Employee Benefits (Schedule of Net Funded (Unfunded) Status) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Qualified Pension Plan [Member]
Change in Benefit Obligation:
Benefit obligation at beginning of period		$ 83,141	$ 73,380
Service cost	[1]	2,164	2,037	$ 2,244
Interest cost	[2]	2,505	2,967	2,715
Actuarial (gain) loss		10,378	10,453
Benefits paid		(3,334)	(5,546)
Administrative expenses		(112)	(150)
Benefit obligation at end of period		94,742	83,141	73,380
Change in Plan Assets:
Fair value of plan assets at beginning of period		93,749	86,180
Actual return on plan assets		11,626	13,265
Employer contributions		0	0
Benefits paid		(3,334)	(5,546)
Administrative expenses		(112)	(150)
Fair value of plan assets at end of period		101,929	93,749	86,180
Funded (unfunded) status at end of period		7,187	10,608
Non-Qualified Retirement Plans [Member]
Change in Benefit Obligation:
Benefit obligation at beginning of period		16,438	14,626
Service cost	[1]	170	126	108
Interest cost	[2]	465	563	475
Actuarial (gain) loss		1,803	2,028
Benefits paid		(903)	(905)
Administrative expenses		0	0
Benefit obligation at end of period		17,973	16,438	14,626
Change in Plan Assets:
Fair value of plan assets at beginning of period		0	0
Actual return on plan assets		0	0
Employer contributions		903	905
Benefits paid		(903)	(905)
Administrative expenses		0	0
Fair value of plan assets at end of period		0	0	$ 0
Funded (unfunded) status at end of period		$ (17,973)	$ (16,438)

[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.