	1,036,550

	As of December 31, 2019
			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses		Fair Value
	(In thousands)
Securities Available-for-Sale
U.S. treasury securities	$	74,926	$	10	$	—	$	74,936
U.S. government agency entities		90,452		663		319		90,796
U.S. government sponsored entities		225,000		—		557		224,443
Mortgage-backed securities		880,040		8,574		824		887,790
Collateralized mortgage obligations		569		—		17		552
Corporate debt securities		172,743		605		23		173,325
Total securities available-for-sale	$	1,443,730	$	9,852	$	1,740	$	1,451,842

Investments Classified by Contractual Maturity Date [Table Text Block]

	Securities Available-for-Sale
	As of December 31, 2020
	Amortized Cost		Fair Value
	(In thousands)
Due in one year or less	$	131,974	$	132,026
Due after one year through five years		54,820		54,688
Due after five years through ten years		190,440		194,029
Due after ten years		641,996		655,807
Total	$	1,019,230	$	1,036,550

Schedule of Unrealized Loss on Investments [Table Text Block]

	As of December 31, 2020
	Temporarily Impaired Securities
	Less than 12 months				12 months or longer				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
	(In thousands)
Securities Available-for-Sale
U.S. treasury securities	$	40,952	$	6	$	—	$	—	$	40,952	$	6
U.S. government agency entities		26,390		102		40,009		444		66,399		546
Mortgage-backed securities		1,694		23		8,093		583		9,787		606
Collateralized mortgage obligations		10,131		25		193		9		10,324		34
Corporate debt securities		58,405		267		—		—		58,405		267
Total securities available-for-sale	$	137,572	$	423	$	48,295	$	1,036	$	185,867	$	1,459

	As of December 31, 2019
	Temporarily Impaired Securities
	Less than 12 months				12 months or longer				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
	(In thousands)
Securities Available-for-Sale
U.S. government agency entities	$	48,829	$	172	$	3,570	$	147	$	52,399	$	319
U.S. government sponsored entities		—		—		224,443		557		224,443		557
Mortgage-backed securities		43,719		36		120,801		788		164,520		824
Collateralized mortgage obligations		—		—		552		17		552		17
Corporate debt securities		51,791		23		—		—		51,791		23
Total securities available-for-sale	$	144,339	$	231	$	349,366	$	1,509	$	493,705	$	1,740