Business Segments and Geographic Information - Income Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Pre-Tax Income Reconciliation of Segments
Total operating income from segments	$ 62,902	$ 72,451	$ 181,827	$ 197,575
Unallocated Amount:
General and Administrative Expenses	(49,074)	(37,483)	(143,866)	(108,448)
Loss on extinguishment of debt	0	0	0	(15,885)
Income before income taxes and equity in earnings of affiliates	38,831	46,951	111,096	106,213
Operating Segments
Pre-Tax Income Reconciliation of Segments
Total operating income from segments	111,976	109,934	325,693	306,023
Segment Reconciling Items
Unallocated Amount:
General and Administrative Expenses	(49,074)	(37,483)	(143,866)	(108,448)
Interest Income (Expense), Nonoperating, Net	(24,071)	(25,500)	(70,731)	(75,477)
Loss on extinguishment of debt	$ 0	$ 0	$ 0	$ (15,885)