Employee Benefit Plans (Schedule of Changes in Benefit Obligation and Plan Assets) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amounts recognized in accumulated other comprehensive loss
Total		$ 3,988	$ 2,130
Supplemental Executive Retirement Plan [Member]
Benefit obligations:
Beginning of year		11,523	11,052
Service cost		335	308	$ 307
Interest cost		452	432	424
Actuarial loss		1,955	219
Benefits paid		(475)	(488)
End of year		13,790	11,523	11,052
Fair value of plan assets:
Beginning of year		0	0
Employer contributions		475	488
Benefits paid		(475)	(488)
End of year		0	0	0
Unfunded status at end of year(1)	[1]	13,790	11,523
Amounts recognized in accumulated other comprehensive loss
Net actuarial loss		3,504	1,791
Total		3,504	1,791
Other Postretirement Benefit Plan [Member]
Benefit obligations:
Beginning of year		3,635	3,447
Service cost		53	59	62
Interest cost		144	151	117
Actuarial loss		110	143
Benefits paid		(151)	(165)
End of year		3,791	3,635	3,447
Fair value of plan assets:
Beginning of year		0	0
Employer contributions		151	165
Benefits paid		(151)	(165)
End of year		0	0	$ 0
Unfunded status at end of year(1)	[1]	3,791	3,635
Amounts recognized in accumulated other comprehensive loss
Net actuarial loss		654	495
Prior service credit		(170)	(156)
Total		$ 484	$ 339

[1] 1)Presented within other liabilities on the consolidated statements of condition.