T-Mobile US (TMUS) 10-K 8 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2017	Feb. 02, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	T-MOBILE US, INC.
Trading Symbol	TMUS
Entity Central Index Key	1,283,699
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		854,428,593
Entity Public Float			$ 17.8

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 1,219	$ 5,500
Accounts receivable, net of allowances of $86 and $102	1,915	1,896
Equipment installment plan receivables, net	2,290	1,930
Accounts receivable from affiliates	22	40
Inventories	1,566	1,111
Asset purchase deposit	0	2,203
Other current assets	1,903	1,537
Total current assets	8,915	14,217
Property and equipment, net	22,196	20,943
Goodwill	1,683	1,683
Spectrum licenses	35,366	27,014
Other intangible assets, net	217	376
Equipment installment plan receivables due after one year, net	1,274	984
Other assets	912	674
Total assets	70,563	65,891
Current liabilities
Accounts payable and accrued liabilities	8,528	7,152
Payables to affiliates	182	125
Short-term debt	1,612	354
Deferred revenue	779	986
Other current liabilities	414	405
Total current liabilities	11,515	9,022
Long-term debt	12,121	21,832
Long-term debt to affiliates	14,586	5,600
Tower obligations	2,590	2,621
Deferred tax liabilities	3,537	4,938
Deferred rent expense	2,720	2,616
Other long-term liabilities	935	1,026
Total long-term liabilities	36,489	38,633
Commitments and contingencies (Note 13)
Stockholders' equity
5.50% Mandatory Convertible Preferred Stock Series A, par value $0.00001 per share, 100,000,000 shares authorized; 0 and 20,000,000 shares issued; 0 and 20,000,000 shares outstanding; $0 and $1,000 aggregate liquidation value	0	0
Common Stock, par value $0.00001 per share, 1,000,000,000 shares authorized; 860,861,998 and 827,768,818 shares issued, 859,406,651 and 826,357,331 shares outstanding	0	0
Additional paid-in capital	38,629	38,846
Treasury stock, at cost, 1,455,347 and 1,411,487 shares issued	(4)	(1)
Accumulated other comprehensive income	8	1
Accumulated deficit	(16,074)	(20,610)
Total stockholders' equity	22,559	18,236
Total liabilities and stockholders' equity	$ 70,563	$ 65,891

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowances	$ 86,000,000	$ 102,000,000
Annual dividend rate	5.50%	5.50%
5.50% Mandatory convertible preferred stock series A, par value (in USD per share)	$ 0.00001	$ 0.00001
5.50% Mandatory convertible preferred stock series A, shares authorized (in shares)	100,000,000	100,000,000
5.50% Mandatory convertible preferred stock series A, shares issued (in shares)	0	20,000,000
5.50% Mandatory convertible preferred stock series A, shares outstanding (in shares)	0	20,000,000
5.50% Mandatory convertible preferred stock series A, aggregate liquidation value	$ 0	$ 1,000,000,000
Common stock, par value (in USD per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	860,861,998	827,768,818
Common stock, shares outstanding (in shares)	859,406,651	826,357,331
Treasury stock, at cost (in shares)	1,455,347	1,411,487

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues
Branded postpaid revenues	$ 19,448	$ 18,138	$ 16,383
Branded prepaid revenues	9,380	8,553	7,553
Wholesale revenues	1,102	903	692
Roaming and other service revenues	230	250	193
Total service revenues	30,160	27,844	24,821
Equipment revenues	9,375	8,727	6,718
Other revenues	1,069	919	928
Total revenues	40,604	37,490	32,467
Operating expenses
Cost of services, exclusive of depreciation and amortization shown separately below	6,100	5,731	5,554
Cost of equipment sales	11,608	10,819	9,344
Selling, general and administrative	12,259	11,378	10,189
Depreciation and amortization	5,984	6,243	4,688
Cost of MetroPCS business combination	0	104	376
Gains on disposal of spectrum licenses	(235)	(835)	(163)
Total operating expense	35,716	33,440	29,988
Operating income	4,888	4,050	2,479
Other income (expense)
Interest expense	(1,111)	(1,418)	(1,085)
Interest expense to affiliates	(560)	(312)	(411)
Interest income	17	13	6
Other expense, net	(73)	(6)	(11)
Total other expense, net	(1,727)	(1,723)	(1,501)
Income before income taxes	3,161	2,327	978
Income tax benefit (expense)	1,375	(867)	(245)
Net income	4,536	1,460	733
Dividends on preferred stock	(55)	(55)	(55)
Net income attributable to common stockholders	4,481	1,405	678
Net income	4,536	1,460	733
Other comprehensive income (loss), net of tax
Unrealized gain (loss) on available-for-sale securities, net of tax effect $2, $1 and $(1)	7	2	(2)
Other comprehensive income (loss)	7	2	(2)
Total comprehensive income	$ 4,543	$ 1,462	$ 731
Earnings per share
Basic (in USD per share)	$ 5.39	$ 1.71	$ 0.83
Diluted (in USD per share)	$ 5.20	$ 1.69	$ 0.82
Weighted average shares outstanding
Basic (in shares)	831,850,073	822,470,275	812,994,028
Diluted (in shares)	871,787,450	833,054,545	822,617,938

Consolidated Statements of Com5

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Unrealized gain on available-for-sale securities, tax	$ 2	$ 1	$ (1)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net income	$ 4,536	$ 1,460	$ 733
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	5,984	6,243	4,688
Stock-based compensation expense	306	235	201
Deferred income tax (benefit) expense	(1,404)	914	256
Bad debt expense	388	477	547
Losses from sales of receivables	299	228	204
Deferred rent expense	76	121	167
Gains on disposal of spectrum licenses	(235)	(835)	(163)
Change in fair value of embedded derivatives	(52)	(25)	148
Changes in operating assets and liabilities
Accounts receivable	(444)	(603)	(259)
Equipment installment plan receivables	(894)	97	1,089
Inventories	(844)	(802)	(2,495)
Deferred purchase price from sales of receivables	(86)	(270)	(185)
Other current and long-term assets	(575)	(133)	(217)
Accounts payable and accrued liabilities	1,079	(1,201)	693
Other current and long-term liabilities	(233)	158	22
Other, net	61	71	(15)
Net cash provided by operating activities	7,962	6,135	5,414
Investing activities
Purchases of property and equipment, including capitalized interest of $136, $142 and $246	(5,237)	(4,702)	(4,724)
Purchases of spectrum licenses and other intangible assets, including deposits	(5,828)	(3,968)	(1,935)
Purchases of short-term investments	0	0	(2,997)
Sales of short-term investments	0	2,998	0
Other, net	1	(8)	96
Net cash used in investing activities	(11,064)	(5,680)	(9,560)
Financing activities
