Revenue from Contract with Customer (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Personal trust and agency accounts income	$ 8,761	$ 9,001	$ 8,495
Employee benefit and retirement-related accounts income	7,921	7,178	6,863
Investment management and investment advisory agency accounts income	10,652	10,024	9,352
Other income from fiduciary activities	1,539	1,565	1,583
Non-sufficient funds (NSF) fees	4,999	7,073	7,483
Demand deposit account (DDA) charges	2,920	3,105	3,310
Other service charges on deposit accounts	526	657	668
Credit card other service income	2,112	2,361	2,239
HELOC other service income	424	407	471
Installment other service income	165	173	243
Real estate other service income	32,889	11,158	9,079
Commercial other service income	2,021	1,401	2,234
Debit card fee income	22,160	20,250	17,317
Bank Owned Life Insurance Income	4,789	4,557	6,815
ATM Fees	1,773	1,828	1,978
Gains (Losses) on Sales of Other Real Estate	1,207	(222)	4,235
Debt and Equity Securities, Gain (Loss)	3,286	(421)	(2,271)
Gain on equity securities, net	2,182	5,118	4,616
Other components of net periodic benefit income	7,952	4,732	6,820
Gain (Loss) on Sales of Loans, Net	0	0	2,826
Noninterest Income, Other	7,386	7,248	6,745
Noninterest Income	125,664	97,193	101,101
Bank Servicing [Member]
Disaggregation of Revenue [Line Items]
Noninterest Income, Other	37,600	15,500	14,300
Within Scope [Domain]
Disaggregation of Revenue [Line Items]
Noninterest Income, Other	5,200	4,900	5,500
Out of Scope [Domain]
Disaggregation of Revenue [Line Items]
Noninterest Income, Other	32,400	10,600	8,800
Pnb Segment [Member]
Disaggregation of Revenue [Line Items]
Personal trust and agency accounts income	8,761	9,001	8,495
Employee benefit and retirement-related accounts income	7,921	7,178	6,863
Investment management and investment advisory agency accounts income	10,652	10,024	9,352
Other income from fiduciary activities	1,539	1,565	1,583
Non-sufficient funds (NSF) fees	4,999	7,073	7,483
Demand deposit account (DDA) charges	2,920	3,105	3,310
Other service charges on deposit accounts	526	657	668
Credit card other service income	2,108	2,354	2,212
HELOC other service income	424	403	471
Installment other service income	165	256	243
Real estate other service income	32,827	11,167	9,079
Commercial other service income	1,493	1,259	1,153
Debit card fee income	22,160	20,250	17,317
Bank Owned Life Insurance Income	4,521	4,168	4,903
ATM Fees	1,773	1,828	1,978
Gains (Losses) on Sales of Other Real Estate	836	(110)	1,440
Debt and Equity Securities, Gain (Loss)	3,286	(421)	(2,271)
Gain on equity securities, net	2,429	913	549
Other components of net periodic benefit income	7,759	4,587	6,609
Gain (Loss) on Sales of Loans, Net			660
Noninterest Income, Other	7,132	7,135	6,884
Noninterest Income	124,231	92,392	88,981
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	4	7	27
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
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	94	54	75
Gain (Loss) on Sales of Loans, Net			0
Noninterest Income, Other	157	109	85
Noninterest Income	255	170	187
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	0	4	0
Installment other service income	0	(83)	0
Real estate other service income	62	(9)	0
Commercial other service income	528	142	1,081
Debit card fee income	0	0	0
Bank Owned Life Insurance Income	268	389	1,912
ATM Fees	0	0	0
Gains (Losses) on Sales of Other Real Estate	371	(112)	2,795
Debt and Equity Securities, Gain (Loss)	0	0	0
Gain on equity securities, net	(247)	4,205	4,067
Other components of net periodic benefit income	99	91	136
Gain (Loss) on Sales of Loans, Net			2,166
Noninterest Income, Other	97	4	(224)
Noninterest Income	$ 1,178	$ 4,631	$ 11,933