Equity (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Equity stock-based compensation
Shares Authorized Under Stock Incentive Plan	8,000,000
Shares available for future grants under Stock Incentive Plan	2,800,000
Total share-based compensation expense included in net income	$ 12	$ 12	$ 11
Income tax benefit related to share-based compensation included in net income	5	5	5
Stock Option Awards
Equity stock-based compensation
Term of options	10 years
Period of vesting	3 years
Weighted-average grant date fair value of stock options granted (in dollars per share)	$ 17.87	$ 16.16	$ 15.17
Assumptions used to measure the fair value of awards
Expected life	5 years 9 months 18 days	5 years 9 months 18 days	5 years 9 months 18 days
Risk-free interest rate (as a percent)	1.10%	1.10%	2.80%
Expected volatility (as a percent)	32.60%	33.30%	32.70%
Expected dividend yield (as a percent)	1.60%	1.20%	1.20%
Stock option activity
Outstanding at the beginning of the period (in shares)	3,032,000	4,030,000	4,434,000
Granted (in shares)	416,000	460,000	438,000
Exercised (in shares)	(511,000)	(1,409,000)	(777,000)
Cancelled (in shares)	(88,000)	(49,000)	(65,000)
Outstanding at the end of the period (in shares)	2,849,000	3,032,000	4,030,000	4,434,000
Stock Option Price Range
Options outstanding at the beginning of the period, price range, lower range limit (in dollars per share)	$ 24.70	$ 16.92	$ 14.33	$ 14.17
Options outstanding at the beginning of the period, price range, Upper range limit (in dollars per share)	$ 66.26	$ 57.33	$ 52.64	$ 40.71
Granted, low end of range (in dollars per share)	$ 66.07	$ 55.95	$ 47.95
Granted, high end of range (in dollars per share)	$ 66.26	$ 57.33	$ 52.64
Exercised, low end of range (in dollars per share)	$ 16.92	$ 14.33	$ 14.17
Exercised, high end of range (in dollars per share)	$ 57.33	$ 47.95	$ 40.71
Cancelled, low end of range (in dollars per share)	$ 47.95	$ 25.58	$ 18.31
Cancelled, high end of range (in dollars per share)	$ 66.07	$ 55.95	$ 47.95
Options outstanding at the end of the period, price range, lower range limit (in dollars per share)	$ 24.70	$ 16.92	$ 14.33	$ 14.17
Options outstanding at the end of the period, price range, Upper range limit (in dollars per share)	$ 66.26	$ 57.33	$ 52.64	$ 40.71
Share options, weighted average exercise price
Outstanding at the beginning of the period (in dollars per share)	$ 35.66	$ 30.29	$ 27.49
Granted (in dollars per share)	$ 66.07	$ 55.96	$ 47.96
Exercised (in dollars per share)	$ 28.74	$ 26.80	$ 24.24
Cancelled (in dollars per share)	$ 54.37	$ 39.29	$ 30.60
Outstanding at the end of the period (in dollars per share)	$ 40.77	$ 35.66	$ 30.29	$ 27.49
Additional information pertaining to stock options
Total intrinsic value of stock options exercised	20	46	22
Cash received from exercise of stock options	14	34	18
Excess tax benefit realized from exercise of stock options	5	11	6
Unrecognized compensation cost	$ 8
Weighted-average period for amortization of unrecognized compensation cost	1 year 8 months 12 days