Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets
Cash and due from banks	$ 97,743	$ 136,735
Federal funds sold and interest-bearing deposits in other banks	492,243	237,265
Total cash and cash equivalents	589,986	374,000
Securities available-for-sale, amortized cost $202,720 and $282,273, respectively	204,182	282,448
Securities held-to-maturity, fair value $3,207,259 and $2,579,103, respectively	3,211,977	2,509,088
Federal Home Loan Bank of Boston, stock at cost	11,594	13,361
Equity securities, amortized cost $1,635 and $1,635, respectively	1,680	1,668
Loans, net:
Total loans, net	2,925,477	2,995,829
Less: allowance for loan losses	34,764	35,486
Net loans	2,890,713	2,960,343
Bank premises and equipment	42,222	39,062
Accrued interest receivable	13,413	13,283
Goodwill	2,714	2,714
Other assets	161,081	162,867
Total assets	7,129,562	6,358,834
Deposits:
Demand deposits	1,203,943	1,103,878
Savings and NOW deposits	2,314,472	1,728,092
Money market accounts	2,337,665	2,074,108
Time deposits	348,296	546,143
Total deposits	6,204,376	5,452,221
Securities sold under agreements to repurchase	269,961	232,090
Other borrowed funds	118,786	177,009
Subordinated debentures	36,083	36,083
Due to broker	0
Other liabilities	97,405	91,022
Total liabilities	6,726,611	5,988,425
Stockholders' Equity
Preferred Stock – $1.00 par value; 100,000 shares authorized; no shares issued and outstanding
Additional paid-in capital	12,292	12,292
Retained earnings	408,700	378,699
Stockholders' equity before adjustment of accumulated other comprehensive income (loss)	426,560	396,559
Unrealized gains on securities available-for-sale, net of taxes	1,062	130
Unrealized losses on securities transferred to held-to-maturity, net of taxes	(830)	(1,221)
Pension liability, net of taxes	(23,841)	(25,059)
Total accumulated other comprehensive loss, net of taxes	(23,609)	(26,150)
Total stockholders' equity	402,951	370,409
Total liabilities and stockholders' equity	7,129,562	6,358,834
Construction and land development [Member]
Loans, net:
Total loans, net	6,358	10,909
Commercial and industrial [Member]
Loans, net:
Total loans, net	1,321,907	1,314,245
Municipal [Member]
Loans, net:
Total loans, net	138,945	137,607
Commercial real estate [Member]
Loans, net:
Total loans, net	729,384	789,836
Residential real estate [Member]
Loans, net:
Total loans, net	466,109	448,436
Consumer and overdrafts [Member]
Loans, net:
Total loans, net	19,549	20,439
Home equity [Member]
Loans, net:
Total loans, net	243,225	274,357
Class A Common Stock [Member]
Stockholders' Equity
Common stock value	3,673	3,656
Total stockholders' equity	3,673	3,656
Class B Common Stock [Member]
Stockholders' Equity
Common stock value	1,895	1,912
Total stockholders' equity	$ 1,895	$ 1,912