CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
INTEREST AND DIVIDEND INCOME:
Loans, including related fees	$ 124,788	$ 100,541	$ 91,100
Securities:
Taxable	15,191	16,942	14,325
Tax-exempt	7,674	7,455	7,391
Other	1,468	1,286	1,379
TOTAL INTEREST AND DIVIDEND INCOME	149,121	126,224	114,195
INTEREST EXPENSE:
Deposits	15,711	9,032	6,011
Short-term borrowings	1,105	501	245
Other borrowings	653	112	82
TOTAL INTEREST EXPENSE	17,469	9,645	6,338
NET INTEREST INCOME	131,652	116,579	107,857
Provision for loan losses	4,700	5,768	5,295
NET INTEREST INCOME AFTER PROVISION FOR LOAN LOSSES	126,952	110,811	102,562
Trust And Financial Services Revenue	5,036	5,286	5,001
Service Charges And Fees On Deposit Accounts	11,795	11,733	11,895
Service Charges And Fees, Other	14,012	13,012	12,499
NON-INTEREST INCOME:
Securities gain (loss), net	44	2	59
Insurance commissions	133	144	74
Gain on Sale of certain assets and liabilities of Insurance Brokerage Operation	0	0	0
Gain on sale of mortgage loans	2,573	1,829	1,688
Other	4,859	6,200	4,722
TOTAL NON-INTEREST INCOME	38,452	38,206	35,938
Labor and Related Expense	54,827	50,658	50,116
NON-INTEREST EXPENSES:
Occupancy expense	7,600	7,030	6,897
Equipment expense	8,244	6,827	7,186
Federal Deposit Insurance	693	929	915
Other	33,041	25,845	23,633
TOTAL NON-INTEREST EXPENSE	104,405	91,289	88,747
INCOME BEFORE INCOME TAXES	60,999	57,728	49,753
Provision for income taxes	12,127	11,145	20,622
NET INCOME	48,872	46,583	29,131
OTHER COMPREHENSIVE INCOME
Change in unrealized gains/losses on securities, net of reclassifications and taxes	20,998	(8,861)	3,335
Change in funded status of post-retirement benefits, net of taxes	(5,045)	2,477	(3,875)
COMPREHENSIVE INCOME	$ 64,825	$ 40,199	$ 28,591
EARNINGS PER SHARE:
BASIC AND DILUTED (in dollars per share)	$ 3.80	$ 3.80	$ 2.38
Weighted average number of shares outstanding (in shares)	12,865	12,256	12,225