Stockholders' Equity - Additional Information (Detail) $ / shares in Units, $ in Millions			9 Months Ended
		Mar. 19, 2015	Jun. 30, 2015 USD ($)	Jul. 23, 2015 $ / shares
Stockholders Equity Note [Line Items]
Stock Repurchase Remaining Authorized Amount			$ 2,800
Dividends, Cash			$ 885
Subsequent Event
Stockholders Equity Note [Line Items]
Dividends Payable, Amount Per Share | $ / shares				$ 0.12
Class A common stock
Stockholders Equity Note [Line Items]
Stock split, conversion ratio		4
Class B common stock
Stockholders Equity Note [Line Items]
Conversion Rate Into Class A Common Stock	[1]	1.6483	1.6483
Class C common stock
Stockholders Equity Note [Line Items]
Conversion Rate Into Class A Common Stock		4	4

[1] The class B to class A common stock conversion rate is presented on a rounded basis. Conversion calculations for dividend payments are based on a conversion rate rounded to the tenth decimal.