Stockholders' Equity (Share Repurchase Program) (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended		1 Months Ended		6 Months Ended	1 Months Ended	132 Months Ended	1 Months Ended	29 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Feb. 28, 2013 December 2012 Buyback Plan [Member]	Dec. 31, 2012 December 2012 Buyback Plan [Member]	Jun. 30, 2013 December 2012 Buyback Plan [Member]	Jun. 30, 2001 June 2001 Buyback Plan [Member]	Jun. 30, 2012 June 2001 Buyback Plan [Member]	Apr. 30, 2011 April 2011 Buyback Plan [Member]	Sep. 30, 2013 April 2011 Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount				$ 1,000		$ 2,000		$ 2,000
Payment for the repurchase of common stock	$ 1,000	$ 400	$ 1,000						$ 284
Stock Repurchased and Retired During Period, Shares		7.8			20.4		42.0		5.5