Long-Term Debt, Financing and Capital Lease Obligations (Narrative) (Details)	1 Months Ended				3 Months Ended		12 Months Ended
	Feb. 28, 2017	Oct. 31, 2016 USD ($)	May 31, 2016 USD ($)	Apr. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) site years	Jun. 30, 2016 USD ($)	Mar. 31, 2017 USD ($)	May 09, 2017	Feb. 02, 2017 USD ($)	Nov. 30, 2015 USD ($)	Dec. 31, 2014 USD ($) tranche
Schedule of Capitalization, Long-term Debt [Line Items]
Maximum Funding Limit										$ 4,300,000,000
Receivables Facility, maximum amount available based on receivables sold to investors, percent					50.00%
Receivables Facility, Amount Outstanding					$ 2,600,000,000
Receivables Facility, Amount of Funds Available					110,000,000
Receivables Facility, Amount Drawn on Facility					765,000,000
Sale Leaseback Transaction, Cumulative Lease Payments					125,000,000
Long-term debt issued by 100% owned subsidiary and is fully and unconditionally guaranteed by the parent					23,300,000,000
Interest Costs Capitalized					15,000,000	$ 10,000,000
Cash interest payments					700,000,000	600,000,000
Redeemable notes					28,700,000,000
Principal amount of notes with the right to require the Company to repurchase on change of control					22,500,000,000
Call premiums paid on debt redemptions					129,000,000	0
Gain (Loss) on Extinguishment of Debt					$ (66,000,000)	0
Long-term Debt, Gross									$ 6,000,000,000
Long-term Debt, Percentage Bearing Variable Interest, Amount									250
Number of cell sites leased back | site					3,000
Term in years for cell sites leased back renewal options | years					20
Payments for (Proceeds from) Businesses and Interest in Affiliates			$ 181,000,000
Ratio Of Total Indebtedness To Adjusted EBITDA					2.5
cash paid to purchasers under receivables facility						185,000,000
Financing Receivable, Net					$ 1,792,000,000		$ 1,764,000,000
Installment Lease Receivables, Net Book Value					3,200,000,000
Capital Lease Obligations [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross					324,000,000		3,016,000,000
Network Sale-Leaseback [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Sale Leaseback Transaction, Net Book Value				$ 3,000,000,000	2,200,000,000
Sale Leaseback Transaction, Net Proceeds, Financing Activities				2,200,000,000
Long-term Debt and Capital Lease Obligations, Repayments of Principal in Next Twelve Months					1,800,000,000
Repayments of Debt					117,000,000
Handset Sale-Leaseback Tranche 2 [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Sale Leaseback Transaction, Net Book Value			$ 1,300,000,000		470,000,000
Sale Leaseback Transaction, Net Proceeds, Investing Activities				1,100,000,000
Receivables from sale-leaseback				$ 186,000,000
Repayments of Debt					158,000,000
Handset Sale-Leaseback Tranche 1 [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Sale Leaseback Transaction, Monthly Rental Payments						197,000,000
Tower financing [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Sale Leaseback Transaction, Net Book Value					$ 200,000,000
Minimum [Member] | Capital Lease Obligations [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					2.35%
Spectrum Assets [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Concentration Risk, Percentage		14.00%
Shentel [Member] | Capital Lease Obligations [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross					$ 158,000,000
Handset Sale-Leaseback Tranche 2 [Member] | MLS 2nd Tranche [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Sale Leaseback Transaction, Net Book Value					227,000,000
Delcredere / Ducroire (D/D) Secured Equipment Credit Facility [Member] | Line of Credit [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity											$ 250,000,000
Repayments of Lines of Credit					3,000,000
Line of Credit Facility, Amount Outstanding					29,000,000
K-sure Secured Equipment Credit Facility [Member] | Line of Credit [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity											$ 750,000,000
Repayments of Lines of Credit					33,000,000
Number of tranches | tranche											3
Line of Credit Facility, Amount Outstanding					226,000,000
Finnvera Secured Equipment Credit Facility [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Line of Credit Facility, Increase (Decrease), Net					92,000,000
Finnvera Secured Equipment Credit Facility [Member] | Line of Credit [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity											$ 800,000,000
Repayments of Lines of Credit					57,000,000
Number of tranches | tranche											1
Line of Credit Facility, Amount Outstanding					175,000,000
Export Development Canada Agreement [Member] | Line of Credit [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Line of Credit Facility, Amount Outstanding							300,000,000
Export Development Canada Agreement [Member] | Tranche three and four [Member] | Line of Credit [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Line of Credit Facility, Amount Outstanding					300,000,000
Secured Revolving Bank Credit Facility expires in Feb 2021[Member] [Member] | Revolving Credit Facility [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity									$ 2,000,000,000
Line of Credit Facility, Remaining Borrowing Capacity					1,800,000,000
Line of Credit Facility, Amount Outstanding					0		0
Ratio Of Total Indebtedness To Adjusted EBITDA									6.0
Ratio Of Total Indebtedness To Adjusted EBITDA, Minimum									3.5
Secured Revolving Bank Credit Facility expires in Feb 2021[Member] [Member] | Letter of Credit [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Letters of Credit Outstanding, Amount					$ 192,000,000
Sprint Nextel Corporation [Member] | Secured Debt [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					9.25%
Long-term Debt, Gross					$ 200,000,000		200,000,000
Sprint Nextel Corporation [Member] | Secured term loan [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross									$ 4,000,000,000
Line of Credit Facility, Amount Outstanding					3,990,000,000		4,000,000,000
Debt Instrument, Term	7 years
Sprint Nextel Corporation [Member] | Senior Notes [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross					5,692,000,000		6,080,000,000
Sprint Nextel Corporation [Member] | Guaranteed notes [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross					$ 2,800,000,000		4,000,000,000
Sprint Nextel Corporation [Member] | Minimum [Member] | Senior Notes [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					6.00%
Sprint Nextel Corporation [Member] | Minimum [Member] | Guaranteed notes [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					7.00%
Spectrum Financing [Member] | Secured Debt [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Maximum Borrowing Capacity		$ 7,000,000,000
Debt Instrument, Additional Borrowings Available		$ 3,500,000,000
Sprint Spectrum Co LLC, Sprint Spectrum Co II LLC, Sprint Spectrum Co III LLC [Member] | Secured Debt [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.36%			3.36%
Long-term Debt, Gross					$ 3,500,000,000		3,500,000,000
Debt instrument face amount		$ 3,500,000,000
Debt Instrument, Term		5 years
Secured Debt, Current					656,000,000
Notes due 2017 and Guaranteed Notes Due 2018 [Member] | Senior Notes [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Call premiums paid on debt redemptions					130,000,000
Debt Instrument, Unamortized Premium					64,000,000
Gain (Loss) on Extinguishment of Debt					66,000,000
Guaranteed Notes Due 2018 [Member] | Senior Notes [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage								9.00%
Repayments of Debt					1,200,000,000
Notes due 2017 [Member] | Senior Notes [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage								8.375%
Repayments of Debt					388,000,000
Sprint Corporation [Member] | Senior Notes [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross					$ 10,500,000,000		10,500,000,000
Sprint Corporation [Member] | Minimum [Member] | Senior Notes [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					7.13%
Wireless Service [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Purchase Commitment Allocation					33.00%
Installment Receivables [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Purchase Commitment Allocation					39.00%
Future lease receivables [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Purchase Commitment Allocation					28.00%
Financing Receivable
Schedule of Capitalization, Long-term Debt [Line Items]
Cash received for sale of receivables under receivables facility						40,000,000
Cash Flows Between Transferor and Transferee, Proceeds from Collections Reinvested in Revolving Period Transfers						$ 28,000,000
Accounts and notes receivable, net
Schedule of Capitalization, Long-term Debt [Line Items]
Financing Receivable, Net					$ 1,303,000,000		1,195,000,000
Accounts and notes receivable, net | Wireless Services and Installment Receivables [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Financing Receivable, Net					3,000,000,000
Other assets
Schedule of Capitalization, Long-term Debt [Line Items]
Financing Receivable, Net					489,000,000		$ 569,000,000
Interest Rate Swap [Member] | Sprint Nextel Corporation [Member] | Secured term loan [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative, Notional Amount									$ 2,000,000,000
Derivative Liability, Fair Value, Gross Liability					$ 10,400,000
Derivative, Term of Contract							5 years