Employee Benefits (Schedule of Net Funded (Unfunded) Status) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Qualified Pension Plan [Member]
Change in Benefit Obligation:
Benefit obligation at beginning of period		$ 73,380	$ 80,723
Service cost	[1]	2,037	2,244	$ 2,149
Interest cost	[2]	2,967	2,715	2,673
Actuarial (gain) loss		10,453	(7,830)
Benefits paid		(5,546)	(4,344)
Administrative expenses		(150)	(128)
Benefit obligation at end of period		83,141	73,380	80,723
Change in Plan Assets:
Fair value of plan assets at beginning of period		86,180	87,364
Actual return on plan assets		13,265	288
Employer contributions		0	3,000
Benefits paid		(5,546)	(4,344)
Administrative expenses		(150)	(128)
Fair value of plan assets at end of period		93,749	86,180	87,364
Funded (unfunded) status at end of period		10,608	12,800
Non-Qualified Retirement Plans [Member]
Change in Benefit Obligation:
Benefit obligation at beginning of period		14,626	15,203
Service cost	[1]	126	108	129
Interest cost	[2]	563	475	428
Actuarial (gain) loss		2,028	(252)
Benefits paid		(905)	(908)
Administrative expenses		0	0
Benefit obligation at end of period		16,438	14,626	15,203
Change in Plan Assets:
Fair value of plan assets at beginning of period		0	0
Actual return on plan assets		0	0
Employer contributions		905	908
Benefits paid		(905)	(908)
Administrative expenses		0	0
Fair value of plan assets at end of period		0	0	$ 0
Funded (unfunded) status at end of period		$ (16,438)	$ (14,626)

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

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