Proceeds from issuance of long-term debt	10,480	997	3,979
Proceeds from tower obligations	0	0	140
Proceeds from borrowing on revolving credit facility	2,910	0	0
Repayments of revolving credit facility	(2,910)	0	0
Repayments of capital lease obligations	(486)	(205)	(57)
Repayments of short-term debt for purchases of inventory, property and equipment, net	(300)	(150)	(564)
Repayments of long-term debt	(10,230)	(20)	0
Proceeds from exercise of stock options	21	29	47
Repurchases of common shares	(427)	0	0
Tax withholdings on share-based awards	(166)	(121)	(156)
Dividends on preferred stock	(55)	(55)	(55)
Other, net	(16)	(12)	79
Net cash (used in) provided by financing activities	(1,179)	463	3,413
Change in cash and cash equivalents	(4,281)	918	(733)
Cash and cash equivalents
Beginning of period	5,500	4,582	5,315
End of period	1,219	5,500	4,582
Supplemental disclosure of cash flow information
Interest payments, net of amounts capitalized, $79, $0 and $0 of which recorded as debt discount (Note 7)	2,028	1,681	1,298
Income tax payments	31	25	54
Changes in accounts payable for purchases of property and equipment	313	285	46
Leased devices transferred from inventory to property and equipment	1,131	1,588	2,451
Returned leased devices transferred from property and equipment to inventory	(742)	(602)	(166)
Issuance of short-term debt for financing of property and equipment	292	150	500
Assets acquired under capital lease obligations	$ 887	$ 799	$ 470

Consolidated Statements of Cas7

Consolidated Statements of Cash Flows Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Cash Flows [Abstract]
Capitalized interest	$ (136)	$ (142)	$ (246)
Discount	$ 79	$ 0	$ 0

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Preferred Stock Outstanding	Common Stock Outstanding	Treasury Shares at Cost	Par Value and Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance, beginning of period at Dec. 31, 2014	$ 15,663			$ 0	$ 38,503	$ 1	$ (22,841)
Preferred stock, shares outstanding, beginning (in shares) at Dec. 31, 2014		20,000,000
Common stock, shares outstanding, beginning (in shares) at Dec. 31, 2014			807,468,603
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	733						733
Other comprehensive income (loss)	(2)					(2)
Stock-based compensation	227				227
Exercise of stock options (in shares)			2,381,650
Exercise of stock options	47				47
Stock issued for employee stock purchase plan (in shares)			761,085
Stock issued for employee stock purchase plan	21				21
Issuance of vested restricted stock units (in shares)			11,956,345
Shares withheld related to net share settlement of stock awards and stock options (in shares)			(4,176,464)
Shares withheld related to net share settlement of stock awards and stock options	(156)				(156)
Excess tax benefit from stock-based compensation	79				79
Dividends on preferred stock	(55)				(55)
Preferred stock, shares outstanding, ending (in shares) at Dec. 31, 2015		20,000,000
Common stock, shares outstanding, ending (in shares) at Dec. 31, 2015			818,391,219
Balance, end of period at Dec. 31, 2015	16,557			0	38,666	(1)	(22,108)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,460						1,460
Other comprehensive income (loss)	2					2
Stock-based compensation	264				264
Exercise of stock options (in shares)			982,904
Exercise of stock options	29				29
Stock issued for employee stock purchase plan (in shares)			1,905,534
Stock issued for employee stock purchase plan	63				63
Issuance of vested restricted stock units (in shares)			7,712,463
Shares withheld related to net share settlement of stock awards and stock options (in shares)			(2,605,807)
Shares withheld related to net share settlement of stock awards and stock options	(122)				(122)
Transfer RSU to NQDC plan (in shares)			(28,982)
Transfer RSU to NQDC plan	0			(1)	1
Dividends on preferred stock	(55)				(55)
Prior year Retained Earnings	$ 38						38
Preferred stock, shares outstanding, ending (in shares) at Dec. 31, 2016	20,000,000	20,000,000
Common stock, shares outstanding, ending (in shares) at Dec. 31, 2016	826,357,331		826,357,331
Balance, end of period at Dec. 31, 2016	$ 18,236			(1)	38,846	1	(20,610)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	4,536						4,536
Other comprehensive income (loss)	7					7
Stock-based compensation	344				344
Exercise of stock options (in shares)			450,493
Exercise of stock options	19				19
Stock issued for employee stock purchase plan (in shares)			1,832,043
Stock issued for employee stock purchase plan	82				82
Issuance of vested restricted stock units (in shares)			8,338,271
Shares withheld related to net share settlement of stock awards and stock options (in shares)			(2,754,721)
Shares withheld related to net share settlement of stock awards and stock options	$ (166)				(166)
Mandatory conversion of preferred shares to common shares (in shares)		(20,000,000)	32,237,983
Repurchases of common stock (in shares)	(7,010,889)		(7,010,889)
Repurchases of common stock	$ (444)				(444)
Transfer RSU to NQDC plan (in shares)			(43,860)
Transfer RSU to NQDC plan	0			(3)	3
Dividends on preferred stock	$ (55)				(55)
Preferred stock, shares outstanding, ending (in shares) at Dec. 31, 2017	0	0
Common stock, shares outstanding, ending (in shares) at Dec. 31, 2017	859,406,651		859,406,651
Balance, end of period at Dec. 31, 2017	$ 22,559			$ (4)	$ 38,629	$ 8	$ (16,074)

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Significant Accounting Policies	Note 1 – Summary of Significant Accounting Policies Description of Business T-Mobile US, Inc. (“T-Mobile,” “we,” “our,” “us” or the “Company”), together with its consolidated subsidiaries, is a leading provider of mobile communications services, including voice, messaging and data, under its flagship brands, T-Mobile and MetroPCS, in the United States (“U.S.”), Puerto Rico and the U.S. Virgin Islands. We provide mobile communications services primarily using 4G Long-Term Evolution (“LTE”) technology. We also offer a wide selection of wireless devices, including handsets, tablets and other mobile communication devices, and accessories for sale, as well as financing through Equipment Installment Plans (“EIP”) and leasing through JUMP! On Demand™. Additionally, we provide reinsurance for handset insurance policies and extended warranty contracts offered to our mobile communications customers. Basis of Presentation The consolidated financial