Employee and Retiree Benefit Plans (One Percent Change in Assumed Health Care Cost Trend Rates) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)
Employee and Retiree Benefit Plans [Abstract]
1% Increase, Effect on total service and interest cost components of net periodic postretirement benefit expense for the year ended December 31, 2015	$ 1,451
1% Increase, Effect on the health care component of the accumulated postretirement benefit obligation at December 31, 2015	17,284
1% Decrease, Effect on total service and interest cost components of net periodic postretirement benefit expense for the year ended December 31, 2015	(1,094)
1% Decrease, Effect on the health care component of the accumulated postretirement benefit obligation at December 31, 2015	$ (13,806)