Additional Financial Information - Components of Other, Net (Parenthetical) (Detail) - USD ($) $ in Millions		1 Months Ended	3 Months Ended
		Aug. 31, 2014	Sep. 30, 2015	Sep. 30, 2014
Components of Other Income (Expense) [Line Items]
Gain on sale of marketable securities	[1]		$ 0	$ 29
REA Group Inc [Member]
Components of Other Income (Expense) [Line Items]
Cash consideration on sale of marketable securities		$ 104
Gain on sale of marketable securities			$ 29

[1] In August 2014, REA Group completed the sale of a minority interest held in marketable securities for total cash consideration of $104 million. As a result of the sale, REA Group recognized a pre-tax gain of $29 million, which was reclassified out of accumulated other comprehensive income and included in Other, net in the Statement of Operations.