Stockholders' Equity (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Class of Stock [Line Items]
Value of shares repurchased in prior period but paid for in current period		$ 63,000,000
Common stock par value, per share	$ 1	$ 1
Additional paid-in capital
Cash paid for repurchases of common stock	2,465,000,000	2,420,000,000	1,851,000,000
Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares authorized	1,500,000,000
Preferred stock, shares authorized	50,000,000
Common stock, shares issued and outstanding	323,000,000
Common stock, shares outstanding for Balance Sheet presentation purposes	321,000,000
Additional authorized amount under stock repurchase program	3,500,000,000
Stock repurchase program authorized amount	6,500,000,000
Repurchases of common stock, shares	31,800,000	33,000,000	24,900,000
Repurchases of common stock, value	2,400,000,000	2,500,000,000	1,900,000,000
Number of shares repurchased under the share repurchase program	43,000,000
Remaining authorized repurchase amount	3,300,000,000
Additional paid-in capital	0
Repurchases of common stock under repurchase program	3,200,000,000
Excess of purchase price over par value recorded as a reduction of retained earnings	$ 1,800,000,000	$ 1,900,000,000