Stock-Based Compensation - Activity (Detail) - $ / shares	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued under equity compensation plans (in shares)	820,000	642,000	2,256,000	5,248,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted stock options (in shares)	131,000	190,000	246,000	929,000
Weighted average grant-date fair value, options (in dollars per share)	$ 13.43	$ 30.52	$ 15.81	$ 39.28
Restricted Stock Units (RSU)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	316,000	152,000	712,000	558,000
Weighted average grant-date fair value, RSUs (in dollars per share)	$ 28.00	$ 57.27	$ 31.80	$ 54.49

The number of grants made 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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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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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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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Net number of share options (or share units) granted during the period.

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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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Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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