Components of Net Periodic Pension Cost (Schedule of Changes as a result of ASU 2017-07) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other components of net periodic pension expense	$ 7	$ 63	$ 14	$ 125
Salaries and employee benefits	$ 9,729	8,569	$ 19,401	16,713
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		$ 8,632		$ 16,838