Earnings Per Share (Schedule of Earnings Per Share, Basic and Diluted) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Income from continuing operations, net of tax									$ 306	$ 789	$ 284
Weighted Average Number of Shares Outstanding, Basic (in shares)									687	720	743
Income (Loss) from Continuing Operations, Per Basic Share	$ (0.13)	$ 0.27	$ 0.10	$ 0.20	$ 0.29	$ 0.68	$ 0.20	$ (0.07)	$ 0.45	$ 1.10	$ 0.38
Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants (in shares)									0	1	1
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements (in shares)									2	3	4
Income (Loss) From Continuing Operations Diluted									$ 306	$ 789	$ 284
Weighted Average Number of Shares Outstanding, Diluted (in shares)									689	724	748
Income (Loss) from Continuing Operations, Per Diluted Share	$ (0.13)	$ 0.26	$ 0.10	$ 0.20	$ 0.29	$ 0.67	$ 0.20	$ (0.07)	$ 0.44	$ 1.09	$ 0.38
Employee Stock Option [Member]
Class of Stock [Line Items]
Income (Loss) from Continuing Operations, Per Diluted Share									0.00	0.00	0.00
Restricted Stock Units (RSUs) [Member]
Class of Stock [Line Items]
Income (Loss) from Continuing Operations, Per Diluted Share									$ (0.01)	$ (0.01)	$ 0.00
Restricted Stock Units (RSUs) [Member]
Class of Stock [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units									$ 0	$ 0	$ 0
Equity Option [Member]
Class of Stock [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units									$ 0	$ 0	$ 0