Employee Benefit Plans (Components of Postretirement Benefit Expense) (Details) (Postretirement Medical and Life Benefit Plan, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Postretirement Medical and Life Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 41	$ 40	$ 35
Interest Cost	28	23	24
Amortization of Unrecognized Net (Gain) Loss	0	4	0
Net Periodic Benefit Cost	69	67	59
Net Gain (Loss) During Period Recognized in Other Comprehensive Income (Loss)	46	(37)	42
Total Recognized in Net Periodic Benefit Cost and Other Comprehensive Income (Loss)	$ 115	$ 30	$ 101