Consolidated Statements of Financial Position (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Accumulated depreciation	$ 4,146	$ 3,933
Long-term debt, current portion	$ 5	$ 5
Preferred Stock, par value	$ 1	$ 1
Preferred Stock, shares authorized	10,000,000	10,000,000
Preferred Stock, shares issued	0	0
Preferred Stock, shares outstanding	0	0
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares issued	239,209,812	253,889,622
Common stock, shares outstanding	239,209,812	253,889,622