Significant Transactions (Details) (USD $)	6 Months Ended		12 Months Ended	6 Months Ended	3 Months Ended			12 Months Ended			3 Months Ended
	Jul. 10, 2013	Jul. 09, 2013	Jun. 30, 2014	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2015	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2015	Oct. 22, 2012	May 16, 2014	Apr. 30, 2015	Apr. 24, 2015	Apr. 10, 2015
Business Acquisition [Line Items]
Business Combination, Equity Interest in Acquiree, Remeasurement Net Gain excluded in Pro Forma Financial Results	$ 1,400,000,000
Business Combination Acquisition Related Costs excluded in Pro Forma Financial Results	169,000,000
Clearwire Acquisition [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired		3,500,000,000
Cash Acquired from Acquisition		198,000,000
Cash consideration accrued for dissenting shares relating to stockholders who exercised their right to appraisal		125,000,000
Payments to Acquire Businesses, Gross		3,700,000,000
Goodwill, Purchase Accounting Adjustments			269,000,000
SoftBank Merger [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	14,100,000,000
Cash Acquired from Acquisition	2,500,000,000
Payments to Acquire Businesses, Gross	16,600,000,000
Equity Method Investments, Fair Value Disclosure		3,300,000,000
Conversion of Sprint vested stock-based awards upon acquisition	193,000,000	59,000,000
Goodwill, Purchase Accounting Adjustments			476,000,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	22.00%							21.00%			21.00%
Convertible Debt												3,100,000,000
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								79.00%			79.00%
Issuance of common stock to stockholders upon acquisition	5,300,000,000
Capital contribution by SoftBank	5,000,000,000
Business combination, cost of acquired entity, additional partial cash paid	1,900,000,000
SoftBank Merger [Member] | Other Intangible Assets [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles				300,000,000
Successor [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired					0	0	0	0	14,112,000,000
Conversion of Sprint vested stock-based awards upon acquisition									193,000,000
Issuance of common stock to stockholders upon acquisition									5,344,000,000
Predecessor [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	4,039,000,000					0				0
deferred tax liability [Member] | Clearwire Acquisition [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities				270,000,000
Accounts Receivable [Member]
Business Acquisition [Line Items]
Accounts Receivable Facility, Expiration Period								2 years
Maximum funding limit													1,300,000,000
Receivables Facility, Amount of Funds Available								500,000,000			500,000,000
Receivables contributed by the Originators to the SPEs								3,500,000,000			3,500,000,000
Derecognized assets, gross								1,800,000,000			1,800,000,000
Cash received for sale of receivables under receivables facility											500,000,000
Receivable from Conduits								1,300,000,000			1,300,000,000
Transfers of financial assets accounted for as a sale, initial fair value of assets obtained as proceeds								1,200,000,000			1,200,000,000
Pledged Financial Instruments and Other Assets, Not Separately Reported on Statement of Financial Position, Description								1.7
Subsequent Event [Member] | Accounts Receivable [Member]
Business Acquisition [Line Items]
Maximum funding limit															3,300,000,000
Installment Receivables added to Receivables Facility Availability															2,000,000,000
Receivables Facility, Amount of Funds Available														1,400,000,000
Funded Balance																$ 0