Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended	12 Months Ended
	Sep. 30, 2014	Mar. 31, 2014
Statement of Financial Position [Abstract]
Allowances for accounts receivable	$ 4	$ 4
Common stock, par value (in usd per share)
Common stock, shares authorized	unlimited	unlimited
Common stock, shares issued	1,000	1,000
Common stock, shares outstanding	1,000	1,000