Business Segments and Geographic Information (Pre-Tax Income Reconciliation of Segments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pre-Tax Income Reconciliation of Segments
Total operating income from segments	$ 414,293	$ 372,769	$ 349,749
Unallocated amounts:
General and administrative expense	(148,709)	(137,040)	(115,018)
Net interest expense	(100,222)	(94,558)	(82,621)
Loss on extinguishment of debt	(15,885)	0	0
Income Before Income Taxes and Equity in Earnings of Affiliates	149,477	141,171	152,110
Operating Segments
Pre-Tax Income Reconciliation of Segments
Total operating income from segments	$ 414,293	$ 372,769	$ 349,749