Segment Information and Concentrations - Revenue from External Customers by Products and Services (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Information and Concentrations [Abstract]
Product revenue									$ 2,912	$ 2,854	$ 2,592
Professional and installation services revenue									1,259	927	764
Total solution revenue									4,171	3,781	3,356
Support services revenue									1,952	1,949	1,935
Total revenue	$ 1,670	$ 1,508	$ 1,535	$ 1,410	$ 1,642	$ 1,435	$ 1,409	$ 1,244	$ 6,123	$ 5,730	$ 5,291