Segment Information (Revenues By Geographic Location) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 693,227	$ 673,987	$ 1,355,904	$ 1,332,760
Operating Segments [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	693,227	673,987	1,355,904	1,332,760
Operating Segments [Member] | Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	403,072	402,684	794,418	791,370
Operating Segments [Member] | EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	217,313	205,064	419,165	411,995
Operating Segments [Member] | Asia-Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 72,842	$ 66,239	$ 142,321	$ 129,395