Employee and Retiree Benefit Plans (One Percent Change in Assumed Health Care Cost Trend Rates) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Employee and Retiree Benefit Plans [Abstract]
Effect on total service and interest cost components of net periodic postretirement benefit expense for the year ended December 31, 2014	$ 1,190
Effect on the health care component of the accumulated postretirement benefit obligation at December 31, 2014	17,879
A 1% decrease effect on total service and interest cost components of net periodic postretirement benefit expense	(942)
A 1% decrease effect on the health care component of the accumulated postretirement benefit obligation	$ (14,456)