Capital Stock (Narrative) (Details) - Jun. 30, 2015 - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Total	Total
Cash dividends declared, per share of common stock	$ 0.345	$ 0.69
Stock Repurchased and Retired During Period, Shares		3.5
Repurchase and retirement of 1.3 million shares of common stock		$ 324
2015 $2.0 Billion Repurchase Agreement
Stock Repurchase Program, Authorized Amount	$ 2,000	2,000
Repurchase and retirement of 1.3 million shares of common stock	48
Stock Repurchase Program, Remaining Authorized Repurchase Amount	2,000	2,000
2012 $405.0 Million Repurchase Agreement
Stock Repurchase Program, Authorized Amount	$ 405	405
Stock Repurchased and Retired During Period, Shares	1.6
Repurchase and retirement of 1.3 million shares of common stock	$ 146
Stock Repurchase Program, Remaining Authorized Repurchase Amount	259	259
2011 $500.0 Million Repurchase Agreement
Stock Repurchase Program, Authorized Amount	$ 500	$ 500
Stock Repurchased and Retired During Period, Shares	0.5