Capital Stock and Stock-Based Compensation Plans (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Feb. 19, 2015 USD ($)	May 10, 2013 plan
Preference Stock [Abstract]
Shares authorized (in shares)	50,262,150
Stock Repurchases [Abstract]
Repurchased stock | $	$ 1,335	$ 1,551	$ 1,530
Summary of common stock activity [Roll Forward]
Common stock balance, January 1 (in shares)	892,738,518	906,712,145	919,946,575
Common stock acquired (in shares)	(19,271,304)	(22,802,784)	(23,131,081)
Shares issued for stock options (in shares)	8,536,639	7,394,839	7,977,124
Shares issued for restricted stock and other (in shares)	1,105,110	1,434,318	1,919,527
Common stock balance, December 31 (in shares)	883,108,963	892,738,518	906,712,145
Summary Of Treasury Stock Activity [Roll Forward]
Treasury stock balance, January 1 (in shares)	572,967,842	558,994,215	545,759,785
Common stock acquired (in shares)	19,271,304	22,802,784	23,131,081
Shares issued for stock options (in shares)	(8,536,639)	(7,394,839)	(7,977,124)
Shares issued for restricted stock and other (in shares)	(1,105,110)	(1,434,318)	(1,919,527)
Treasury stock balance, December 31 (in shares)	582,597,397	572,967,842	558,994,215
Stock-based compensation [Abstract]
Number of stockholder approved plans, current | plan					1
Number of stockholder approved plans, previous | plan					4
Allocated Share-based Compensation Expense | $	$ 123	$ 125	$ 131
Total income tax benefit | $	$ 40	$ 39	$ 42
Fair Value Assumptions [Abstract]
Weighted-average estimated fair value of stock options granted (in dollars per share) | $ / shares	$ 8.10	$ 7.25	$ 7.60
Expected term (in years)	4 years 6 months	4 years 6 months	4 years 6 months
Expected volatility rate (in hundredths)	16.70%	17.60%	17.10%
Risk-free rate (in hundredths)	1.20%	1.50%	1.60%
Expected dividend yield (in hundredths)	2.10%	2.50%	2.30%
Summary of restricted stock award activity [Roll Forward]
Restricted stock awards - beginning balance (in shares)	3,166,000
Granted (in shares)	933,000
Vested (in shares)	(1,048,000)
Forfeited (in shares)	(106,000)
Restricted stock awards - ending balance (in shares)	2,945,000	3,166,000
Weighted average grant date fair value per award [Roll Forward]
Weighted average grant date fair value of restricted stock awards - beginning of period (in dollars per share) | $ / shares	$ 61
Weighted average grant date fair value of restricted stock awards - shares granted (in dollars per share) | $ / shares	70
Weighted average grant date fair value of restricted stock awards - shares vested (in dollars per share) | $ / shares	58
Weighted average grant date fair value of restricted stock awards - shares forfeited (in dollars per share) | $ / shares	59
Weighted average grant date fair value of restricted stock awards - end of period (in dollars per share) | $ / shares	$ 66	$ 61
Summary of stock option plan activity [Roll Forward]
Options - beginning balance (in shares)	43,920,000
Granted (in shares)	9,163,000
Exercised (in shares)	(8,903,000)
Forfeited or expired (in shares)	(488,000)
Options - ending balance (in shares)	43,692,000	43,920,000
Options exercisable (in shares)	26,396,000
Additional disclosures pertaining to stock options [Abstract]
Weighted average exercise price of options - beginning of period (in dollars per share) | $ / shares	$ 56
Weighted average exercise price of options - shares granted (in dollars per share) | $ / shares	73
Weighted average exercise price of options - shares exercised (in dollars per share) | $ / shares	46
Weighted average exercise price of options - shares forfeited or expired (in dollars per share) | $ / shares	60
Weighted average exercise price of options - end of period (in dollars per share) | $ / shares	61	$ 56
Weighted average exercise price of options exercisable - end of period (in dollars per share) | $ / shares	$ 57
Weighted average remaining contractual life, options outstanding (in years)	4 years
Weighted average remaining contractual life, options exercisable (in years)	3 years
Value of unexercised in-the-money options, options outstanding | $	$ 261
Value of unexercised in-the-money options, options exercisable | $	236
Stock-based compensation, additional disclosures [Abstract]
Benefits of tax deductions, excess of grant date fair value, exercise of stock options and vesting of RSU awards | $	59	$ 55	$ 63
Cash proceeds received from options exercised | $	$ 386	299	314
Incentive Stock Plans
Additional disclosures pertaining to stock based compensation [Abstract]
Number of shares available for grant (in shares)	10,750,000
Unrecognized compensation expense | $	$ 56
Unrecognized compensation expense, weighted-average period of recognition in years	2 years 1 month 6 days
Total fair value of shares vested | $	$ 61	70	71
Stock-based compensation, additional disclosures [Abstract]
Vesting period (in years)	3 years
Stock Option Plans
Additional disclosures pertaining to stock based compensation [Abstract]
Number of shares available for grant (in shares)	28,401,438
Unrecognized compensation expense | $	$ 49
Unrecognized compensation expense, weighted-average period of recognition in years	1 year 8 months 12 days
Stock-based compensation, additional disclosures [Abstract]
Contractual term (in years)	6 years
Vesting period (in years)	3 years
Total intrinsic value of options exercised | $	$ 221	$ 200	$ 211
Program 2015
Stock Repurchases [Abstract]
Stock repurchase program, authorized amount | $				$ 5,000