Financial Instruments (Financial Instruments Assets (Liabilities) Measured At Fair Value) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 44,886	$ 63,551
Loans payable	(16,494)	(16,360)
Other long-term notes payable	(4,073)	(3,973)
Foreign currency forward contracts, net	2,860	(469)
Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	44,886	63,551
Loans payable	(16,494)	(16,360)
Other long-term notes payable	(6,590)	(7,112)
Foreign currency forward contracts, net	2,860	(469)
Cross Currency Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	10,820
Cross Currency Swaps [Member] | Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	10,820
Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		1,616
Derivative liability	(1,610)	(124)
Interest Rate Swaps [Member] | Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		1,616
Derivative liability	(1,610)	(124)
Revolving Credit Facility, Maturing 2023 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit facility	(573)
Revolving Credit Facility, Maturing 2023 [Member] | Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit facility	(580)
Revolving Credit Facility, Maturing 2022 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit facility		(79,295)
Revolving Credit Facility, Maturing 2022 [Member] | Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit facility		(78,000)
Term Loan Facility, Maturing 2024 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit facility	(807,468)	(646,979)
Unamortized debt issuance costs	5,300	7,500
Term Loan Facility, Maturing 2024 [Member] | Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit facility	(812,665)	(645,242)
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	44,886	63,551
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans payable	(16,494)	(16,360)
Other long-term notes payable	(4,073)	(3,973)
Foreign currency forward contracts, net	2,860	(469)
Level 2 [Member] | Cross Currency Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	10,820
Level 2 [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		1,616
Derivative liability	(1,610)	(124)
Level 2 [Member] | Revolving Credit Facility, Maturing 2023 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit facility	(573)
Level 2 [Member] | Revolving Credit Facility, Maturing 2022 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit facility		(79,295)
Level 2 [Member] | Term Loan Facility, Maturing 2024 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit facility	(807,468)	$ (646,979)
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents
Loans payable
Other long-term notes payable
Foreign currency forward contracts, net
Level 3 [Member] | Cross Currency Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset
Level 3 [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability
Level 3 [Member] | Revolving Credit Facility, Maturing 2023 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit facility
Level 3 [Member] | Term Loan Facility, Maturing 2024 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit facility