Pension and Other Postretirement Benefit Plans (Plan assets) (Details) - Swiss Pension Plan	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Expected future long-term rate of return on plan assets, percent	3.00%	2.50%
Swiss Bonds
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, percentage	14.00%
Historical asset rates of return (percentage)	(0.69%)	(1.11%)
Non Swiss Hedged Bonds
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, percentage	10.00%
Swiss Equities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, percentage	10.00%
Historical asset rates of return (percentage)	3.50%	3.00%
Global Equities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, percentage	15.00%
Hedged Foreign Bonds
Defined Benefit Plan Disclosure [Line Items]
Historical asset rates of return (percentage)	(0.43%)	(1.20%)
Real Estate
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, percentage	40.00%
Historical asset rates of return (percentage)	2.54%	2.10%
Unhedged Global Equities
Defined Benefit Plan Disclosure [Line Items]
Historical asset rates of return (percentage)	5.38%	4.80%
Emerging Market Equities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, percentage	5.00%
Historical asset rates of return (percentage)	5.79%	5.00%
Alternative Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, percentage	4.00%
Historical asset rates of return (percentage)	2.52%	1.80%
Cash held in Swiss Franc, Euro and USD
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation, percentage	2.00%
Historical asset rates of return (percentage)	0.27%	(0.20%)