statements include the balances and results of operations of T-Mobile and our consolidated subsidiaries. We operate as a single operating segment. We consolidate majority-owned subsidiaries over which we exercise control, as well as variable interest entities (“VIE”) where we are deemed to be the primary beneficiary and VIEs, which cannot be deconsolidated, such as those related to Tower obligations. Intercompany transactions and balances have been eliminated in consolidation. Certain prior year amounts have been reclassified, such as those relating to the imputed discount on EIP receivables reclassified from Interest income to Other revenues in our Consolidated Statements of Comprehensive Income , to conform to the current year’s presentation. See “Change in Accounting Principle” below. The preparation of financial statements in conformity with U.S. generally accepted accounting principles (“GAAP”) requires our management to make estimates and assumptions which affect the financial statements and accompanying notes. Examples include service revenues earned but not yet billed, service revenues billed but not yet earned, relative selling prices, allowances for credit losses and sales returns, discounts for imputed interest on EIP receivables, guarantee liabilities, losses incurred but not yet reported, tax liabilities, deferred income taxes including valuation allowances, useful lives of long-lived assets, cost estimates of asset retirement obligations, residual values on leased handsets, reasonably assured renewal terms for operating leases, stock-based compensation forfeiture rates, and fair value measurements, including those related to goodwill, spectrum licenses, intangible assets, beneficial interests in factoring and securitization transactions and derivative financial instruments. Estimates are based on historical experience, where applicable, and other assumptions which our management believes are reasonable under the circumstances. These estimates are inherently subject to judgment and actual results could differ from those estimates. Cash and Cash Equivalents Cash equivalents consist of highly liquid money market funds and U.S. Treasury securities with remaining maturities of three months or less at the date of purchase. Receivables and Allowance for Credit Losses Accounts receivable consist primarily of amounts currently due from customers, other carriers and third-party retail channels. Accounts receivable not held for sale are reported in the balance sheet at outstanding principal adjusted for any charge-offs and the allowance for credit losses. Accounts receivable held for sale are reported at the lower of amortized cost or fair value. We have an arrangement to sell the majority of service accounts receivable on a revolving basis, which are treated as sales of financial assets. We offer certain retail customers the option to pay for their devices and other purchases in installments over a period of up to 24 months using an EIP. EIP receivables not held for sale are reported in the balance sheet at outstanding principal adjusted for any charge-offs, allowance for credit losses and unamortized discounts. Receivables held for sale are reported at the lower of amortized cost or fair value. At the time of an installment sale, we impute a discount for interest as there is no stated rate of interest on the EIP receivables and record the EIP receivables at their present value, which is determined by discounting future payments at the imputed interest rate. The difference between the present value of the EIP receivables and their face amount results in a discount which is recorded as a direct reduction to the carrying value with a corresponding reduction to equipment revenues in our Consolidated Statements of Comprehensive Income . We determine the imputed discount rate based primarily on current market interest rates and the estimated credit risk on the EIP receivables. As a result, we do not recognize a separate valuation allowance at the time of issuance as the effects of uncertainty about future cash flows are included in the initial present value measurement of the receivable. The imputed discount on EIP receivables is amortized over the financed installment term using the effective interest method and recognized as Other revenues in our Consolidated Statements of Comprehensive Income . Subsequent to the initial determination of the imputed discount, we assess the need for and, if necessary, recognize an allowance for credit losses to the extent the amount of estimated probable losses on the gross EIP receivable balances exceed the remaining unamortized imputed discount balances. The current portion of the EIP receivables is included in Equipment installment plan receivables, net and the long-term portion of the EIP receivables is included in Equipment installment plan receivables due after one year, net in our Consolidated Balance Sheets . We have an arrangement to sell certain EIP receivables on a revolving basis, which are treated as sales of financial assets. We maintain an allowance for credit losses and determine its appropriateness through an established process that assesses the losses inherent in our receivables portfolio. We develop and document our allowance methodology at the portfolio segment level - accounts receivable portfolio and EIP receivable portfolio segments. While we attribute portions of the allowance to our respective accounts receivable and EIP portfolio segments, the entire allowance is available to absorb credit losses inherent in the total receivables portfolio. Our process involves procedures to appropriately consider the unique risk characteristics of our accounts receivable and EIP receivable portfolio segments. For each portfolio segment, losses are estimated collectively for groups of receivables with similar characteristics. Our allowance levels are influenced by receivable volumes, receivable delinquency status, historical loss experience and other conditions influencing loss expectations, such as macro-economic conditions. Inventories Inventories consist primarily of wireless devices and accessories, which are valued at the lower of cost or market. Cost is determined using standard cost which approximates average cost. Shipping and handling costs paid to wireless device and accessories vendors, and costs to refurbish used