Shareholders' Equity (Schedule of Share Repurchase Plan Authorization) (Details) (USD $) In Millions	1 Months Ended			6 Months Ended
	Apr. 30, 2011	Oct. 31, 2008	Feb. 29, 2008	Jun. 30, 2011
Shareholders' Equity [Abstract]
Share Repurchase Plan, Authorized Repurchase Amount	$ 129	$ 100	$ 400	$ 629