Trade and Installment Accounts Receivable (Tables)

6 Months Ended

Sep. 30, 2011

Trade and Installment Accounts Receivable [Abstract]

Components of trade and installment accounts receivable, net

	September 30,			March 31,
	2011			2011
	(in millions)
Accounts receivable — billed	$	510		$	758
Accounts receivable — unbilled		84			86
Other receivables		25			27
Less: Allowance for doubtful accounts		(18	)		(22	)
Trade accounts receivable, net	$	601		$	849