devices recovered through our device upgrade programs are included in the standard cost of inventory. We record inventory write-downs to net realizable value for obsolete and slow-moving items based on inventory turnover trends and historical experience. Long-Lived Assets Long-lived assets include assets that do not have indefinite lives, such as property and equipment and other intangible assets. We assess potential impairments to our long-lived assets when events or changes in circumstances indicate the carrying amount of the asset may not be recoverable. If any indicators of impairment are present, we test recoverability. The carrying value of a long-lived asset or asset group is not recoverable if it exceeds the sum of the undiscounted cash flows expected to be generated from the use and eventual disposition of the asset or asset group. If the undiscounted cash flows do not exceed the asset or asset group’s carrying amount, then an impairment loss is recorded, measured as the amount by which the carrying amount of a long-lived asset or asset group exceeds its fair value. Property and Equipment Property and equipment consists of buildings and equipment, wireless communication systems, leasehold improvements, capitalized software, leased wireless devices and construction in progress. Buildings and equipment include certain network server equipment. Wireless communication systems include assets to operate our wireless network and IT data centers, including tower assets and leasehold improvements, assets related to the liability for the retirement of long-lived assets and capital leases. Leasehold improvements include asset improvements other than those related to the wireless network. Property and equipment are recorded at cost less accumulated depreciation and impairments, if any, in Property and equipment, net on our Consolidated Balance Sheets . We generally depreciate property and equipment over the period the property and equipment provide economic benefit. Depreciable life studies are performed periodically to confirm the appropriateness of useful lives for certain categories of property and equipment. These studies take into account actual usage, physical wear and tear, replacement history and assumptions about technology evolution. When these factors indicate the useful life of an asset is different from the previous assessment, the remaining book value is depreciated prospectively over the adjusted remaining estimated useful life. Leasehold improvements are depreciated over the shorter of their estimated useful lives or the related lease term. We introduced JUMP! On Demand, which allows customers to lease a device over a period of up to 18 months and upgrade it for a new device up to one time per month. To date, all of our leased devices were classified as operating leases. At operating lease inception, leased wireless devices are transferred from inventory to property and equipment. Leased wireless devices are depreciated to their estimated residual value over the period expected to provide utility to us, which is generally shorter than the lease term and considers expected losses. Revenues associated with the leased wireless devices, net of incentives, are generally recognized over the lease term. Upon device upgrade or at lease end, customers must return or purchase their device. Returned devices transferred from Property and equipment, net are recorded as inventory and are valued at the lower of cost or market with any write-down to market recognized as Cost of equipment sales in our Consolidated Statements of Comprehensive Income . Costs of major replacements and improvements are capitalized. Repair and maintenance expenditures which do not enhance or extend the asset’s useful life are charged to operating expenses as incurred. Construction costs, labor and overhead incurred in the expansion or enhancement of our wireless network are capitalized. Capitalization commences with pre-construction period administrative and technical activities, which includes obtaining leases, zoning approvals and building permits, and ceases at the point at which the asset is ready for its intended use. We capitalize interest associated with the acquisition or construction of certain property and equipment. Capitalized interest is reported as a reduction in interest expense and depreciated over the useful life of the related assets. Future obligations related to capital leases are included in Short-term debt and Long-term debt in our Consolidated Balance Sheets . Depreciation of assets held under capital leases is included in Depreciation and amortization expense in our Consolidated Statements of Comprehensive Income . We record an asset retirement obligation for the fair value of legal obligations associated with the retirement of tangible long-lived assets and a corresponding increase in the carrying amount of the related asset in the period in which the obligation is incurred. In periods subsequent to initial measurement, we recognize changes in the liability resulting from the passage of time and revisions to either the timing or the amount of the original estimate. Over time, the liability is accreted to its present value and the capitalized cost is depreciated over the estimated useful life of the asset. Our obligations relate primarily to certain legal obligations to remediate leased property on which our network infrastructure and administrative assets are located. We capitalize certain costs incurred in connection with developing or acquiring internal use software. Capitalization of software costs commences once the final selection of the specific software solution has been made and management authorizes and commits to funding the software project. Capitalized software costs are included in Property and equipment, net in our Consolidated Balance Sheets and are amortized on a straight-line basis over the estimated useful life of the asset. Costs incurred during the preliminary project stage, as well as maintenance and training costs, are expensed as incurred. Other Intangible Assets Intangible assets that do not have indefinite useful lives are amortized over their estimated useful lives. Customer lists are amortized using the sum-of-the-years-digits method over the expected period in which the relationship is expected to contribute to future cash flows. The remaining