Derivative Financial Instruments Fair Value of Derivative Instrument (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Accrued expenses [Member]
Derivatives, Fair Value [Line Items]
Financial liabilities carried at fair value	$ 1,747	$ 846
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Other long-term liabilities [Member]
Derivatives, Fair Value [Line Items]
Financial liabilities carried at fair value	13,411	11,655
British pound forward contracts [Member] | Designated as Hedging Instrument [Member] | Other assets, net [Member]
Derivatives, Fair Value [Line Items]
Financial assets carried at fair value	26,359	1,530
British pound forward contracts [Member] | Designated as Hedging Instrument [Member] | Other long-term liabilities [Member]
Derivatives, Fair Value [Line Items]
Financial liabilities carried at fair value	17	0
Currency Swap [Member] | Not Designated as Hedging Instrument [Member] | Other assets, net [Member]
Derivatives, Fair Value [Line Items]
Financial assets carried at fair value	506	0
Currency Swap [Member] | Not Designated as Hedging Instrument [Member] | Prepaid expenses and other [Member]
Derivatives, Fair Value [Line Items]
Financial assets carried at fair value	174	0
Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Financial liabilities carried at fair value	15,175	12,501
Fair Value, Inputs, Level 2 [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Financial assets carried at fair value	680	0
Fair Value, Inputs, Level 2 [Member] | British pound forward contracts [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Financial assets carried at fair value	$ 26,359	$ 1,530