Equity (Assumptions and Options) (Details) - Employee Stock Option [Member] - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assumptions used to estimate the fair value of options using the Black-Scholes option pricing model [Abstract]
Expected volatility (in hundredths)	14.41%	14.91%	16.37%
Expected dividends (in hundredths)	3.05%	3.16%	3.16%
Expected term (years)	7 years	7 years	7 years
Risk-free rate (in hundredths)	2.83%	2.23%	1.50%
Option activity [Roll Forward]
Shares underlying options - Balance at beginning of year (in shares)	2,483,022
Shares underlying options - Granted (in shares)	330,071
Shares underlying options - Exercised (in shares)	(317,463)
Shares underlying options - Balance at end of year (in shares)	2,495,630	2,483,022
Shares underlying options - Exercisable (in shares)	1,800,897
Additional disclosures pertaining to options [Abstract]
Balance at beginning of year, weighted average exercise price (in dollars per share)	$ 83.45
Granted, weighted average exercise price (in dollars per share)	154.43
Exercised, weighted average exercise price (in dollars per share)	55.94
Balance at end of year, weighted average exercise price (in dollars per share)	96.33	$ 83.45
Exercisable at end of year, weighted average exercise price (in dollars per share)	$ 80.29
Balance at end of year, weighted average remaining contractual term (years)	5 years 7 months 6 days
Exercisable at end of year, weighted average remaining contractual term (years)	4 years 6 months
Balance at end of year, aggregate intrinsic value	$ 193
Exercisable at end of year, aggregate intrinsic value	$ 168
Granted, weighted average grant date fair value (in dollars per share)	$ 18.05	$ 13.25	$ 11.74
Total intrinsic value of stock options exercised	$ 35,000,000	$ 41,000,000	$ 42,000,000
Cash received from option exercises	18,000,000	23,000,000	36,000,000
Tax benefit realized from options exercised	$ 9,000,000	$ 16,000,000	$ 16,000,000