(Fair Value Measurements Using Significant Unobservable Inputs (Level 3) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended				12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Fair Value, Inputs, Level 3 [Member] Contingent consideration		Mar. 31, 2014 Fair Value, Inputs, Level 3 [Member] Contingent consideration
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance			$ 4		$ 43
Change in fair value			(2)	[1]	(35)	[1]
Payments	0	(1)	(2)	[2]	(4)	[2]
Ending Balance			$ 0		$ 4

[1] The change in fair value is reported as acquisition-related contingent consideration in our Condensed Consolidated Statements of Operations.

[2] During the six months ended September 30, 2014, we made payments totaling $2 million to settle certain performance milestones achieved in connection with one of our acquisitions. During fiscal year 2014, we made payments of $4 million to settle certain performance milestones achieved in connection with two of our acquisitions.