Stock-Based Compensation (Schedule of Unrecognized Compensation Costs and Amortization Periods) (Details) $ in Millions	12 Months Ended
Dec. 31, 2015 USD ($)
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Nonvested stock options	$ 9
Weighted-Average Service Years	1 year 3 months 18 days
Restricted share units
Share-based Compensation Arrangement by Share-based Payment Award
Total remaining unrecognized compensation costs, nonvested awards other than options	$ 5
Weighted-Average Service Years	1 year 10 months 24 days
Performance-based restricted share units
Share-based Compensation Arrangement by Share-based Payment Award
Total remaining unrecognized compensation costs, nonvested awards other than options	$ 52
Weighted-Average Service Years	1 year 10 months 24 days

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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