Share-based compensation (Rollforward Of Company's Stock Options) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Number of Options [Roll Forward]
Number of option outstanding, beginning of period	9,496,856	9,449,659	10,579,507
Number of options granted	1,782,903	1,821,063	1,462,103
Number of options exercised	(1,511,948)	(1,658,671)	(2,401,869)
Number of options forfeited	(143,825)	(115,195)	(190,082)
Number of option outstanding, end of period	9,623,986	9,496,856	9,449,659
Number of options exercisable, December 31, 2014	6,313,668
Weighted-Average Exercise Price [Roll Forward]
Weighted-average exercise price of options outstanding, beginning of period (US$ oer share)	$ 61.84	$ 55.03	$ 49.78
Weighted-average exercise price of options granted (US$ per share)	$ 96.77	$ 85.41	$ 73.36
Weighted-average exercise price of options exercised (US$ per share)	$ 54.84	$ 48.17	$ 42.50
Weighted average exercise price of options forfeited (US$ per share)	$ 84.52	$ 72.50	$ 61.87
Weighted-average exercise price of options outstanding, end of period (US$ oer share	$ 69.06	$ 61.84	$ 55.03
Weighted average exercise price of options exercisable, December 31, 2014 (US$ per share)	$ 58.24
Options, Weighted-Average Fair Value and Total Intrinsic Value [Abstract]
Weighted-average fair value of stock options granted (US$ per share)	$ 18.00	$ 17.29	$ 15.58
Total intrinsic value of options exercised	$ 73	$ 70	$ 78
Total intrinsic value of options outstanding	441
Total intrinsic value of options exercisable, December 31, 2014	$ 358

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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