Other Expense (Income) (Details) MYR in Millions, $ in Millions	3 Months Ended										12 Months Ended
	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 MYR	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Foreign currency remeasurement losses (gains), net											$ (5)	$ (2)	$ 27
(Gain) loss on change in fair value of other unrealized derivative instruments, net											(5)	4	0
Loss (gain) on change in fair value of other realized derivative instruments, net											61	(64)	2
Loss on sale of assets, net											6	4	5
Loss on sale of business											27	0	0
Loss on Brazilian tax litigation, net											5	5	7
Interest income											(11)	(13)	(7)
Gain on business interruption insurance recovery, net						$ (6)				$ (13)	0	(10)	(19)
Other, net											17	8	2
Other expense (income), net	$ 32	$ (3)		$ 38	$ 28	$ 10	$ (16)	$ (32)	$ (30)		$ 95	$ (68)	$ 17
Aluminum Company of Malaysia Berhad (ALCOM) [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership Percentage				59.15%
Proceeds from Divestiture of Businesses		$ 12	MYR 48