Significant Transactions (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended			6 Months Ended			12 Months Ended
	Oct. 31, 2015	Sep. 30, 2015	Mar. 31, 2016	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Jul. 10, 2013	Jul. 09, 2013	Mar. 31, 2016	Mar. 31, 2015	Jun. 30, 2014	Dec. 31, 2013	Nov. 30, 2015	Oct. 22, 2012
Business Acquisition [Line Items]
Business Combination, Equity Interest in Acquiree, Remeasurement Net Gain excluded in Pro Forma Financial Results							$ 1,400
Business Combination Acquisition Related Costs excluded in Pro Forma Financial Results							169
Maximum funding limit													$ 4,300
Receivables Facility, Amount of Funds Available			$ 94						$ 94
Derecognized assets, gross		$ 1,900
Cash received for sale of receivables under receivables facility	$ 300	400	125
Receivable from Conduits		1,500	$ 116						$ 116	$ 0
Transfers of financial assets accounted for as a sale, initial fair value of assets obtained as proceeds		$ 1,400								1,200
Clearwire Acquisition [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired								$ 3,500
Cash Acquired from Acquisition								198
Cash consideration accrued for dissenting shares relating to stockholders who exercised their right to appraisal								125
Payments to Acquire Businesses, Gross								3,700
Goodwill, Purchase Accounting Adjustments											$ 269
SoftBank Merger [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired							14,100
Cash Acquired from Acquisition							2,500
Payments to Acquire Businesses, Gross							16,600
Equity Method Investments, Fair Value Disclosure								3,300
Conversion of Sprint vested stock-based awards upon acquisition							$ 193	$ 59
Goodwill, Purchase Accounting Adjustments											$ 476
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners			17.00%				22.00%		17.00%
Convertible Debt														$ 3,100
Debt instrument, interest rate, stated percentage														1.00%
Stock Issued During Period, Shares, Conversion of Convertible Securities							590,476,190
Debt Instrument, Convertible, Conversion Price							$ 5.25
Business Acquisition, Percentage of Voting Interests Acquired			83.00%						83.00%
Issuance of common stock to stockholders upon acquisition							$ 5,300
Capital contribution by SoftBank							5,000
Business combination, cost of acquired entity, additional partial cash paid							1,900
SoftBank Merger [Member] | Other Intangible Assets [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles						$ 300
Successor [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired				$ 0	$ 0				$ 0	$ 0		$ 14,112
Conversion of Sprint vested stock-based awards upon acquisition												193
Issuance of common stock to stockholders upon acquisition												$ 5,344
Predecessor [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired					$ 0		$ 4,039
deferred tax liability [Member] | Clearwire Acquisition [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities						$ 270