Significant Accounting Policies Fair Value Measurements (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange contracts, net			$ 48,545
Debt and Capital Lease Obligations		$ 2,101,282	1,962,570
Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value		2,164,529	2,013,684
Reported Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt and Capital Lease Obligations		2,101,282	1,962,570
Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange contracts, net			51,673
Total assets at fair value		50,306
Non-qualified deferred compensation liabilities			(48,545)
Financial and Nonfinancial Liabilities, Fair Value Disclosure		(53,073)	(51,210)
Fair value, measurements, recurring | Supplemental Employee Retirement Plans, Defined Benefit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-qualified deferred compensation assets		48,330	48,545
Non-qualified deferred compensation liabilities		(48,330)
Fair value, measurements, recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value		48,330
Financial and Nonfinancial Liabilities, Fair Value Disclosure		(48,330)	(48,545)
Fair value, measurements, recurring | Level 1 | Supplemental Employee Retirement Plans, Defined Benefit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-qualified deferred compensation assets		48,330	48,545
Non-qualified deferred compensation liabilities		(48,330)	(48,545)
Fair value, measurements, recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value		1,976	3,128
Financial and Nonfinancial Liabilities, Fair Value Disclosure		(4,743)	(2,665)
Foreign Exchange Contract | Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset			3,128
Foreign exchange contracts, net		1,976
Foreign Exchange Contract | Fair value, measurements, recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange contracts, net			3,128
Interest rate swap | Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange contracts, net		(4,743)	(2,665)
Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value— Assets		1,976	3,128
Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets | Foreign Exchange Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value— Assets	[1]	1,976	3,128
Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value— Assets	[1]	$ (4,743)	$ (2,665)

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