Segment and Geographic Information, Segment and Geographic Info (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from external customers	$ 1,383,210	$ 1,375,964	$ 1,447,821
Long-lived assets	950,799	974,827	1,034,385
Reportable Geographical Components [Member] | North America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from external customers	745,660	744,481	750,345
Long-lived assets	548,674	541,654	566,236
Reportable Geographical Components [Member] | Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from external customers	342,818	349,100	389,588
Long-lived assets	361,029	397,244	423,972
Reportable Geographical Components [Member] | Asia Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from external customers	196,884	177,559	193,163
Long-lived assets	30,006	26,589	29,948
Reportable Geographical Components [Member] | Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from external customers	97,848	104,824	114,725
Long-lived assets	11,090	9,340	14,229
Reportable Geographical Components [Member] | United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from external customers	595,000	592,900	573,600
Long-lived assets	$ 495,300	$ 486,100	$ 479,400