Business Segments and Geographic Information (Pre-Tax Income Reconciliation of Segments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pre-Tax Income Reconciliation of Segments
Total operating income from segments	$ 449,180	$ 438,628	$ 414,293
Unallocated amounts:
General and administrative expense	(184,515)	(190,343)	(148,709)
Net interest expense	(115,348)	(96,348)	(100,222)
Loss on extinguishment of debt	0	0	(15,885)
Income Before Income Taxes and Equity in Earnings of Affiliates	149,317	151,937	149,477
Operating Segments
Pre-Tax Income Reconciliation of Segments
Total operating income from segments	$ 449,180	$ 438,628	$ 414,293