Employee Benefits (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) (on a pre-tax basis):
Net loss (gain)		$ 3,710	$ (3,098)	$ 1,591
Prior service credit	[1]	(12)	(18)	(15)
Recognized in other comprehensive income (loss)		(2,526)	4,981	(154)
Qualified Pension Plan [Member]
Net Periodic Benefit Cost:
Service cost	[2]	2,037	2,244	2,149
Interest cost	[3]	2,967	2,715	2,673
Expected return on plan assets	[3]	(4,495)	(5,272)	(4,942)
Amortization of prior service credit	[3]	(16)	(23)	(23)
Recognized net actuarial loss	[3]	792	1,496	1,114
Net periodic benefit cost		1,285	1,160	971
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) (on a pre-tax basis):
Net loss (gain)		890	(4,342)	(1,798)
Prior service credit		16	23	23
Recognized in other comprehensive income (loss)		906	(4,319)	(1,775)
Total recognized in net periodic benefit cost and other comprehensive income (loss)		2,191	(3,159)	(804)
Non-Qualified Retirement Plans [Member]
Net Periodic Benefit Cost:
Service cost	[2]	126	108	129
Interest cost	[3]	563	475	428
Expected return on plan assets	[3]	0	0	0
Amortization of prior service credit	[3]	0	(1)	(1)
Recognized net actuarial loss	[3]	408	411	347
Net periodic benefit cost		1,097	993	903
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) (on a pre-tax basis):
Net loss (gain)		1,620	(663)	1,928
Prior service credit		0	1	1
Recognized in other comprehensive income (loss)		1,620	(662)	1,929
Total recognized in net periodic benefit cost and other comprehensive income (loss)		$ 2,717	$ 331	$ 2,832

[1] The pre-tax amounts are included in other expenses in the Consolidated Statements of Income.

[2] Included in salaries and employee benefits expense in the Consolidated Statements of Income.

[3] Included in other expenses in the Consolidated Statements of Income.