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, 2015	Dec. 31, 2014
Insurance [Abstract]
Beginning Balance	$ 33,952	$ 32,788
Actual return on plan assets:
Relating to assets held at the reporting date	(23)	1,164
Ending Balance	$ 33,929	$ 33,952