Stock-Based Compensation (Details 2) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock option activity [Rollforward]
Exercised (in shares)	(1,892,962)	(2,530,462)
Stock Option [Member]
Assumptions used to value stock option awards [Abstract]
Expected term (in years)	5 years 8 months	5 years 8 months	5 years 8 months
Expected volatility (in hundredths)	36.40%	37.00%	36.20%
Risk-free rate (in hundredths)	1.10%	0.90%	2.20%
Expected dividend yield (in hundredths)	1.20%	1.20%	1.10%
Weighted-average grant-date fair value of options granted (in dollars per share)	$ 17.08	$ 15.99	$ 15.09
Stock option activity [Rollforward]
Outstanding, beginning balance (in shares)	12,411,572
Granted (in shares)	2,492,855
Exercised (in shares)	(1,892,962)
Forfeited (in shares)	(333,608)
Outstanding, ending balance (in shares)	12,677,857	12,411,572
Exercisable (in shares)	8,383,018
Stock option activity, additional disclosures [Abstract]
Weighted average exercise price per share outstanding, beginning balance (in dollars per share)	$ 35.14
Weighted average exercise price per share granted (in dollars per share)	$ 54.64
Weighted average exercise price per share exercised (in dollars per share)	$ 27.05
Weighted average exercise price per share forfeited (in dollars per share)	$ 51.99
Weighted average exercise price per share outstanding, ending balance (in dollars per share)	$ 39.82	$ 35.14
Weighted average exercise price per exercisable share (in dollars per share)	$ 33.53
Weighted average remaining contractual term of shares outstanding (in years)	6 years 2 months 12 days
Aggregate intrinsic value of shares outstanding	$ 359
Weighted average remaining contractual term, exercisable shares (in years)	5 years
Aggregate intrinsic value, exercisable shares	290
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Minimum term to maturity on US Treasuries used to determine the risk free rate assumption in valuing stock options	5 years
Maximum term to maturity on US Treasuries used to determine the risk free rate assumption in valuing stock options	7 years
The period ended, prior to the date of grant, over which an average of daily stock prices is computed in determining the dividend yield	3 years
Duration of Dividends	1 year
Total intrinsic value of options exercised	64	72	40
Unrecognized compensation cost related to nonvested awards	39
The weighted-average period over which unrecognized compensation cost is to be recognized (in years)	1 year 3 months 18 days
Restricted Stock [Member]
Assumptions used to value stock option awards [Abstract]
Expected volatility (in hundredths)	30.00%
Risk-free rate (in hundredths)	0.40%
Restricted stock awards, shares subject to service conditions, additional disclosures [Abstract]
Weighted average award date fair value, shares awarded (in dollars per share)	$ 38.07	$ 50.75	$ 45.16
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Unrecognized compensation cost related to nonvested awards	47
The weighted-average period over which unrecognized compensation cost is to be recognized (in years)	1 year 5 months
Weighted average award date fair value, shares awarded (in dollars per share)	$ 38.07	$ 50.75	$ 45.16
Total fair value of vested restricted stock	$ 43	$ 47	$ 57
Stock Option And Restricted Stock Plan 1992 [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Number of shares of common stock reserved for issuance (in shares)	35,652,195
Shares of common stock available for future grants and awards (in shares)	18,549,928
Expiration period (in years)	10 years
Stock option vesting period	3 years
Percentage of restricted stock awards that time-vest one year from date of grant (in hundredths)	20.00%
Additional percentage of restricted stock awards that time-vest two years from date of grant (in hundredths)	30.00%
Remaining percentage of restricted stock awards that time-vest three years from date of grant (in hundredths)	50.00%
Stock Plan for Non-Employee Directors 2005 [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Maximum number of shares of common stock authorized for issuance After April 26, 2011 (in shares)	1,600,000
Number of shares of common stock reserved for issuance (in shares)	1,376,644
Shares of common stock available for future grants and awards (in shares)	893,820
Expiration period (in years)	10 years
Stock option vesting period	1 year
The maximum number of stock options authorized for annual and discretionary grants per non-employee director (in shares)	22,400
The number of stock options authorized for annual grants per non-employee director (in shares)	5,600
The maximum number of shares of restricted stock authorized for annual and discretionary grants per non-employee director (in shares)	9,600
The number of shares of restricted stock authorized for annual grants per non-employee director (in shares)	2,400
Nonqualified Stock Option Plan for Non-Employee Directors 1988 [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Expiration period (in years)	10 years
Stock option vesting period	1 year
The number of stock options authorized for annual grants per non-employee director (in shares)	10,000
The number of stock options granted during the first calendar year of service (in shares)	20,000
Subject to Time Vesting [Member] | Restricted Stock [Member]
Restricted Stock Awards Activity [Roll Forward]
Outstanding, beginning balance (in shares)	1,866,462
Awarded (in shares)	485,587
Vested (in shares)	(781,838)
Forfeited (in shares)	(82,342)
Outstanding, ending balance (in shares)	1,487,869
Restricted stock awards, shares subject to service conditions, additional disclosures [Abstract]
Weighted average award date fair value, beginning of period (in dollars per share)	$ 46.40
Weighted average award date fair value, shares awarded (in dollars per share)	$ 54.81
Weighted average award date fair value, shares vested (in dollars per share)	$ 43.04
Weighted average award date fair value, shares forfeited (in dollars per share)	$ 50.04
Weighted average award date fair value, end of period (in dollars per share)	$ 50.74
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Weighted average award date fair value, shares awarded (in dollars per share)	$ 54.81
Subject to Market Conditions [Member] | Restricted Stock [Member]
Restricted Stock Awards Activity [Roll Forward]
Outstanding, beginning balance (in shares)	0
Awarded (in shares)	891,504
Vested (in shares)	0
Forfeited (in shares)	(43,478)
Outstanding, ending balance (in shares)	848,026
Restricted stock awards, shares subject to service conditions, additional disclosures [Abstract]
Weighted average award date fair value, beginning of period (in dollars per share)	$ 0.00
Weighted average award date fair value, shares awarded (in dollars per share)	$ 28.96
Weighted average award date fair value, shares vested (in dollars per share)	$ 0.00
Weighted average award date fair value, shares forfeited (in dollars per share)	$ 28.65
Weighted average award date fair value, end of period (in dollars per share)	$ 28.93
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Weighted average award date fair value, shares awarded (in dollars per share)	$ 28.96
Second Vesting Option [Member] | Stock Option And Restricted Stock Plan 1992 [Member]
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Stock option vesting period	2 years
Percentage of restricted stock awards that time-vest one year from date of grant (in hundredths)	40.00%
Additional percentage of restricted stock awards that time-vest two years from date of grant (in hundredths)	60.00%