Financial Instruments, Derivatives and Hedging Activities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Foreign Currency Movement Effect
Net currency exchange gains included in determining Income from Operations	$ 4,700,000	$ 1,400,000	$ 5,400,000
Derivative Contracts Designated as Hedging Instruments | Instruments in a Cash Flow Hedging Relationship | Interest Rate Swap Agreements
Interest Rate Risk
Notional amount	$ 560,000,000
Interest rate derivatives, fixed rate, lower range	0.45%
Interest rate derivatives, fixed rate, higher range	0.82%
Amounts excluded from the measure of effectiveness	$ 0	0
Commodity Risk
Amounts excluded from the measure of effectiveness	0	0
Foreign Currency Risk
Notional amount	560,000,000
Amounts excluded from the measure of effectiveness	0	0
Derivatives Not Designated as Hedges
Notional amount	560,000,000
Derivative Contracts Designated as Hedging Instruments | Instruments in a Cash Flow Hedging Relationship | Forward Starting Interest Rate Swaps
Interest Rate Risk
Notional amount	$ 450,000,000
Interest rate derivatives, fixed rate, lower range	0.73%
Interest rate derivatives, fixed rate, higher range	1.40%
Foreign Currency Risk
Notional amount	$ 450,000,000
Derivatives Not Designated as Hedges
Notional amount	450,000,000
Derivative Contracts Designated as Hedging Instruments | Instruments in a Cash Flow Hedging Relationship | Commodity Contracts
Interest Rate Risk
Amounts excluded from the measure of effectiveness	0	0
Commodity Risk
Amounts excluded from the measure of effectiveness	0	0
Foreign Currency Risk
Amounts excluded from the measure of effectiveness	0	0
Derivative Contracts Designated as Hedging Instruments | Instruments in a Cash Flow Hedging Relationship | Forward Exchange Contract
Interest Rate Risk
Notional amount	65,200,000
Amounts excluded from the measure of effectiveness	0	0
Commodity Risk
Amounts excluded from the measure of effectiveness	0	0
Foreign Currency Risk
Notional amount	65,200,000
Amounts reclassified into earnings connected to forecasted transactions no longer considered probable	0	0
Amount of ineffectiveness related to changes in the fair value of derivatives	0	0
Amounts excluded from the measure of effectiveness	0	0
Derivatives Not Designated as Hedges
Notional amount	65,200,000
Derivative Contracts Not Designated as Hedging Instruments | Forward Exchange Contract
Interest Rate Risk
Notional amount	45,500,000	34,500,000
Foreign Currency Risk
Notional amount	45,500,000	34,500,000
Derivatives Not Designated as Hedges
Notional amount	$ 45,500,000	$ 34,500,000