Business Segments and Geographic Information (Details 1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pre-Tax Income Reconciliation of Segments
Total operating income from segments	$ 63,031	$ 63,318	$ 168,977	$ 172,777
Unallocated Amount:
General and Administrative Expenses	(33,742)	(28,287)	(97,764)	(84,937)
Income before income taxes and equity in earnings of affiliates	38,709	42,958	98,300	112,719
Operating Segments
Pre-Tax Income Reconciliation of Segments
Total operating income from segments	96,773	91,605	266,741	257,714
Segment Reconciling Items
Unallocated Amount:
General and Administrative Expenses	(33,742)	(28,287)	(97,764)	(84,937)
Net Interest Expense	$ (24,322)	$ (20,360)	$ (70,677)	$ (60,058)