Annual report pursuant to Section 13 and 15(d)

Financial Instruments and Risk Management (Narrative) (Details)

v2.4.1.9
Financial Instruments and Risk Management (Narrative) (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Derivatives [Line Items]  
Deferred net gains on derivatives accumulated in other comprehensive income expected to be reclassified to net income in next twelve months $ 10,918,000us-gaap_ForeignCurrencyCashFlowHedgeGainLossToBeReclassifiedDuringNext12Months
Maximum [Member]  
Derivatives [Line Items]  
Remaining maturity of derivative contracts 1 year
Aggregate unrealized gain of derivative contracts with single counterparty $ 4,000,000us-gaap_FairValueConcentrationOfRiskForeignCurrencyContractAsset
/ us-gaap_RangeAxis
= us-gaap_MaximumMember