Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
		Dec. 31, 2017	Jan. 30, 2018
Stockholders Equity Note [Line Items]
Stock Repurchased and Retired During Period, Shares	[1],[2]	16
Stock Repurchased and Retired During Period, Value	[2]	$ 1,778
Recovery through conversion rate adjustment		50
Stock Repurchase Remaining Authorized Amount		2,100
Dividends, Cash		$ 458
Class A common stock
Stockholders Equity Note [Line Items]
Reduction In As-Converted Stock, Shares		17
Reduction in As-Converted Stock, Average Price Per Share		$ 110.27
Subsequent Event
Stockholders Equity Note [Line Items]
Stock Repurchase Program, Authorized Amount			$ 7,500
Subsequent Event | Class A common stock
Stockholders Equity Note [Line Items]
Dividends Payable, Amount Per Share			$ 0.210

[1] All shares repurchased in the open market have been retired and constitute authorized but unissued shares.

[2] Shares repurchased in the open market reflect repurchases settled during the three months ended December 31, 2017. These amounts include repurchases traded but not yet settled on or before September 30, 2017 and exclude repurchases traded but not yet settled on or before December 31, 2017.