Share-Based Compensation Share-Based Compensation (Details 2) (SARs [Member]) In Millions, except Share data, unless otherwise specified	3 Months Ended			12 Months Ended		3 Months Ended	12 Months Ended
	Jun. 30, 2014	Jun. 30, 2014 Hindalco SARs [Member] USD ($)	Jun. 30, 2014 Hindalco SARs [Member] INR	Mar. 31, 2014 Hindalco SARs [Member] USD ($)	Mar. 31, 2014 Hindalco SARs [Member] INR	Jun. 30, 2014 Novelis SARs [Member] USD ($)	Mar. 31, 2014 Novelis SARs [Member] USD ($)
Number of SARs
Outstanding as of beginning of period (shares)		21,635,392	21,635,392			668,402
Granted (shares)		4,868,698	4,868,698			376,173
Exercised (shares)		(4,128,272)	(4,128,272)			(12,244)
Forfeited/Cancelled (shares)		(730,823)	(730,823)			(33,760)
Outstanding as of end of period (shares)		21,644,995	21,644,995	21,635,392	21,635,392	998,571	668,402
Shares exercisable as of end of period		8,339,534	8,339,534			223,623
Weighted Average Exercise Price
Outstanding as of beginning of period			112.26			$ 90.09
Granted			145.50			$ 94.40
Exercised			89.97			$ 66.46
Forfeited/Cancelled			131.29			$ 83.77
Outstanding as of end of period			123.35		112.26	$ 92.22	$ 90.09
Exercisable as of end of period			121.52			$ 89.00
Weighted Average Remaining Contractual Term, Outstanding as of beginning of period		4 years 11 months	4 years 11 months	4 years 4 months	4 years 4 months	5 years 9 months	5 years 4 months
Weighted Average Remaining Contractual Term, Granted	7 years	7 years 0 months	7 years 0 months			7 years 0 months
Weighted Average Remaining Contractual Term, Outstanding as of end of period		4 years 11 months	4 years 11 months	4 years 4 months	4 years 4 months	5 years 9 months	5 years 4 months
Weighted Average Remaining Contractual Term, Exercisable as of end of period		3 years 4 months	3 years 4 months			4 years 10 months
Aggregate Intrinsic Value, Outstanding as of beginning of period		$ 13				$ 2
Aggregate Intrinsic Value, Granted		0				0
Aggregate Intrinsic Value, Outstanding as of end of period		17		13		4	2
Aggregate Intrinsic Value, Exercisable as of end of period		$ 8				$ 2