Derivative Financial Instruments (Schedule of Fair Values of the Company's Derivative Instruments and the Line Items on the Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Gross Amounts of recognized assets	$ 1,028	$ 1,799
Gross Amounts of recognized liabilities	209	8,192
Prepaid expenses and other current assets | Derivative assets not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Gross Amounts of recognized assets	995	1,314
Prepaid expenses and other current assets | Derivative assets designated as hedging instruments
Derivatives, Fair Value [Line Items]
Gross Amounts of recognized assets	33	485
Other accrued liabilities | Derivative assets not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Gross Amounts of recognized liabilities	189	7,128
Other accrued liabilities | Derivative assets designated as hedging instruments
Derivatives, Fair Value [Line Items]
Gross Amounts of recognized liabilities	$ 20	$ 1,064