Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Personal trust and agency accounts	$ 2,171	$ 2,301
Employee benefit and retirement-related accounts	1,916	1,670
Investment management and investment advisory agency accounts	2,642	2,381
Other	384	371
Non-sufficient funds (NSF) fees	1,615	1,616
Demand deposit account (DDA) charges	761	780
Other	152	163
Credit card	597	600
HELOC	98	99
Installment	53	70
Real estate	2,647	1,757
Commercial	371	292
Debit card fee income	4,960	4,369
Bank owned life insurance income	1,248	1,006
ATM Fees	412	440
Gains (Losses) on Sales of Other Real Estate	(196)	(12)
Loss (gain) on equity securities, net	(973)	1,742
Other components of net periodic benefit income	1,988	1,183
Other	1,640	1,197
Total other income	22,486	22,025
Bank Servicing [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3,766	2,818
Within Scope [Domain]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	2,300	1,200
Out of Scope [Domain]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,500	1,600
PNB [Member]
Disaggregation of Revenue [Line Items]
Personal trust and agency accounts	2,171	2,301
Employee benefit and retirement-related accounts	1,916	1,670
Investment management and investment advisory agency accounts	2,642	2,381
Other	384	371
Non-sufficient funds (NSF) fees	1,615	1,616
Demand deposit account (DDA) charges	761	780
Other	152	163
Credit card	596	597
HELOC	98	95
Installment	53	74
Real estate	2,647	1,757
Commercial	371	292
Debit card fee income	4,960	4,369
Bank owned life insurance income	1,166	898
ATM Fees	412	440
Gains (Losses) on Sales of Other Real Estate	(196)	(12)
Loss (gain) on equity securities, net	166	589
Other components of net periodic benefit income	1,940	1,147
Other	1,627	1,180
Total other income	23,481	20,708
GFSC [Member]
Disaggregation of Revenue [Line Items]
Personal trust and agency accounts	0	0
Employee benefit and retirement-related accounts	0	0
Investment management and investment advisory agency accounts	0	0
Other	0	0
Non-sufficient funds (NSF) fees	0	0
Demand deposit account (DDA) charges	0	0
Other	0	0
Credit card	1	3
HELOC	0	0
Installment	0	0
Real estate	0	0
Commercial	0	0
Debit card fee income	0	0
Bank owned life insurance income	0	0
ATM Fees	0	0
Gains (Losses) on Sales of Other Real Estate	0	0
Loss (gain) on equity securities, net	0	0
Other components of net periodic benefit income	24	13
Other	7	16
Total other income	32	32
All Other [Member]
Disaggregation of Revenue [Line Items]
Personal trust and agency accounts	0	0
Employee benefit and retirement-related accounts	0	0
Investment management and investment advisory agency accounts	0	0
Other	0	0
Non-sufficient funds (NSF) fees	0	0
Demand deposit account (DDA) charges	0	0
Other	0	0
Credit card	0	0
HELOC	0	4
Installment	0	(4)
Real estate	0	0
Commercial	0	0
Debit card fee income	0	0
Bank owned life insurance income	82	108
ATM Fees	0	0
Gains (Losses) on Sales of Other Real Estate	0	0
Loss (gain) on equity securities, net	(1,139)	1,153
Other components of net periodic benefit income	24	23
Other	6	1
Total other income	$ (1,027)	$ 1,285