Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Stock-based compensation awards
Required minimum age of a participant upon separation from service to meet the criteria for Long Service Separation (in years)	55 years
Minimum term of service to meet criteria for Long Service Separation (in years)	5 years
Stock-based compensation expense, before tax (in dollars)	$ 49	$ 101
Assumptions used in determining the fair value of the stock-based awards
Weighted-average dividend yield (as a percent)	3.42%	3.23%
Weighted-average volatility (as a percent)	29.20%	31.10%
Volatilities, low end of range (as a percent)	22.10%	22.50%
Volatilities, high end of range (as a percent)	33.00%	33.40%
Risk-free interest rates, low end of range (as a percent)	0.81%	0.62%
Risk-free interest rates, high end of range (as a percent)	2.35%	1.73%
Weighted-average expected lives (in years)	8 years	8 years
Unrecognized compensation cost related to nonvested stock-based compensation awards (in dollars)	$ 306
Term of amortization of unrecognized compensation cost over weighted-average remaining requisite service periods (in years)	1 year 9 months
Stock Options
Stock-based compensation awards
Shares Granted (in shares)	2,701,644	4,243,272
Weighted-Average Fair Value Per Share (in dollars per share)	$ 25.01	$ 20.64
Weighted-Average Grant Date Stock Price (in dollars per share)	95.66	74.77
RSUs
Stock-based compensation awards
Weighted-Average Grant Date Stock Price (in dollars per share)	$ 95.63	$ 74.77
Shares Granted (in shares)	906,068	1,085,505
Weighted-Average Fair Value Per Share (in dollars per share)	$ 89.76	$ 68.04
PRSUs
Stock-based compensation awards
Weighted-Average Grant Date Stock Price (in dollars per share)	$ 95.66	$ 74.77
Shares Granted (in shares)	437,385	614,347
Weighted-Average Fair Value Per Share (in dollars per share)	$ 86.78	$ 64.71

The stock price per share on the grant date for issuance to employees under the plan.

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- Definition

Represents the minimum term of service to meet the criteria for a Long Service Separation.

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- Definition

Represents the required minimum age of a participant upon separation from service to meet the criteria for a Long Service Separation.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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- Definition

The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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- Definition

The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

Weighted average expected volatility rate of share-based compensation awards.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Net number of non-option equity instruments granted to participants.

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- Definition

Gross number of share options (or share units) granted during the period.

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- Definition

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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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

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