Accounts Receivable (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Receivables [Abstract]
Trade accounts receivable	$ 1,303	$ 1,359
Other accounts receivable	83	91
Accounts receivable — third parties	1,386	1,450
Allowance for doubtful accounts — third parties	(4)	(3)	(5)	(7)
Accounts receivable, net — third parties	1,382	1,447
Accounts receivable - related parties	$ 54	$ 38