Defined Contribution Bonus and Profit Sharing Plans Schedule of Bonus and Profit Sharing Plans Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Bonus and Profit Sharing Plans and Awards Expense	$ 40,005	$ 43,377	$ 14,192