Fair Value Disclosures - Assets And Liabilities Measured At Fair Value On Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets:
Assets measured at fair value on a recurring basis	$ 73,411	$ 67,964
Liabilities:
Liabilities measured at fair value on a recurring basis	911,114	858,671
Fair Value, Inputs, Level 1
Assets:
Assets measured at fair value on a recurring basis	10,537	8,956
Fair Value, Inputs, Level 2
Assets:
Assets measured at fair value on a recurring basis	62,874	59,008
Liabilities:
Liabilities measured at fair value on a recurring basis	911,114	858,671
Fair Value, Inputs, Level 2 | Foreign currency forward contracts
Assets:
Assets measured at fair value on a recurring basis	196	1,318
Liabilities:
Liabilities measured at fair value on a recurring basis	550	3,260
Fair Value, Inputs, Level 2 | Interest rate swap contracts
Liabilities:
Liabilities measured at fair value on a recurring basis	30,618	10,681
Fair Value, Inputs, Level 2 | Deferred compensation plan assets
Assets:
Assets measured at fair value on a recurring basis	62,678	57,690
Fair Value, Inputs, Level 2 | Deferred compensation plan liabilities
Liabilities:
Liabilities measured at fair value on a recurring basis	71,210	68,570
Senior Notes
Liabilities:
Long term debt	800,000	800,000
Senior Notes | Fair Value, Inputs, Level 2 | Senior notes
Liabilities:
Liabilities measured at fair value on a recurring basis	$ 808,736	$ 776,160