Segment Information Revenues By Region (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers [Line Items]
Total revenues	$ 495,713	$ 506,859	$ 513,024	$ 497,590	$ 496,448	$ 469,528	$ 470,811	$ 446,746	$ 2,013,186	$ 1,883,533	$ 1,947,616
United States and Canada [Member]
Revenues from External Customers [Line Items]
Total revenues									1,126,787	997,293	875,796
EMEA [Member]
Revenues from External Customers [Line Items]
Total revenues									698,106	701,301	849,841
Other Countries [Member]
Revenues from External Customers [Line Items]
Total revenues									$ 188,293	$ 184,939	$ 221,979