finite-lived intangible assets are amortized using the straight-line method. Goodwill and Indefinite-Lived Intangible Assets Goodwill Goodwill consists of the excess of the purchase price over the fair value of identifiable net assets acquired in a business combination. Spectrum Licenses Spectrum licenses are carried at costs incurred to acquire the spectrum licenses and the costs to prepare the spectrum licenses for their intended use, such as costs to clear acquired spectrum licenses. The Federal Communications Commission (“FCC”) issues spectrum licenses which provide us with the exclusive right to utilize designated radio frequency spectrum within specific geographic service areas to provide wireless communication services. While spectrum licenses are issued for a fixed period of time, typically for up to fifteen years, the FCC has granted license renewals routinely and at a nominal cost. The spectrum licenses held by us expire at various dates. We believe we will be able to meet all requirements necessary to secure renewal of our spectrum licenses at nominal costs. Moreover, we determined there are currently no legal, regulatory, contractual, competitive, economic or other factors that limit the useful lives of our spectrum licenses. Therefore, we determined the spectrum licenses should be treated as indefinite-lived intangible assets. At times, we enter into agreements to sell or exchange spectrum licenses. Upon entering into the arrangement, if the transaction has been deemed to have commercial substance, spectrum licenses are reviewed for impairment and transferred at their carrying value, net of any impairment, to assets held for sale included in Other current assets in our Consolidated Balance Sheets until approval and completion of the exchange or sale. Upon closing of the transaction, spectrum licenses acquired as part of an exchange of nonmonetary assets are valued at fair value and the difference between the fair value of the spectrum licenses obtained, book value of the spectrum licenses transferred and cash paid, if any, is recognized as a gain and included in Gains on disposal of spectrum licenses in our Consolidated Statements of Comprehensive Income . Our fair value estimates of spectrum licenses are based on information for which there is little or no observable market data. If the transaction lacks commercial substance or the fair value is not measurable, the acquired spectrum licenses are recorded at the book value of the assets transferred or exchanged. Impairment We assess the carrying value of our goodwill and other indefinite-lived intangible assets, such as our spectrum licenses, for potential impairment annually as of December 31, or more frequently if events or changes in circumstances indicate such assets might be impaired. When assessing goodwill for impairment we may elect to first perform a qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. If we do not perform a qualitative assessment, or if the qualitative assessment indicates it is more likely than not the fair value of the single reporting unit is less than its carrying amount, we perform a quantitative test. We recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized would not exceed the total amount of goodwill allocated to that reporting unit. We test our spectrum licenses for impairment on an aggregate basis, consistent with our management of the overall business at a national level. We may elect to first perform a qualitative assessment to determine whether it is more likely than not that the fair value of an intangible asset is less than its carrying value. If we do not perform the qualitative assessment, or if the qualitative assessment indicates it is more likely than not the fair value of the intangible asset is less than its carrying amount, we calculate the estimated fair value of the intangible asset. If the estimated fair value of the spectrum licenses is lower than their carrying amount, an impairment loss is recognized for the difference. We estimate fair value using the Greenfield methodology, which is an income approach, to estimate the price at which an orderly transaction to sell the asset would take place between market participants at the measurement date under current market conditions. Guarantee Liabilities We offer a device trade-in program, Just Upgrade My Phone (“JUMP!”), which provides eligible customers a specified-price trade-in right to upgrade their device. Upon enrollment, participating customers must finance the purchase of a device on an EIP and have a qualifying T-Mobile monthly wireless service plan, which is treated as a single multiple-element arrangement when entered into at or near the same time. Upon a qualifying JUMP! program upgrade, the customer’s remaining EIP balance is settled provided they trade-in their eligible used device in good working condition and purchase a new device from us on a new EIP. For customers who enroll in JUMP!, we recognize a liability and reduce revenue for the portion of revenue which represents the estimated fair value of the specified-price trade-in right guarantee. The guarantee liability is valued based on various economic and customer behavioral assumptions, which requires judgment, including estimating the customer's remaining EIP balance at trade-in, the expected fair value of the used device at trade-in, and the probability and timing of trade-in. We assess our guarantee liability at each reporting date to determine if facts and circumstances would indicate the incurrence of an incremental contingent liability is probable and if so, reasonably estimable. The recognition and subsequent adjustments of the contingent guarantee liability as a result of these assessments are recorded as adjustments to revenue. When customers upgrade their device, the difference between the EIP balance credit to the customer and the fair value of the returned device is recorded against the guarantee liabilities. Fair Value Measurements We carry certain assets and liabilities at fair value. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The three-tier hierarchy for inputs used in measuring fair value, which prioritizes the inputs based on the observability as of the measurement date, is as follows: Level 1 Quoted prices in active markets for identical assets or liabilities; Level 2 Observable inputs other than the quoted prices in active markets for identical assets and liabilities; and Level 3 Unobservable inputs for which there is little or no market data, which require us to develop assumptions of what market participants would use in pricing the asset or liability. Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement requires judgment, and may affect the placement of assets and liabilities being measured within the fair value hierarchy. The carrying values of cash and cash equivalents, short-term investments, accounts receivable, accounts receivable from affiliates and accounts payable approximate fair value due to the short-term maturities of these instruments. The carrying values of EIP receivables approximate fair value as the receivables are recorded at their present value, net of unamortized discount and allowance for credit losses. There were no financial instruments with a carrying value materially different from their fair value, based on quoted market prices or rates for the same or similar instruments, or internal valuation models. Derivative Financial Instruments Derivative financial instruments primarily relate to embedded derivatives for certain components of the reset feature of the Senior Reset Notes to affiliates, which are required to be bifurcated and are recorded on the Consolidated Balance Sheets at fair value. Changes in fair value are recognized in Interest expense to affiliates in our Consolidated Statements of Comprehensive Income . We do not enter into derivative positions for trading or speculative purposes. Revenue Recognition We primarily generate our revenue from providing wireless services to customers and selling or leasing devices and accessories. We offer our wireless services and devices to customers, which may be comprised of multiple contracts entered into with a customer at or near the same time. In recognizing revenue, we assess such agreements as a single bundled arrangement that may involve multiple deliverables, which include wireless services, wireless devices or a combination thereof, and allocate revenue between each deliverable based on the relative selling prices of each deliverable on a standalone basis. Wireless Services Revenue We generate our wireless service revenues from providing access to, and usage of, our wireless communications network. Service revenues also include revenues earned for providing value added services to customers, such as handset insurance services. Service revenues are billed either in advance or arrears or are prepaid and are recognized when the service is rendered and all other revenue recognition criteria have been met. Revenues that are not reasonably assured to be collectible are recorded on a cash basis as payments are received. The recognition of prepaid revenue is deferred until services are rendered or the customer’s rights to service expire unused. Generally, incentives given to customers are recorded as a reduction to revenue. We recognize service revenues for Data Stash plans when such services are delivered and the data is consumed, or at time of forfeiture or expiration. Revenues relating to unused data that is carried over to the following month are deferred and valued based on their relative standalone selling price. Revenue is recorded gross for arrangements involving the resale of third-party services where we are considered the primary obligor and is recorded net of associated costs incurred for services whereby we are not considered the primary obligor. Federal Universal Service Fund (“USF”) and other fees are assessed by various governmental authorities in connection with the services we provide to our customers. When we separately bill and collect these regulatory fees from customers, they are recorded gross in Total service revenues and cost of services in our Consolidated Statements of Comprehensive Income . For the years ended December 31, 2017 , 2016 and 2015 , we recorded approximately $258 million , $409 million and $334 million , respectively, of USF fees on a gross basis. Equipment Revenues We generate equipment revenues from the sale or lease of mobile communication devices and accessories. Device and accessory sales revenues are generally recognized when the products are delivered to, and accepted by, the customer or dealer. We defer a portion of equipment revenues and cost of equipment sales for expected device returns based on historical experience. We offer certain customers the option to pay for devices and accessories in installments using an EIP. Equipment sales not reasonably assured to be collectible are recorded on a cash basis as payments are received. In addition, for customers enrolled in JUMP!, we separate the JUMP! trade-in right from the multiple element arrangement at its fair value and defer the portion of revenue which represents the fair value of the trade-in right. See Guarantee Liabilities section above for further information. We introduced JUMP! On Demand, which allows customers to lease a device and upgrade their leased wireless device for a new device up to one time per month. Leased wireless devices are accounted for as operating leases and lease revenues are recognized as earned on a straight-line basis over the lease term. The residual value of purchased leased devices is recorded as equipment revenues and cost of equipment sales. See Property and Equipment section above for further information. Rent Expense We have operating leases for cell sites, retail locations, corporate offices and dedicated transportation lines, some of which have escalating rentals during the initial lease term and during subsequent optional renewal periods. We recognize rent expense on a straight-line basis, over the non-cancelable lease term and renewal periods that are considered reasonably assured at the inception of the lease. We consider several factors in assessing whether renewal periods are reasonably assured of being exercised, including the continued maturation of our network nationwide, technological advances within the telecommunications industry and the availability of alternative sites. Advertising Expense We expense the cost of advertising and other promotional expenditures to market our services and products as incurred. For the years ended December 31, 2017 , 2016 and 2015 , advertising expenses included in Selling, general and administrative expenses