Employee and Retiree Benefit Plans (Amounts Included in Accumulated Other Comprehensive Income Expected to be Amortized into Net Periodic Benefit Expense) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ (14,257)
Prior service (cost) credit	(1,019)
Amounts included in accumulated other comprehensive loss expected to be amortized into net periodic benefit cost	(15,276)
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service (cost) credit	74
Amounts included in accumulated other comprehensive loss expected to be amortized into net periodic benefit cost	$ 74