Description of award terms as to the number of shares that could actually be delivered under an award upon satisfaction of a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale, expressed as a percentage of the shares under the award.

No definition available.

Stock-Based Compensation (Details 4) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2012 Y	Jun. 30, 2011	Dec. 31, 2007 Y
Restricted Stock and Restricted Stock Units
Unit and Shares Activity:
Number of Awards - Nonvested - Beginning balance	4,858,972
Number of Awards - Granted - Annual	968,522
Number of Awards - Granted - Other	81,016
Number of Awards - Vested	(2,553,435)
Number of Awards - Forfeited	(49,791)
Number of Awards - Nonvested - Ending balance	3,305,284
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures
Weighted Average Grant Date Fair Value - Nonvested - Beginning balance	$ 73.02
Weighted Average Grant Date Fair Value - Granted - Annual	$ 87.92
Weighted Average Grant Date Fair Value - Granted - Other	$ 84.04
Weighted Average Grant Date Fair Value - Vested	$ 63.54
Weighted Average Grant Date Fair Value - Forfeited	$ 81.49
Weighted Average Grant Date Fair Value - Nonvested - Ending balance	$ 84.85
Weighted average life of remaining vesting period (in years)	2.3
Vesting period, generally (in years)	3
Vesting period of "buyout" grant of restricted stock units (in years)			5
Fair value that vested	$ 162	$ 74
Compensation expense yet to be recognized for stock options	113
Tax benefit realized from vesting	84	23
Performance Shares
Unit and Shares Activity:
Number of Awards - Nonvested - Beginning balance	878,872
Number of Awards - Granted - Annual	441,055
Number of Awards - Performance Change	(32,847)
Number of Awards - Forfeited	(63,535)
Number of Awards - Nonvested - Ending balance	1,223,545
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures
Weighted Average Grant Date Fair Value - Nonvested - Beginning balance	$ 78.55
Weighted Average Grant Date Fair Value - Granted - Annual	$ 81.20
Weighted Average Grant Date Fair Value - Performance Change	$ 81.10
Weighted Average Grant Date Fair Value - Forfeited	$ 80.04
Weighted Average Grant Date Fair Value - Nonvested - Ending balance	$ 79.36
Performance criteria, number of key factors	3
Share-based compensation arrangement by share-based payment award, award performance period (in years)	3
Number of shares to be delivered based on percent of each performance share granted upon satisfaction of performance conditions, minimum	0.00%
Number of shares to be delivered based on percent of each performance share granted upon satisfaction of performance conditions, maximum	200.00%
Vesting period, low end of range (in years)	1
Vesting period, high end of range (in years)	3
Weighted average life of remaining vesting period (in years)	0.8
Fair value that vested		18
Compensation expense yet to be recognized for stock options	28
Tax benefit realized from vesting		$ 5