Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Financial Position [Abstract]
Allowances for accounts receivable	$ 6	$ 3
Common stock, par value (in usd per share)	$ 0	$ 0
Common stock, shares authorized	Unlimited	Unlimited
Common stock, shares issued	1,000	1,000
Common stock, shares outstanding	1,000	1,000