Stockholders' Equity (Schedule of Treasury Stock) (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended					6 Months Ended			74 Months Ended		6 Months Ended	77 Months Ended
	Feb. 28, 2014	Oct. 31, 2012	Apr. 30, 2011	Oct. 31, 2008	Feb. 29, 2008	Jun. 30, 2014	Jun. 30, 2013		Mar. 31, 2014		Jun. 30, 2013 Restricted Stock [Member]	Jun. 30, 2014 Restricted Stock [Member]
Class of Stock [Line Items]
Share repurchase plan, authorized repurchase amount	$ 172	$ 264	$ 129	$ 100	$ 400				$ 1,065
Shares repurchased						1,870,297	137,692	[1]	18,199,004	[2]
Average purchase price per share						$ 55.13	$ 46.24		$ 42.21
Amount spent on repurchased shares						$ 103	$ 6		$ 768
Shares withheld, tax withholding											6,021	11,844

[1] Excludes 6,021 shares withheld from an executive officer to cover statutory minimum withholding requirements for personal income taxes related to the vesting of restricted stock. Restricted stock awards are considered outstanding at the time of issuance and therefore, the shares withheld are treated as treasury shares.

[2] Excludes 11,844 shares withheld from an executive officer to cover statutory minimum withholding requirements for personal income taxes related to the vesting of restricted stock. Restricted stock awards are considered outstanding at the time of issuance and therefore, the shares withheld are treated as treasury shares.