Note 4 - Investment Securities

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]

4.         Investment Securities

Investment Securities. The following tables reflect the amortized cost, gross unrealized gains, gross unrealized losses, and fair values of debt securities available-for-sale as of December 31, 2023 and December 31, 2022:

	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

The amortized cost and fair value of securities available-for-sale as of December 31, 2023, by contractual maturities, are set forth in the table below. Actual maturities may differ from contractual maturities because borrowers may have the right to call or repay obligations with or without call or repayment penalties.  

	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

There were no sales of investment securities during the years ended December 31, 2023 and 2022. We received proceeds of $21.1 million from sales of investment securities for the year ended December 31, 2021.  Gross realized gain on sale of investment securities was $853 thousand for the year ended December 31, 2021.

Allowance for Credit Losses

The securities that were in an unrealized loss position as of December 31, 2023, were evaluated to determine whether the decline in fair value below the amortized cost basis resulted from a credit loss or other factors. For a discussion of the factors and criteria the Company uses in analyzing securities for impairment related to credit losses, see Note 1 Summary of Significant Accounting Policies - Allowance for Credit Losses on Available for Sale Securities to the Consolidated Financial Statements.

The Company concluded the unrealized losses were primarily attributed to yield curve movement, together with widened liquidity spreads and credit spreads. The issuers have not, to the Company’s knowledge, established any cause for default on these securities. The Company expects to recover the amortized cost basis of its securities and has no present intent to sell and will not be required to sell available-for-sale securities that have declined below their cost before their anticipated recovery. Accordingly, no allowance for credit losses was recorded as of December 31, 2023 and 2022, against these securities, and there was no provision for credit losses recognized for the years ended December 31, 2023, 2022 and 2021.

The tables below show the related fair value and the gross unrealized losses of the Company’s investment portfolio, aggregated by investment category and the length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2023, and December 31, 2022:

	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

As of December 31, 2023 the Company had 192 AFS debt securities in a gross unrealized loss position with no credit impairment, consisting of 154 mortgage-backed securities, 24 corporate debt securities, one U.S. treasury securities, five collateralized mortgage obligations and eight U.S. government agencies.  In comparison, as of December 31, 2022, the Company had 159 mortgage-backed securities, 22 corporate debt securities, six U.S. treasury securities, five collateralized mortgage obligations and three U.S. government agencies.

Securities available-for-sale having a carrying value of $134.2 million and $145.7 million as of December 31, 2023, and December 31, 2022, respectively, were pledged to secure public deposits, and other borrowings.

Equity securities were $40.4 million and $22.2 million as of December 31, 2023 and 2022, respectively. The Company recognized a net unrealized gain of $18.2 million, $291 thousand and $1.4 million for the years ended December 31, 2023, 2022 and 2021, respectively.  The Company received proceeds of $553 thousand and realized a loss of $101 thousand on the sale of equity securities for the year ended December 31, 2022.