Equity Compensation Plans (Narrative) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Percentage of stock options vesting in a period of one year	50.00%
Percentage of stock options vesting in the remaining following years	50.00%
Duration of period in which grants of restricted stock are released after grant date	4 years
Number of shares available for grant	18
Weighted average fair value per option granted	$ 8.90	$ 13.23	$ 15.63
Stock option expense reduced operating earnings	$ 74	$ 88	$ 90
Stock option expense earnings per share	$ 0.14	$ 0.16	$ 0.16
Unrecognized compensation cost related to stock	46
Total intrinsic value of options exercised	154	112	113
Cash received from the exercise of stock options	583	146	198
Stock Options
Awards of stock options vest over number of years	2 years
Period of restriction lapses in which compensation cost is expected to be recognized over a weighted average period (in years)	1 year
Restricted Stock Units
Stock option expense reduced operating earnings	46	26	38
Stock option expense earnings per share	$ 0.09	$ 0.05	$ 0.07
Total fair value of shares vested	63	28	28
Restricted Stock and Restricted Stock Units (RSUs)
Unrecognized compensation cost related to stock	$ 48
Period of restriction lapses in which compensation cost is expected to be recognized over a weighted average period (in years)	2 years 3 months 18 days
Maximum | Stock Options
Stock options expiration period	7 years
Minimum | Stock Options
Stock options expiration period	5 years