in our Consolidated Statements of Comprehensive Income were $1.8 billion , $1.7 billion and $1.6 billion , respectively. Income Taxes Deferred tax assets and liabilities are recognized based on temporary differences between the financial statement and tax bases of assets and liabilities using enacted tax rates expected to be in effect when these differences are realized. A valuation allowance is recorded when it is more likely than not that some portion or all of a deferred tax asset will not be realized. The ultimate realization of a deferred tax asset depends on the ability to generate sufficient taxable income of the appropriate character and in the appropriate taxing jurisdictions within the carryforward periods available. We account for uncertainty in income taxes recognized in the financial statements in accordance with the accounting guidance for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. We assess whether it is more likely than not that a tax position will be sustained upon examination based on the technical merits of the position and adjust the unrecognized tax benefits in light of changes in facts and circumstances, such as changes in tax law, interactions with taxing authorities and developments in case law. Other Comprehensive Income (Loss) Other comprehensive income (loss) consists of adjustments, net of tax, related to unrealized gains (losses) on available-for-sale securities. This is reported in Accumulated other comprehensive income as a separate component of stockholders’ equity until realized in earnings. Stock-Based Compensation Stock-based compensation cost for stock awards, which include restricted stock units (“RSUs”) and performance-based restricted stock units (“PRSUs”), is measured at fair value on the grant date and recognized as expense, net of expected forfeitures, over the related service period. The fair value of stock awards is based on the closing price of our common stock on the date of grant. RSUs are recognized as expense using the straight-line method. PRSUs are recognized as expense following a graded vesting schedule. Earnings Per Share Basic earnings per share is computed by dividing Net income attributable to common stockholders by the weighted-average number of common shares outstanding for the period. Diluted earnings per share is computed by giving effect to all potentially dilutive common shares outstanding during the period. Potentially dilutive common shares consist of outstanding stock options, RSUs and PRSUs, calculated using the treasury stock method, and prior to the conversion of our preferred stock, potentially dilutive common shares included mandatory convertible preferred stock calculated using the if-converted method. See Note 12 - Earnings Per Share for further information. Our Board of Directors authorized a share repurchase program during the fourth quarter of 2017. Repurchased shares are retired and reduce the number of shares issued and outstanding. See Note 10 - Repurchases of Common Stock for further information. Variable Interest Entities VIEs are entities which lack sufficient equity to permit the entity to finance its activities without additional subordinated financial support from other parties, have equity investors which do not have the ability to make significant decisions relating to the entity's operations through voting rights, do not have the obligation to absorb the expected losses or do not have the right to receive the residual returns of the entity. The most common type of VIE is a special purpose entity (“SPE”). SPEs are commonly used in securitization transactions in order to isolate certain assets and distribute the cash flows from those assets to investors. SPEs are generally structured to insulate investors from claims on the SPE's assets by creditors of other entities, including the creditors of the seller of the assets. The primary beneficiary is required to consolidate the assets and liabilities of the VIE. The primary beneficiary is the party which has both the power to direct the activities of an entity that most significantly impact the VIE's economic performance, and through its interests in the VIE, the obligation to absorb losses or the right to receive benefits from the VIE which could potentially be significant to the VIE. We consolidate VIEs when we are deemed to be the primary beneficiary or when the VIE cannot be deconsolidated. In assessing which party is the primary beneficiary, all the facts and circumstances are considered, including each party’s role in establishing the VIE and its ongoing rights and responsibilities. This assessment includes, first, identifying the activities that most significantly impact the VIE’s economic performance; and second, identifying which party, if any, has power over those activities. In general, the parties that make the most significant decisions affecting the VIE (such as asset managers and servicers) or have the right to unilaterally remove those decision-makers are deemed to have the power to direct the activities of a VIE. Change in Accounting Principle Effective January 1, 2017, the imputed discount on EIP receivables, which is amortized over the financed installment term using the effective interest method, and was previously presented within Interest income in our Consolidated Statements of Comprehensive Income , is now presented within Other revenues in our Consolidated Statements of Comprehensive Income . We believe this presentation is preferable because it provides a better representation of amounts earned from our major ongoing operations and aligns with industry practice thereby enhancing comparability. We have applied this change retrospectively and prese

Receivables and Allowance for C

