Equity - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions		1 Months Ended	6 Months Ended
	Jan. 29, 2016	Aug. 31, 2015	Dec. 31, 2015	May. 31, 2013
Class of Stock [Line Items]
Dividend declaration date			2015-08
Dividend payable date			Oct. 21, 2015
Dividend record date			Sep. 16, 2015
Subsequent Event [Member]
Class of Stock [Line Items]
Remaining authorized amount under stock repurchase program	$ 439,000,000
Class A Common Stock [Member]
Class of Stock [Line Items]
Aggregate amount of shares authorized to be repurchased				$ 500,000,000
Cash dividend declared		$ 0.10
Class A Common Stock [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Number of shares repurchased	4.3
Aggregate cost of shares repurchased	$ 61,000,000
Class B Common Stock [Member]
Class of Stock [Line Items]
Cash dividend declared		$ 0.10