Other Comprehensive Income (Loss) (Activity in Other Comprehensive Income) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Change in fair value of securities available for sale, before tax		$ (163,471)		$ (21,942)		$ 8,784
Change in fair value of securities available for sale, tax		39,233		5,266		(2,129)
Change is fair value of securities available for sale		(124,238)		(16,676)		6,655
Change in fair value of cash flow hedges, before tax		(27,344)		(3,067)		(2,003)
Change in fair value of cash flow hedges, tax		6,563		736		482
Change in fair value of cash flow hedges		(20,781)		(2,331)		(1,521)
Net gains on cash flow hedges reclassified into earnings, before tax		2,828	[1]	(310)	[2]	1,136	[3]
Net gains on cash flow hedges reclassified into earnings, tax		(679)	[1]	75	[2]	(269)	[3]
Net gains on cash flow hedges reclassified into earnings		2,149	[1]	(235)	[2]	867	[3]
Net change in the fair value of cash flow hedges, before tax		(24,516)		(3,377)		(867)
Net change in the fair value of cash flow hedges, tax		5,884		811		213
Net change in fair value of cash flow hedges		(18,632)		(2,566)		(654)
Defined benefit plan obligation adjustment, before tax		4,934		5,908		(5,093)
Defined benefit plan obligation adjustment, tax		(1,184)		(1,417)		1,197
Defined benefit plan obligation adjustment		3,750		4,491		(3,896)
Amortization of net actuarial losses, before tax	[4]	1,712		2,844		2,141
Amortization of net actuarial losses, tax	[4]	(411)		(683)		(400)
Amortization of net actuarial losses	[4]	1,301		2,161		1,741
Recognized in other comprehensive income (loss)		6,646		8,752		(2,952)
Net change in defined benefit plan obligations, tax		(1,595)		(2,100)		797
Net change in defined benefit plan obligations		5,051		6,652		(2,155)
Total other comprehensive income (loss), before tax		(181,341)		(16,567)		4,965
Total other comprehensive income (loss), tax		43,522		3,977		(1,119)
Total other comprehensive income (loss), net of tax		(137,819)		(12,590)		3,846
Junior Subordinated Debt [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Net gains on cash flow hedges reclassified into earnings, before tax						116
Federal Home Loan Bank of Boston [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Net gains on cash flow hedges reclassified into earnings, before tax		70		1,100		817
Interest Income [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Net gains on cash flow hedges reclassified into earnings, before tax		$ 2,800		$ (1,500)		$ 203

[1] The pre-tax amounts reclassified into earnings in the Consolidated Statements of Income include a $2.8 million reduction in interest and fees on loans and a $70 thousand increase in FHLB interest expense.

[2] The pre-tax amounts reclassified into earnings in the Consolidated Statements of Income include a $1.5 million increase in interest and fees on loans and a $1.1 million increase in FHLB interest expense.

[3] The pre-tax amounts reclassified into earnings in the Consolidated Statements of Income include a $203 thousand reduction in interest and fees on loans, $817 thousand increase in FHLB interest expense and a $116 thousand increase in junior subordinated debentures interest expense.

[4] The pre-tax amount presented above is included in other expenses in the Consolidated Statements of Income.