INVESTMENTS (Tables)

12 Months Ended

Dec. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Amortized cost and Estimated fair values of Investments Available-for-sale

The amortized cost and estimated fair values of investments available-for-sale at December 31 are presented in the following table:

	2020								2019
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
U.S. treasuries and government agencies	$	42,750	$	549	$	(2)	$	43,297	$	260,294	$	887	$	(2,686)	$	258,495
State and municipal	377,108		13,470		(211)		390,367		229,309		4,377		(37)		233,649
Mortgage-backed and asset-backed	881,201		24,078		(847)		904,432		568,373		3,268		(882)		570,759
Corporate debt	9,100		825		—		9,925		9,100		452		—		9,552
Trust preferred	—		—		—		—		310		—		—		310
Total debt securities	1,310,159		38,922		(1,060)		1,348,021		1,067,386		8,984		(3,605)		1,072,765
Marketable equity securities	—		—		—		—		568		—		—		568
Total investments available-for-sale	$	1,310,159	$	38,922	$	(1,060)	$	1,348,021	$	1,067,954	$	8,984	$	(3,605)	$	1,073,333

Gross Unrealized Losses and Fair Value by Length of Time

Gross unrealized losses and fair values by length of time that individual available-for-sale securities have been in an unrealized loss position at December 31 are presented in the following tables:

	December 31, 2020
	Number of Securities	Less Than 12 Months				12 Months or More				Total
(Dollars in thousands)		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. treasuries and government agencies	2	$	25,369	$	2	$	—	$	—	$	25,369	$	2
State and municipal	8	22,753		211		—		—		22,753		211
Mortgage-backed and asset-backed	24	44,746		154		76,879		693		121,625		847
Total	34	$	92,868	$	367	$	76,879	$	693	$	169,747	$	1,060

	December 31, 2019
	Number of Securities	Less Than 12 Months				12 Months or More				Total
(Dollars in thousands)		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. treasuries and government agencies	12	$	133,221	$	2,211	$	17,911	$	475	$	151,132	$	2,686
State and municipal	3	7,227		37		—		—		7,227		37
Mortgage-backed and asset-backed	35	107,917		508		76,867		374		184,784		882
Total	50	$	248,365	$	2,756	$	94,778	$	849	$	343,143	$	3,605

Estimated fair values of debt securities available-for-sale by contractual maturity

The estimated fair values and amortized costs of debt securities available-for-sale by contractual maturity at December 31 are provided in the following table:

	December 31, 2020				December 31, 2019
(In thousands)	Fair Value		Amortized Cost		Fair Value		Amortized Cost
U.S. treasuries and government agencies:
One year or less	$	33,963	$	33,833	$	69,799	$	69,330
One to five years	9,334		8,917		96,709		96,507
Five to ten years	—		—		—		—
After ten years	—		—		91,987		94,457
State and municipal:
One year or less	16,581		16,458		33,311		33,054
One to five years	44,910		43,857		76,723		75,432
Five to ten years	59,059		56,130		75,820		73,741
After ten years	269,817		260,663		47,795		47,082
Mortgage-backed and asset-backed:
One year or less	1		1		852		822
One to five years	21,637		21,229		7,125		6,969
Five to ten years	74,142		72,481		55,226		54,799
After ten years	808,652		787,490		507,556		505,783
Corporate debt:
One year or less	—		—		—		—
One to five years	2,318		2,100		—		—
Five to ten years	7,607		7,000		9,552		9,100
After ten years	—		—		—		—
Trust preferred:
One year or less	—		—		—		—
One to five years	—		—		—		—
Five to ten years	—		—		—		—
After ten years	—		—		310		310
Total available-for-sale debt securities	$	1,348,021	$	1,310,159	$	1,072,765	$	1,067,386

Other Equity Securities

Other equity securities at the dates indicated are presented in the following table:

(In thousands)	2020		2019
Federal Reserve Bank stock	$	38,650	$	22,559
Federal Home Loan Bank of Atlanta stock	26,433		29,244
Other equity securities	677		—
Total equity securities	$	65,760	$	51,803

Gross Realized Gains and Losses on All Investments

Gross realized gains and losses on all investments for the years ended December 31 are presented in the following table:

(In thousands)	2020		2019		2018
Gross realized gains from sales of investments available-for-sale	$	1,297	$	14	$	2,519
Gross realized losses from sales of investments available-for-sale	(1,068)		(2)		(2,343)
Net gains from calls of investments available-for-sale	238		65		14
Net investment securities gains	$	467	$	77	$	190