Long-Term Incentive Employee Compensation Rollforward of Outstanding Stock Options (Detail) - $ / shares shares in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock Options Outstanding Rollforward - Shares
Outstanding – January 1	0.9	1.4	1.7
Granted			0.4
Exercised	(0.2)	(0.5)	(0.6)
Forfeited or expired			(0.1)
Outstanding – December 31	0.7	0.9	1.4
Options exercisable – December 31	0.5	0.5	0.8
Stock Options Outstanding Rollforward - Weighted Average Exercise Price
Outstanding – January 1	$ 34.07	$ 30.57	$ 27.10
Granted	0	0	33.01
Exercised	30.52	22.95	20.88
Forfeited or expired	0	0	39.03
Outstanding – December 31	35.04	34.07	30.57
Options exercisable – December 31	$ 36.04	$ 32.24	$ 24.41

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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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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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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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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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Number of share options (or share units) exercised during the current period.

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