Segment Information (Identifiable Assets By Segment) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Identifiable assets	$ 5,212,249	$ 4,796,402
Long-lived assets	338,996	303,294
United States
Segment Reporting Information [Line Items]
Long-lived assets	258,114	231,812
United Kingdom
Segment Reporting Information [Line Items]
Long-lived assets	29,382	30,633
Other countries
Segment Reporting Information [Line Items]
Long-lived assets	51,500	40,849
Enterprise and Service Provider division
Segment Reporting Information [Line Items]
Identifiable assets	4,662,724	4,246,292
SaaS division
Segment Reporting Information [Line Items]
Identifiable assets	$ 549,525	$ 550,110