Note 3 - Investment Securities (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

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

	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

	As of December 31, 2018
			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses		Fair Value
	(In thousands)
Securities Available-for-Sale
U.S. treasury securities	$	124,801	$	—	$	50	$	124,751
U.S. government agency entities		6,066		—		195		5,871
U.S. government sponsored entities		400,000		—		11,638		388,362
Mortgage-backed securities		670,874		960		15,089		656,745
Collateralized mortgage obligations		1,005		—		28		977
Corporate debt securities		64,985		818		—		65,803
Total securities available-for-sale	$	1,267,731	$	1,778	$	27,000	$	1,242,509

Investments Classified by Contractual Maturity Date [Table Text Block]

	Securities Available-for-Sale
	As of December 31, 2019
	Amortized Cost		Fair Value
	(In thousands)
Due in one year or less	$	168,831	$	168,894
Due after one year through five years		304,348		304,337
Due after five years through ten years		50,587		50,593
Due after ten years		919,964		928,018
Total	$	1,443,730	$	1,451,842

Schedule of Unrealized Loss on Investments [Table Text Block]

	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

	As of December 31, 2018
	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	$	124,751	$	51	$	—	$	—	$	124,751	$	51
U.S. government agency entities		3,388		77		2,483		118		5,871		195
U.S. government sponsored entities		—		—		388,362		11,637		388,362		11,637
Mortgage-backed securities		48,528		502		507,701		14,587		556,229		15,089
Collateralized mortgage obligations		—		—		977		28		977		28
Total securities available-for-sale	$	176,667	$	630	$	899,523	$	26,370	$	1,076,190	$	27,000