Stock-Based Compensation - Summary of Market-Based Shares Vesting Activity (Parenthetical) (Detail) - Market-Based Shares [Member] - Market-based [Member] $ in Millions	Sep. 30, 2019 USD ($)
Vest Date February 13, 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
TEV	$ 8,650
Vest Date February 22, 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
TEV	$ 9,350

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.

No definition available.

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