Segment Data - Revenues by Geographic Areas (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total Revenues	$ 3,067	$ 2,051	$ 6,054	$ 4,102
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total Revenues	1,719	863	3,410	1,744
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Total Revenues	$ 1,349	$ 1,188	$ 2,644	$ 2,358