Benefit Plans (Assumptions Used) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits [Member]
Weighted average assumptions used in net periodic benefit cost:
Discount rate	3.99%	4.08%	4.50%
Rate of compensation increase	4.04%	4.07%	4.29%
Long-term rate of return on assets	6.95%	6.84%	7.01%
Weighted average assumptions used in benefit obligations:
Discount rate	3.68%	4.22%
Rate of compensation increase	4.04%	4.07%
Other Retirement Benefits [Member]
Weighted average assumptions used in net periodic benefit cost:
Discount rate	4.30%	3.90%	4.55%
Weighted average assumptions used in benefit obligations:
Discount rate	3.90%	4.30%