Components of Net Periodic Pension Cost (Schedule of Changes as a result of ASU 2017-07) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other components of net periodic pension expense	$ 7	$ 62	$ 21	$ 189
Salaries and employee benefits	$ 10,174	8,810	$ 29,575	25,521
Accounting Standards Update 2017-07 [Member] | Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other components of net periodic pension expense
Salaries and employee benefits		$ 8,872		$ 25,710