Employee Benefits (Schedule of Net Funded (Unfunded) Status) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Qualified Pension Plan [Member]
Change in Benefit Obligation:
Benefit obligation at beginning of period		$ 80,723	$ 72,951
Service cost	[1]	2,244	2,149	$ 2,148
Interest cost	[2]	2,715	2,673	2,576
Actuarial (gain) loss		(7,830)	7,017
Benefits paid		(4,344)	(3,936)
Administrative expenses		(128)	(131)
Benefit obligation at end of period		73,380	80,723	72,951
Change in Plan Assets:
Fair value of plan assets at beginning of period		87,364	75,787
Actual return on plan assets		288	12,644
Employer contributions		3,000	3,000
Benefits paid		(4,344)	(3,936)
Administrative expenses		(128)	(131)
Fair value of plan assets at end of period		86,180	87,364	75,787
Funded (unfunded) status at end of period		12,800	6,641
Non-Qualified Retirement Plans [Member]
Change in Benefit Obligation:
Benefit obligation at beginning of period		15,203	13,154
Service cost	[1]	108	129	122
Interest cost	[2]	475	428	432
Actuarial (gain) loss		(252)	2,275
Benefits paid		(908)	(783)
Administrative expenses		0	0
Benefit obligation at end of period		14,626	15,203	13,154
Change in Plan Assets:
Fair value of plan assets at beginning of period		0	0
Actual return on plan assets		0	0
Employer contributions		908	783
Benefits paid		(908)	(783)
Administrative expenses		0	0
Fair value of plan assets at end of period		0	0	$ 0
Funded (unfunded) status at end of period		$ (14,626)	$ (15,203)

[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.