Business Segments and Geographic Information (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pre-Tax Income Reconciliation of Segments
Total operating income from segments	$ 59,167	$ 52,672
Unallocated Amount:
General and Administrative Expenses	(34,061)	(31,848)
Income before income taxes and equity in earnings of affiliates	34,358	30,099
Operating Segments
Pre-Tax Income Reconciliation of Segments
Total operating income from segments	93,228	84,520
Segment Reconciling Items
Unallocated Amount:
General and Administrative Expenses	(34,061)	(31,848)
Net Interest Expense	$ (24,809)	$ (22,573)