Investment Securities (Tables)

3 Months Ended

Mar. 31, 2024

Investments, Debt and Equity Securities [Abstract]

Available for Sale and Held for Maturity Securities

The amortized cost, gross unrealized gains and losses and estimated fair values for available-for-sale and held-to-maturity securities by major security type at March 31, 2024 and December 31, 2023 were as follows (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Fair Value
March 31, 2024
Available-for-sale:
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	234,540	$	—	$	(27,220	)	$	207,320
Obligations of states and political subdivisions		335,350		84		(52,864	)		282,570
Mortgage-backed securities: GSE residential		699,921		854		(119,771	)		581,004
Other securities		72,792		—		(4,259	)		68,533
Total available-for-sale	$	1,342,603	$	938	$	(204,114	)	$	1,139,427
Held-to-maturity:
Other investments	$	2,282	$	—	$	—		$	2,282
Total held-to-maturity	$	2,282	$	—	$	—		$	2,282
December 31, 2023
Available-for-sale:
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	237,875	$	—	$	(26,219	)	$	211,656
Obligations of states and political subdivisions		337,835		152		(49,371	)		288,616
Mortgage-backed securities: GSE residential		714,216		1,158		(113,074	)		602,300
Other securities		73,795		—		(4,795	)		69,000
Total available-for-sale	$	1,363,721	$	1,310	$	(193,459	)	$	1,171,572
Held-to-maturity:
Other investments	$	2,286	$	—	$	—		$	2,286
Total held-to-maturity	$	2,286	$	—	$	—		$	2,286

Realized Gains and Losses From Sale of Securities

Realized gains and losses resulting from sales of securities were as follows during the three months ended March 31, 2024 and 2023 (in thousands):

	Three months ended
	March 31,
	2024		2023
Gross gains	$	—	$	6
Gross losses		—		(52	)

Investments Classified by Contractual Maturity Date

The following table indicates the expected maturities of investment securities classified as available-for-sale presented at fair value, and held-to-maturity presented at amortized cost, at March 31, 2024 and the weighted average yield for each range of maturities (dollars in thousands):

	One year or less			After 1 through 5 years			After 5 through 10 years			After ten years			Total
Available-for-sale:
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	181,730		$	25,590		$	—		$	—		$	207,320
Obligations of state and political subdivisions		21,240			102,416			157,672			1,242			282,570
Mortgage-backed securities: GSE residential		2,280			6,030			33,981			538,713			581,004
Other securities		27,942			39,838			753			—			68,533
Total available-for-sale investments	$	233,192		$	173,874		$	192,406		$	539,955		$	1,139,427
Weighted average yield		1.75	%		2.62	%		2.25	%		1.82	%		2.00	%
Full tax-equivalent yield		1.75	%		2.63	%		2.22	%		1.84	%		2.00	%
Held to maturity:
Other investments	$	—		$	—		$	—		$	2,282		$	2,282
Total held-to-maturity	$	—		$	—		$	—		$	2,282		$	2,282
Weighted average yield		—	%		—	%		—	%		—	%		—	%
Full tax-equivalent yield		—	%		—	%		—	%		—	%		—	%

Fair Value of Investments with Sustained Gross Unrealized Losses

The following table presents the aging of gross unrealized losses and fair value by investment category as of March 31, 2024 and December 31, 2023 (in thousands):

	Less than 12 months					12 months or more					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
March 31, 2024
Available-for-sale:
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	1,295	$	—		$	206,025	$	(27,220	)	$	207,320	$	(27,220	)
Obligations of states and political subdivisions		27,302		(324	)		248,168		(52,540	)		275,470		(52,864	)
Mortgage-backed securities: GSE residential		5,773		(132	)		545,899		(119,639	)		551,672		(119,771	)
Other securities		5,337		(413	)		57,446		(3,846	)		62,783		(4,259	)
Total	$	39,707	$	(869	)	$	1,057,538	$	(203,245	)	$	1,097,245	$	(204,114	)
December 31, 2023
Available-for-sale:
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	1,288	$	(4	)	$	210,069	$	(26,215	)	$	211,357	$	(26,219	)
Obligations of states and political subdivisions		22,281		(333	)		241,630		(49,038	)		263,911		(49,371	)
Mortgage-backed securities: GSE residential		5,818		(67	)		566,197		(113,007	)		572,015		(113,074	)
Other securities		5,311		(439	)		57,939		(4,356	)		63,250		(4,795	)
Total	$	34,698	$	(843	)	$	1,075,835	$	(192,616	)	$	1,110,533	$	(193,459	)