Pension and Savings Plans (Details 3) - Pension Plan [Member]	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Weighted-average assumptions used to determine benefit obligations
Discount rate		4.15%	4.55%
Measurement date		Dec. 31, 2016	Dec. 31, 2015
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate		4.55%	4.15%	4.95%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	5.90%	6.00%	6.25%	6.85%