Stock-Based Compensation (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2007 Y
Restricted Stock and Restricted Stock Units
Unit and Shares Activity:
Number of Awards - Nonvested - Beginning balance	4,812,657	4,379,480	2,957,538
Number of Awards - Granted	889,448	902,549	1,150,819
Number of Awards - Granted - Other	351,624	527,823	522,581
Number of Awards - Vested	(1,077,816)	(948,233)	(157,104)
Number of Awards - Forfeited	(116,941)	(48,962)	(94,354)
Number of Awards - Nonvested - Ending balance	4,858,972	4,812,657	4,379,480
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	$ 68.75	$ 68.85	$ 77.41
Weighted Average Grant Date Fair Value - Annual	$ 89.46	$ 78.81	$ 53.89
Weighted Average Grant Date Fair Value - Other	$ 87.07	$ 70.09	$ 54.82
Weighted Average Grant Date Fair Value - Vested	$ 72.21	$ 79.12	$ 73.26
Weighted Average Grant Date Fair Value - Forfeited	$ 72.01	$ 76.22	$ 69.57
Weighted Average Grant Date Fair Value - Nonvested - Ending balance	$ 73.02	$ 68.75	$ 68.85
Employee Service Share-based Compensation, Equity Awards Other than Options, Unrecognized Compensation Costs on Nonvested Awards	$ 85,000,000
Weighted average life for remaining vesting period of restricted stock and restricted stock units (in years)	2.1
Vesting period, generally (in years)	3
Vesting period of "buyout" grant of restricted stock units (in years)				5
Fair value of restricted stock and restricted stock units that vested	102,000,000	75,000,000	10,000,000
Tax benefit realized from vesting of restricted stock and restricted stock units	36,000,000	20,000,000
Performance Shares
Unit and Shares Activity:
Number of Awards - Nonvested - Beginning balance	760,645
Number of Awards - Granted	415,024	370,575
Number of Awards - Vested	(206,410)
Performance change	(39,323)	396,390
Number of Awards - Forfeited	(51,064)	(6,320)
Performance criteria, number of key factors	3
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	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
Number of Awards - Nonvested - Ending balance	878,872	760,645
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	$ 73.99
Weighted Average Grant Date Fair Value - Other	$ 84.58	$ 74.46
Weighted Average Grant Date Fair Value - Vested	$ 72.77
Weighted Average Grant Date Fair Value - Performance change	$ 82.10	$ 73.55
Weighted Average Grant Date Fair Value - Forfeited	$ 80.20	$ 73.92
Weighted Average Grant Date Fair Value - Nonvested - Ending balance	$ 78.55	$ 73.99
Compensation expense yet to be recognized for restricted stock and restricted stock units	11,000,000
Weighted average life for remaining vesting period of restricted stock and restricted stock units (in years)	0.8
Fair value of restricted stock and restricted stock units that vested	18,000,000
Tax benefit realized from vesting of restricted stock and restricted stock units	$ 5,000,000