Revenue from Contract with Customer (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Personal trust and agency accounts income	$ 9,001	$ 8,495	$ 7,752
Employee benefit and retirement-related accounts income	7,178	6,863	6,234
Investment management and investment advisory agency accounts income	10,024	9,352	8,386
Other income from fiduciary activities	1,565	1,583	1,363
Non-sufficient funds (NSF) fees	7,073	7,483	8,122
Demand deposit account (DDA) charges	3,105	3,310	3,847
Other service charges on deposit accounts	657	668	684
Credit card other service income	2,361	2,239	1,981
HELOC other service income	407	471	478
Installment other service income	173	243	387
Real estate other service income	11,158	9,079	9,005
Commercial other service income	1,401	2,234	1,311
Debit card fee income	20,250	17,317	15,798
Bank Owned Life Insurance Income	4,557	6,815	4,858
ATM Fees	1,828	1,978	2,253
OREO devaluations	225	491	458
Gains (Losses) on Sales of Other Real Estate	(222)	4,235	251
Debt and Equity Securities, Gain (Loss)	(421)	(2,271)	1,821
Gain on equity securities, net	5,118	4,616	1,210
Other components of net periodic benefit income	4,732	6,820	5,794
Noninterest Income, Other	7,473	7,236	5,352
Noninterest Income	97,193	101,101	86,429
Gain (Loss) on Sales of Loans, Net	0	2,826	0
Bank Servicing [Member]
Disaggregation of Revenue [Line Items]
Noninterest Income, Other	15,500	14,300	13,200
Within Scope [Domain]
Disaggregation of Revenue [Line Items]
Noninterest Income, Other	4,900	5,500	4,400
Out of Scope [Domain]
Disaggregation of Revenue [Line Items]
Noninterest Income, Other	10,600	8,800	8,800
Pnb Segment [Member]
Disaggregation of Revenue [Line Items]
Personal trust and agency accounts income	9,001	8,495	7,752
Employee benefit and retirement-related accounts income	7,178	6,863	6,234
Investment management and investment advisory agency accounts income	10,024	9,352	8,386
Other income from fiduciary activities	1,565	1,583	1,363
Non-sufficient funds (NSF) fees	7,073	7,483	8,122
Demand deposit account (DDA) charges	3,105	3,310	3,847
Other service charges on deposit accounts	657	668	684
Credit card other service income	2,354	2,212	1,987
HELOC other service income	403	471	474
Installment other service income	256	243	387
Real estate other service income	11,167	9,079	8,974
Commercial other service income	1,259	1,153	1,118
Debit card fee income	20,250	17,317	15,798
Bank Owned Life Insurance Income	4,168	4,903	4,441
ATM Fees	1,828	1,978	2,253
OREO devaluations	225	272	458
Gains (Losses) on Sales of Other Real Estate	(110)	1,440	239
Debt and Equity Securities, Gain (Loss)	(421)	(2,271)	0
Gain on equity securities, net	913	549	11
Other components of net periodic benefit income	4,587	6,609	5,616
Noninterest Income, Other	7,360	7,156	5,514
Noninterest Income	92,392	88,981	82,742
Gain (Loss) on Sales of Loans, Net		660
GFSC [Member]
Disaggregation of Revenue [Line Items]
Personal trust and agency accounts income	0	0	0
Employee benefit and retirement-related accounts income	0	0	0
Investment management and investment advisory agency accounts income	0	0	0
Other income from fiduciary activities	0	0	0
Non-sufficient funds (NSF) fees	0	0	0
Demand deposit account (DDA) charges	0	0	0
Other service charges on deposit accounts	0	0	0
Credit card other service income	7	27	(6)
HELOC other service income	0	0	0
Installment other service income	0	0	0
Real estate other service income	0	0	0
Commercial other service income	0	0	0
Debit card fee income	0	0	0
Bank Owned Life Insurance Income	0	0	0
ATM Fees	0	0	0
OREO devaluations	0	0	0
Gains (Losses) on Sales of Other Real Estate	0	0	0
Debt and Equity Securities, Gain (Loss)	0	0	0
Gain on equity securities, net	0	0	0
Other components of net periodic benefit income	54	75	63
Noninterest Income, Other	109	85	46
Noninterest Income	170	187	103
Gain (Loss) on Sales of Loans, Net		0
Other Segments [Member]
Disaggregation of Revenue [Line Items]
Personal trust and agency accounts income	0	0	0
Employee benefit and retirement-related accounts income	0	0	0
Investment management and investment advisory agency accounts income	0	0	0
Other income from fiduciary activities	0	0	0
Non-sufficient funds (NSF) fees	0	0	0
Demand deposit account (DDA) charges	0	0	0
Other service charges on deposit accounts	0	0	0
Credit card other service income	0	0	0
HELOC other service income	4	0	4
Installment other service income	(83)	0	0
Real estate other service income	(9)	0	31
Commercial other service income	142	1,081	193
Debit card fee income	0	0	0
Bank Owned Life Insurance Income	389	1,912	417
ATM Fees	0	0	0
OREO devaluations	0	219	0
Gains (Losses) on Sales of Other Real Estate	(112)	2,795	12
Debt and Equity Securities, Gain (Loss)	0	0	1,821
Gain on equity securities, net	4,205	4,067	1,199
Other components of net periodic benefit income	91	136	115
Noninterest Income, Other	4	(5)	(208)
Noninterest Income	$ 4,631	11,933	$ 3,584
Gain (Loss) on Sales of Loans, Net		$ 2,166