Retirement Benefits Projected Benefit Obligation Assumptions (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.12%	4.71%	4.23%
Rate of compensation increase	3.55%	3.59%	3.15%
Discount rate	4.71%	4.23%	5.04%
Expected return on plan assets	6.04%	6.36%	6.06%
Rate of compensation increase	3.59%	3.15%	3.18%
Other Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.10%	4.60%	4.10%
Rate of compensation increase	3.93%	3.92%	3.60%
Discount rate	4.60%	4.10%	4.60%
Rate of compensation increase	3.92%	3.60%	3.58%