Note 4 - Investment Securities (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

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

	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

	As of December 31, 2017
			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses		Fair Value
	(In thousands)
Securities Available-for-Sale
U.S. treasury securities	$	249,877	$	-	$	357	$	249,520
U.S. government agency entities		9,047		11		70		8,988
U.S. government sponsored entities		400,000		-		9,664		390,336
State and municipal securities		1,944		-		30		1,914
Mortgage-backed securities		577,987		241		6,259		571,969
Collateralized mortgage obligations		1,533		-		17		1,516
Corporate debt securities		80,007		1,291		17		81,281
Mutual funds		6,500		-		270		6,230
Preferred stock of government sponsored entities		5,842		4,260		-		10,102
Other equity securities		3,608		8,162		-		11,770
Total securities available-for-sale	$	1,336,345	$	13,965	$	16,684	$	1,333,626

Investments Classified by Contractual Maturity Date [Table Text Block]

	Securities Available-for-Sale
	Amortized Cost		Fair Value
	(In thousands)
Due in one year or less	$	124,807	$	124,757
Due after one year through five years		465,813		455,010
Due after five years through ten years		6,078		5,856
Due after ten years		671,033		656,886
Total	$	1,267,731	$	1,242,509

Schedule of Unrealized Loss on Investments [Table Text Block]

	As of December 31, 2018
	Temporarily Impaired Securities
	Less than 12 months						12 months or longer						Total
	Fair		Unrealized		No. of		Fair		Unrealized		No. of		Fair		Unrealized		No. of
	Value		Losses		Issuances		Value		Losses		Issuances		Value		Losses		Issuances
	(Dollars in thousands)
Securities Available-for-Sale
U.S. treasury securities	$	124,751	$	51		4	$	-	$	-		-	$	124,751	$	51		4
U.S. government agency entities		3,388		77		2		2,483		118		2		5,871		195		4
U.S. government sponsored entities		-		-		-		388,362		11,637		8		388,362		11,637		8
Mortgage-backed securities		48,528		502		8		507,701		14,587		74		556,229		15,089		82
Collateralized mortgage obligations		-		-		-		977		28		6		977		28		6
Total securities available-for-sale	$	176,667	$	630		14	$	899,523	$	26,370		90	$	1,076,190	$	27,000		104

	As of December 31, 2017
	Temporarily Impaired Securities
	Less than 12 months						12 months or longer						Total
	Fair		Unrealized		No. of		Fair		Unrealized		No. of		Fair		Unrealized		No. of
	Value		Losses		Issuances		Value		Losses		Issuances		Value		Losses		Issuances
	(Dollars in thousands)
Securities Available-for-Sale
U.S. treasury securities	$	199,823	$	62		4	$	49,697	$	295		2	$	249,520	$	357		6
U.S. government agency entities		5,711		70		3		-		-		-		5,711		70		3
U.S. government sponsored entities		-		-		-		390,336		9,664		8		390,336		9,664		8
State and municipal securities		1,914		30		2		-		-		-		1,914		30		2
Mortgage-backed securities		342,436		3,147		48		178,617		3,112		13		521,053		6,259		61
Collateralized mortgage obligations		1,516		17		5		-		-		-		1,516		17		5
Corporate debt securities		5,015		17		1		-		-		-		5,015		17		1
Mutual funds		-		-		-		6,230		270		1		6,230		270		1
Total securities available-for-sale	$	556,415	$	3,343		63	$	624,880	$	13,341		24	$	1,181,295	$	16,684		87