Stock-Based Compensation Plans (Summary Of Stock Option Award Activity) (Detail) - Stock Options - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of options exercised	$ 44	$ 75	$ 14
Unrecognized compensation cost	$ 10
Weighted average recognition period, in years	1 year 2 months 14 days
Number of Shares
Outstanding, beginning balance	8,465,398
Granted	903,797
Converted in acquisition	302,403
Exercised	(916,566)
Forfeited or expired	(30,437)
Outstanding, ending balance	8,724,595	8,465,398
Vested and expected to vest at December 31, 2018 (in shares)	8,707,148
Exercisable at December 31, 2018 (in shares)	6,586,859
Weighted Average Exercise Price
Outstanding, beginning balance (in USD per share)	$ 33.74
Granted (in USD per share)	67.71	$ 50.57	$ 35.27
Converted in acquisition (in USD per share)	7.00
Exercised (in USD per share)	26.24
Forfeited or expired (in USD per share)	48.96
Outstanding, ending balance (in USD per share)	37.07	$ 33.74
Vested and expected to vest at December 31, 2018 (in USD per share)	37.01
Exercisable at December 31, 2018 (in USD per share)	$ 31.42
Weighted Average Remaining Contractual Terms (in years)
Vested and expected to vest at December 31, 2018 (in years)	5 years 1 month
Exercisable at December 31, 2018 (in years)	4 years
Aggregate Intrinsic Value (in millions)
Vested and expected to vest at December 31, 2018 (in USD)	$ 199
Exercisable at December 31, 2018 (in USD)	$ 182

Share-based Compensation Arrangement by Share-based Payment Award, Options, Aggregate Intrinsic Value [Abstract]

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Share-based Compensation Arrangement by Share-based Payment Award, Options, Converted in Acquisition

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Share-based Compensation Arrangement by Share-based Payment Award, Options, Weighted Average Remaining Contractual Term [Abstract]

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Share-based Compensation Arrangements by Share-based Payment Award, Options, Converted in Acquisition, Weighted Average Exercise Price

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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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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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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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For presentations that combine terminations, 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 or that expired.

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Weighted average price of options that were either forfeited or expired.

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

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

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Number of fully vested and expected to vest exercisable options that may be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of share options (or share units) exercised during the current period.

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