Related Party Transactions (Schedule of Related Party Transactions) (Details) - USD ($) $ in Millions	12 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Related Party Transaction [Line Items]
Cost of equipment sales	$ 6,109	$ 6,583	$ 5,518
Brightstar [Member]
Related Party Transaction [Line Items]
Accounts Receivable, Related Parties	188	367
Accounts Payable, Related Parties, Current	88	160
Revenue from Related Parties	1,922	1,682	1,731
Cost of equipment sales	$ 1,986	$ 1,600	$ 1,743

Cost of equipment sales

No definition available.

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- Definition

Amount for accounts payable to related parties. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

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- Definition

For an unclassified balance sheet, amount of receivables arising from transactions with related parties.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

+ References

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