Stockholders' Equity (Narrative) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended	6 Months Ended	1 Months Ended			132 Months Ended	1 Months Ended	23 Months Ended
	Feb. 28, 2013	Mar. 31, 2012	Jun. 30, 2012	Feb. 28, 2013 December 2012 Buyback Plan [Member]	Dec. 31, 2012 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]	Mar. 31, 2013 April 2011 Buyback Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount					$ 1,000	$ 2,000		$ 2,000
DPC Sale Proceeds Used for Share Repurchase				1,000
Prepayment for the repurchase of common stock		400		1,000
Stock Repurchased and Retired During Period, Shares			7.8	16.9			42.0		5.5
PercentageofShareRepurchaseAgreementCompleted	80.00%
Stock Repurchased and Retired During Period, Value									$ 284