Employee and Retiree Benefit Plans (Effects of Fair Value Measurements Using Significant Unobservable Inputs on Changes in Level 3 Plan Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Insurance [Abstract]
Beginning Balance	$ 33,929	$ 33,952
Relating to assets held at the reporting date	185	(23)
Relating to assets sold during the period
Purchases, sales and settlements
Ending Balance	$ 34,114	$ 33,929