Employee Retirement Plans (Schedule of Total Expense for All Retirement Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Total retirement plan expense	$ 2,887	$ 2,934	$ 2,816