Derivative Financial Instruments Fair Value of the Company's Derivative Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Interest rate swap agreements [Member] | Designated as Hedging Instrument [Member] | Accrued expenses [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 1,952	$ 1,747
Interest rate swap agreements [Member] | Designated as Hedging Instrument [Member] | Other long-term liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	13,168	13,411
British pound forward contracts [Member] | Designated as Hedging Instrument [Member] | Other assets, net [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	24,570	26,359
British pound forward contracts [Member] | Designated as Hedging Instrument [Member] | Other long-term liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	51	17
Currency Swap [Member] | Not Designated as Hedging Instrument [Member] | Other assets, net [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	506
Currency Swap [Member] | Not Designated as Hedging Instrument [Member] | Accrued expenses [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	3,888	0
Currency Swap [Member] | Not Designated as Hedging Instrument [Member] | Other long-term liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	6,305	0
Currency Swap [Member] | Not Designated as Hedging Instrument [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	174
Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	24,570	26,359
Derivative Liability, Fair Value, Gross Liability	15,171	15,175
Fair Value, Inputs, Level 2 [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	680
Derivative Liability, Fair Value, Gross Liability	$ 10,193	$ 0