Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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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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Share-based Compensation - Awards Granted to Company Employees and Non-employee Directors Under the 2007 Equity Incentive Compensation Plan (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Non-qualified stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			1,247,982
Weighted-Average Grant Date Fair Value (in dollars per share)			$ 29.37
Weighted-Average Exercise Price (in USD per share)			$ 182.50
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			2,264,886
Weighted-Average Grant Date Fair Value (in dollars per share)			$ 183.27
Performance-bases shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			470,128
Weighted-Average Grant Date Fair Value (in dollars per share)			$ 211.08
Equity Incentive Compensation Plan, 2007
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation cost	$ 93	$ 106	$ 204	$ 201