Segment Information - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenues	$ 1,437,451	$ 1,560,983	$ 2,986,571	$ 3,271,078
Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,606,636	1,710,164	3,360,767	3,593,308
Operating Segments | North America
Segment Reporting Information [Line Items]
Revenues	950,169	933,217	1,853,490	1,956,277
Operating Segments | International
Segment Reporting Information [Line Items]
Revenues	656,467	776,947	1,507,277	1,637,031
Operating Segments | International | Europe
Segment Reporting Information [Line Items]
Revenues	317,143	356,300	656,792	691,085
Operating Segments | International | Latin America
Segment Reporting Information [Line Items]
Revenues	198,760	216,760	411,778	420,826
Operating Segments | International | Global Emerging Markets
Segment Reporting Information [Line Items]
Revenues	140,564	203,887	438,707	525,120
Segment Reconciling Items
Segment Reporting Information [Line Items]
Revenues	$ (169,185)	$ (149,181)	$ (374,196)	$ (322,230)