INVESTMENTS (Tables)

3 Months Ended

Mar. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Costs and Estimated Fair Values of Available-For-Sale Securities

The following table summarizes the amortized cost and estimated fair values of AFS and HTM securities, as of the dates indicated: 

	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
March 31, 2019
AFS Investments (carried at fair value):
Obligations of states and political subdivisions	$	92,030	$	1,095	$	(105	)	$	93,020
Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises	453,980		1,290		(6,449		)	448,821
Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises	366,727		1,888		(7,215		)	361,400
Subordinated corporate bonds	20,398		672		—			21,070
Total AFS investments	$	933,135	$	4,945	$	(13,769	)	$	924,311
HTM Investments (carried at amortized cost):
Obligations of states and political subdivisions	$	1,306	$	21	$	(3	)	$	1,324
Total HTM investments	$	1,306	$	21	$	(3	)	$	1,324
December 31, 2018
AFS Investments (carried at fair value):
Obligations of states and political subdivisions	$	94,430	$	216	$	(894	)	$	93,752
Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises	466,613		583		(13,524		)	453,672
Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises	351,958		1,007		(10,071		)	342,894
Subordinated corporate bonds	20,398		23		(47		)	20,374
Total AFS investments	$	933,399	$	1,829	$	(24,536	)	$	910,692
HTM Investments (carried at amortized cost):
Obligations of states and political subdivisions	$	1,307	$	8	$	(24	)	$	1,291
Total HTM investments	$	1,307	$	8	$	(24	)	$	1,291

The following table summarizes the cost and estimated fair values of the Company's investment in equity securities, FHLBB stock and FRBB stock as presented within other investments on the consolidated statements of condition, as of the dates indicated: 

	Cost		Unrealized Gains		Unrealized Losses		Fair Value / Carrying Value
March 31, 2019
Equity securities - bank stock (carried at fair value)	$	544	$	444	$	—	$	988
FHLBB (carried at cost)	4,880		—		—		4,880
FRB (carried at cost)	5,374		—		—		5,374
Total other investments	$	10,798	$	444	$	—	$	11,242
December 31, 2018
Equity securities - bank stock (carried at fair value)	$	544	$	202	$	—	$	746
FHLBB (carried at cost)	8,559		—		—		8,559
FRB (carried at cost)	5,374		—		—		5,374
Total other investments	$	14,477	$	202	$	—	$	14,679

Unrealized Gross Losses and Estimated Fair Values of Investment Securities by Length of Time that Individual Securities in Each Category in Continuous Loss Position

The following table presents the estimated fair values and gross unrealized losses on AFS and HTM investments that were in a continuous loss position at March 31, 2019 and December 31, 2018, by length of time that an individual security in each category has been in a continuous loss position:  

	Less Than 12 Months					12 Months or More					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
March 31, 2019
AFS Investments:
Obligations of states and political subdivisions	$	2,017	$	—		$	9,941	$	(105	)	$	11,958	$	(105	)
Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises	8,859		(46		)	347,541		(6,403		)	356,400		(6,449		)
Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises	—		—			224,959		(7,215		)	224,959		(7,215		)
Total AFS investments	$	10,876	$	(46	)	$	582,441	$	(13,723	)	$	593,317	$	(13,769	)
HTM Investments:
Obligations of states and political subdivisions	$	—	$	—		$	426	$	(3	)	$	426	$	(3	)
Total HTM investments	$	—	$	—		$	426	$	(3	)	$	426	$	(3	)
December 31, 2018
AFS Investments:
Obligations of states and political subdivisions	$	36,218	$	(281	)	$	28,437	$	(613	)	$	64,655	$	(894	)
Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises	46,459		(252		)	364,430		(13,272		)	410,889		(13,524		)
Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises	5,956		(40		)	227,461		(10,031		)	233,417		(10,071		)
Subordinated corporate bonds	11,378		(26		)	966		(21		)	12,344		(47		)
Total AFS investments	$	100,011	$	(599	)	$	621,294	$	(23,937	)	$	721,305	$	(24,536	)
HTM Investments:
Obligations of states and political subdivisions	$	509	$	(5	)	$	411	$	(19	)	$	920	$	(24	)
Total HTM investments	$	509	$	(5	)	$	411	$	(19	)	$	920	$	(24	)

Schedule of Sale of AFS Investments

Amortized Cost and Estimated Fair Values of Debt Securities by Contractual Maturity

The amortized cost and estimated fair values of the Company's AFS and HTM investments by contractual maturity at March 31, 2019, are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. 

	Amortized Cost		Fair Value
AFS Investments
Due in one year or less	$	14,702	$	14,669
Due after one year through five years	68,822		67,998
Due after five years through ten years	241,455		240,454
Due after ten years	608,156		601,190
	$	933,135	$	924,311
HTM Investments
Due in one year or less	$	—	$	—
Due after one year through five years	—		—
Due after five years through ten years	1,306		1,324
Due after ten years	—		—
	$	1,306	$	1,324