Leases - Schedule of Future Minimum Rental Payments in Respect of Non-cancellable Operating Leases (Details) - USD ($) $ in Millions	Mar. 31, 2018	Mar. 31, 2017
Less Than 1 Year
Disclosure Of Finance Lease And Operating Lease By Lessee [Line Items]
Future minimum rental payments in respect of non-cancellable operating leases	$ 70	$ 71
Due in a period between one year and five years
Disclosure Of Finance Lease And Operating Lease By Lessee [Line Items]
Future minimum rental payments in respect of non-cancellable operating leases	213	191
Due after five years
Disclosure Of Finance Lease And Operating Lease By Lessee [Line Items]
Future minimum rental payments in respect of non-cancellable operating leases	$ 134	$ 114

The amount of future minimum lease payments payable under non-cancellable operating leases. Minimum lease payments are payments over the lease term that the lessee is or can be required to make, excluding contingent rent, costs for services and taxes to be paid by, and reimbursed to, the lessor, together with: (a) for a lessee, any amounts guaranteed by the lessee or by a party related to the lessee; or (b) for a lessor, any residual value guaranteed to the lessor by: (i) the lessee; (ii) a party related to the lessee; or (iii) a third party unrelated to the lessor that is financially capable of discharging the obligations under the guarantee.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2019-01-01
-Name IAS
-Number 17
-IssueDate 2017-01-01
-Paragraph 35
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=17&date=2017-03-02&anchor=para_35_a&doctype=Standard&book=B
-URIDate 2017-03-09

Name:	ifrs-full_MinimumLeasePaymentsPayableUnderNoncancellableOperatingLease
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant