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Debt Instrument, Number of Extension Options

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Debt Instrument, Registration Rights Agreement, Maximum Interest Increase

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Debt Instrument, Term Preceding Maturity Date

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Face (par) amount of debt instrument at time of issuance.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Contractual interest rate for funds borrowed, under the debt agreement.

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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.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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The cash outflow for loan and debt issuance costs.

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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

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The cash inflow from a borrowing with the highest claim on the assets of the entity in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle, if longer).

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Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

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Debt - Credit Facility and Senior Notes Narrative (Details)							3 Months Ended	12 Months Ended
	Jan. 14, 2021 USD ($)	Oct. 30, 2020 USD ($) option	Oct. 28, 2020 USD ($)	Oct. 06, 2020 USD ($)	Apr. 09, 2020 USD ($)	Apr. 01, 2020 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 16, 2020 USD ($)	Jun. 24, 2020 USD ($)	Mar. 31, 2018 USD ($)
Debt Instrument [Line Items]
Effective interest rate								4.60%	5.20%
Average debt outstanding during period								$ 58,400,000,000	$ 25,500,000,000
Principal Issuances								54,750,000,000
Payments of consent fees								109,000,000	$ 0	$ 0
Proceeds from issuance of senior long-term debt			$ 4,600,000,000	$ 4,000,000,000.0				$ 54,080,000,000
Subsequent Event
Debt Instrument [Line Items]
Proceeds from issuance of senior long-term debt	$ 3,000,000,000.0
Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Financing commitment, amount											$ 5,500,000,000
Senior Notes
Debt Instrument [Line Items]
Principal Issuances			$ 4,750,000,000	$ 4,000,000,000.0	$ 19,000,000,000.0							$ 4,000,000,000.0
Proceeds from issuance of senior long-term debt					$ 18,800,000,000
Maximum interest increase								0.50%
Senior Notes \| Subsequent Event
Debt Instrument [Line Items]
Principal Issuances	3,000,000,000.0
Senior Notes \| Sprint
Debt Instrument [Line Items]
Principal Issuances													$ 3,900,000,000
Minimum \| Senior Notes
Debt Instrument [Line Items]
Term preceding maturity date								1 month
Maximum \| Senior Notes
Debt Instrument [Line Items]
Term preceding maturity date								6 months
5.300% Senior Notes due 2021 \| Affiliates
Debt Instrument [Line Items]
Interest rate, stated percentage								5.30%
5.300% Senior Notes due 2021 \| Senior Notes \| Affiliates
Debt Instrument [Line Items]
Interest rate, stated percentage								5.30%
Guaranteed Notes due 2028 \| Sprint
Debt Instrument [Line Items]
Interest rate, stated percentage						7.25%
Principal amount outstanding						$ 1,000,000,000.0
Senior Secured Term Loan Commitment
Debt Instrument [Line Items]
Principal Issuances		$ 5,000,000,000.0
Number of extension options \| option		1
Extension term		6 months
Senior Secured Term Loan Commitment \| Subsequent Event
Debt Instrument [Line Items]
Total outstanding obligation	2,000,000,000.0
Senior Secured Term Loan Commitment \| LIBOR
Debt Instrument [Line Items]
Variable rate		1.25%
Senior Secured Notes due 2025, 3.500%
Debt Instrument [Line Items]
Principal Issuances								$ 3,000,000,000
Interest rate, stated percentage					3.50%
Proceeds from issuance of senior long-term debt								2,988,000,000
Senior Secured Notes due 2050, 4.500%
Debt Instrument [Line Items]
Principal Issuances								3,000,000,000
Interest rate, stated percentage					4.50%
Proceeds from issuance of senior long-term debt								2,976,000,000
Senior Notes due 2026, 1.500%
Debt Instrument [Line Items]
Principal Issuances								1,000,000,000
Interest rate, stated percentage												1.50%
Proceeds from issuance of senior long-term debt								995,000,000
Senior Notes due 2031, 2.550%
Debt Instrument [Line Items]
Principal Issuances								1,750,000,000
Interest rate, stated percentage												2.55%
Proceeds from issuance of senior long-term debt								1,738,000,000
Senior Notes due 2028, 2.050%, Issued October 6, 2020
Debt Instrument [Line Items]
Principal Issuances								500,000,000
Interest rate, stated percentage				2.05%
Proceeds from issuance of senior long-term debt								511,000,000
3.300% Senior Secured Notes due 2051
Debt Instrument [Line Items]
Principal Issuances								1,500,000,000
Interest rate, stated percentage				3.30%
Proceeds from issuance of senior long-term debt								1,484,000,000
2.250% Senior Secured Notes due 2031
Debt Instrument [Line Items]
Principal Issuances								$ 1,000,000,000
Interest rate, stated percentage			2.25%					2.25%
Proceeds from issuance of senior long-term debt								$ 995,000,000
3.600% Senior Secured Notes due 2060
Debt Instrument [Line Items]
Principal Issuances								1,000,000,000
Interest rate, stated percentage			3.60%
Proceeds from issuance of senior long-term debt								989,000,000
2.250% Senior Notes due 2026 \| Subsequent Event
Debt Instrument [Line Items]
Principal Issuances	$ 1,000,000,000.0
Interest rate, stated percentage	2.25%
2.625% Senior Notes due 2029 \| Subsequent Event
Debt Instrument [Line Items]
Principal Issuances	$ 1,000,000,000.0
Interest rate, stated percentage	2.625%
2.875% Senior Notes due 2031 \| Subsequent Event
Debt Instrument [Line Items]
Principal Issuances	$ 1,000,000,000.0
Interest rate, stated percentage	2.875%
Sprint
Debt Instrument [Line Items]
Principal Issuances								24,605,000,000
Total outstanding obligation								4,600,000,000
Sprint \| Senior Notes
Debt Instrument [Line Items]
Payments for requisite consents to third-party note holders						95,000,000
Sprint \| DT
Debt Instrument [Line Items]
Payments of consent fees							$ 7,000,000
Sprint \| DT \| Senior Notes \| Affiliates
Debt Instrument [Line Items]
Indebtedness to affiliates						4,000,000,000.0
Sprint \| Secured Debt Financing
Debt Instrument [Line Items]
Financing commitment, amount						27,000,000,000.0
Proceeds from Lines of Credit						22,600,000,000
Sprint \| Secured Revolving Credit Facility
Debt Instrument [Line Items]
Financing commitment, amount						$ 4,000,000,000.0
Sprint \| Secured Revolving Credit Facility \| LIBOR \| Minimum
Debt Instrument [Line Items]
Variable rate						1.00%
Sprint \| Secured Revolving Credit Facility \| LIBOR \| Maximum
Debt Instrument [Line Items]
Variable rate						1.25%
Sprint \| Secured Term Loan Facility
Debt Instrument [Line Items]
Financing commitment, amount						$ 4,000,000,000.0
Net leverage ratio						0.75
Sprint \| Secured Term Loan Facility \| DT
Debt Instrument [Line Items]
Repayment of debt						$ 4,000,000,000.0
Sprint \| Secured Term Loan Facility \| LIBOR
Debt Instrument [Line Items]
Variable rate						3.00%
Sprint \| Secured Bridge Loan Facility
Debt Instrument [Line Items]
Financing commitment, amount					$ 19,000,000,000.0	$ 19,000,000,000.0
Sprint \| Secured Bridge Loan Facility \| LIBOR
Debt Instrument [Line Items]
Variable rate						1.25%
Sprint \| New Credit Agreement
Debt Instrument [Line Items]
Financial maintenance covenant						3.3
Sprint \| 5.300% Senior Notes due 2021 \| DT \| Senior Notes
Debt Instrument [Line Items]
Principal Issuances						$ 2,000,000,000.0
Interest rate, stated percentage						5.30%
Sprint \| 6.000% Senior Notes due 2024 \| DT \| Senior Notes
Debt Instrument [Line Items]
Principal Issuances						$ 2,000,000,000.0
Interest rate, stated percentage						6.00%
Sprint \| Secured Term Loan due 2024
Debt Instrument [Line Items]
Principal amount outstanding						$ 5,900,000,000
Sprint \| Accounts receivable facility
Debt Instrument [Line Items]
Principal Issuances								$ 0
Total amount outstanding						2,300,000,000
Sprint \| Secured and Unsecured Debt Financing
Debt Instrument [Line Items]
Payments of consent fees						355,000,000
Sprint \| Ratio Secured Debt Amendment \| Senior Notes
Debt Instrument [Line Items]
Payments for requisite consents to third-party note holders						54,000,000
Sprint \| Existing Sprint Spectrum Notes \| Senior Notes
Debt Instrument [Line Items]
Payments for requisite consents to third-party note holders						$ 41,000,000