Share-Based Compensation - Stock Options Status and Activity (Detail) - Stock Option - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Under Option Outstanding Beginning Balance (in shares)	293,997
Granted (in shares)	0
Exercised (in shares)	(8,438)
Forfeited (in shares)	(12,689)
Shares Under Option Outstanding Ending Balance (in shares)	272,870	293,997
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Prices, Outstanding, Beginning Balance (in dollars per share)	$ 46.89
Granted (in dollars per share)	0
Exercised (in dollars per share)	29.08
Forfeited (in dollars per share)	42.90
Weighted Average Exercise Prices, Outstanding, Ending Balance (in dollars per share)	$ 47.41	$ 46.89
Weighted Average Remaining Life in Years	15 days	1 year 4 months 24 days
Aggregate Intrinsic Value, Outstanding, Beginning Balance	$ 0
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 0	$ 0

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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- Definition

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

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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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- Definition

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

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-Publisher FASB
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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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- Definition

Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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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 option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

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