Fair Value Disclosures - Assets And Liabilities Measured At Fair Value On Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets:
Assets measured at fair value on a recurring basis	$ 94,746	$ 93,590
Fair Value, Inputs, Level 1 | Deferred compensation plan assets
Assets:
Assets measured at fair value on a recurring basis	17,743	29,108
Fair Value, Inputs, Level 2
Assets:
Assets measured at fair value on a recurring basis	77,003	64,482
Liabilities:
Liabilities measured at fair value on a recurring basis	872,621	929,065
Fair Value, Inputs, Level 2 | Foreign currency forward contracts
Assets:
Assets measured at fair value on a recurring basis	320	2,053
Liabilities:
Liabilities measured at fair value on a recurring basis	721	1,605
Fair Value, Inputs, Level 2 | Interest rate swap contracts
Assets:
Assets measured at fair value on a recurring basis	22,380	3,412
Fair Value, Inputs, Level 2 | Deferred compensation plan assets
Assets:
Assets measured at fair value on a recurring basis	54,303	59,017
Fair Value, Inputs, Level 2 | Deferred compensation plan liabilities
Liabilities:
Liabilities measured at fair value on a recurring basis	76,828	89,900
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	$ 795,072	$ 837,560