Benefit Obligations (Valuation Narrative) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	7.30%	7.80%	8.20%
United States Pension Plan of US Entity [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual return on plan assets	6.90%
Expected return on plan assets	7.50%	8.00%	8.50%
United States Postretirement Benefit Plan of US Entity [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next year	9.50%	10.00%	7.00%
Health care cost trend ultimate rate	5.00%	5.00%	5.00%