Receivables and Allowance for Credit Losses	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Receivables and Allowance for Credit Losses	Note 2 – Receivables and Allowance for Credit Losses Our portfolio of receivables is comprised of two portfolio segments, accounts receivable and EIP receivables. Our accounts receivable segment primarily consists of amounts currently due from customers, including service and leased device receivables, other carriers and third-party retail channels. Based upon customer credit profiles, we classify the EIP receivable segment into two customer classes of “Prime” and “Subprime.” Prime customer receivables are those with lower delinquency risk and Subprime customer receivables are those with higher delinquency risk. Subprime customers may be required to make a down payment on their equipment purchases. In addition, certain customers within the Subprime category are required to pay an advance deposit. To determine a customer’s credit profile, we use a proprietary credit scoring model that measures the credit quality of a customer at the time of application for wireless communications service using several factors, such as credit bureau information, consumer credit risk scores and service plan characteristics. The following table summarizes the EIP receivables, including imputed discounts and related allowance for credit losses: (in millions) December 31, December 31, EIP receivables, gross $ 3,960 $ 3,230 Unamortized imputed discount (264 ) (195 ) EIP receivables, net of unamortized imputed discount 3,696 3,035 Allowance for credit losses (132 ) (121 ) EIP receivables, net $ 3,564 $ 2,914 Classified on the balance sheet as: Equipment installment plan receivables, net $ 2,290 $ 1,930 Equipment installment plan receivables due after one year, net 1,274 984 EIP receivables, net $ 3,564 $ 2,914 To determine the appropriate level of the allowance for credit losses, we consider a number of credit quality indicators, including historical credit losses and timely payment experience as well as current collection trends such as write-off frequency and severity, aging of the receivable portfolio, credit quality of the customer base and other qualitative factors such as macro-economic conditions. We write off account balances if collection efforts are unsuccessful and the receivable balance is deemed uncollectible, based on customer credit quality and the aging of the receivable. For EIP receivables, subsequent to the initial determination of the imputed discount, we assess the need for and, if necessary, recognize an allowance for credit losses to the extent the amount of estimated probable losses on the gross EIP receivable balances exceed the remaining unamortized imputed discount balances. The EIP receivables had weighted average effective imputed interest rates of 9.6% and 9.0% as of December 31, 2017 and 2016 , respectively. Activity for the years ended December 31, 2017 , 2016 , and 2015 , in the allowance for credit losses and unamortized imputed discount balances for the accounts receivable and EIP receivable segments were as follows: December 31, 2017 December 31, 2016 December 31, 2015 (in millions) Accounts Receivable Allowance EIP Receivables Allowance Total Accounts Receivable Allowance EIP Receivables Allowance Total Accounts Receivable Allowance EIP Receivables Allowance Total Allowance for credit losses and imputed discount, beginning of period $ 102 $ 316 $ 418 $ 116 $ 333 $ 449 $ 83 $ 448 $ 531 Bad debt expense 104 284 388 227 250 477 182 365 547 Write-offs, net of recoveries (120 ) (273 ) (393 ) (241 ) (277 ) (518 ) (149 ) (333 ) (482 ) Change in imputed discount on short-term and long-term EIP receivables N/A 252 252 N/A 186 186 N/A (84 ) (84 ) Impact on the imputed discount from sales of EIP receivables N/A (183 ) (183 ) N/A (176 ) (176 ) N/A (63 ) (63 ) Allowance for credit losses and imputed discount, end of period $ 86 $ 396 $ 482 $ 102 $ 316 $ 418 $ 116 $ 333 $ 449 Management considers the aging of receivables to be an important credit indicator. The following table provides delinquency status for the EIP portfolio segment on a gross basis, which we actively monitor as part of our current credit risk management practices and policies: December 31, 2017 December 31, 2016 (in millions) Prime Subprime Total EIP Receivables, gross Prime Subprime Total EIP Receivables, gross Current - 30 days past due $ 1,727 $ 2,133 $ 3,860 $ 1,375 $ 1,735 $ 3,110 31 - 60 days past due 17 29 46 27 38 65 61 - 90 days past due 6 16 22 7 16 23 More than 90 days past due 8 24 32 10 22 32 Total receivables, gross $ 1,758 $ 2,202 $ 3,960 $ 1,419 $ 1,811 $ 3,230

Sales of Certain Receivables

Sales of Certain Receivables	12 Months Ended
	Dec. 31, 2017
Transfers and Servicing [Abstract]
Sales of Certain Receivables	Note 3 – Sales of Certain Receivables We have entered into transactions to sell certain service and EIP accounts receivables. The transactions, including our continuing involvement with the sold receivables and the respective impacts to our consolidated financial statements, are described below. Sales of Service Receivables Overview of the Transaction In 2014, we entered into an arrangement to sell certain service accounts receivables on a revolving basis and in November 2016, the arrangement was amended to increase the maximum funding commitment to $950 million (the “service receivable sale arrangement”) and extend the scheduled expiration date to March 2018. In February 2018, the service receivable sale arrangement was again amended to extend the scheduled expiration date to March 2019. As of December 31, 2017 and 2016 , the service receivable sale arrangement provided funding of $880 million and $907 million , respectively. Sales of receivables occur daily and are settled on a monthly basis. The receivables consist of service charges currently due from customers and are short-term in nature. In connection with the service receivable sale arrangement, we formed a wholly-owned subsidiary, which qualifies as a bankruptcy remote entity, to sell service accounts receivables (the “Service BRE”). The Service BRE does not qualify as a VIE, and due to the significant level of control we exercise over the entity, it is consolidated. Pursuant to the arrangement, certain of our wholly-owned subsidiaries transfer selected receivables to the Service BRE. The Service BRE then sells the receivables to an unaffiliated entity (the “Service VIE”), which was established to facilitate the sale of beneficial ownership interests in the receivables to certain third parties. Variable Interest Entity We determined that the Service VIE qualifies as a VIE as it lacks sufficient equity to finance its activities. We have a variable interest in the Service VIE, but are not the primary beneficiary as we lack the power to direct the activities that most significantly impact the Service VIE’s economic performance. Those activities include committing the Service VIE to legal agreements to purchase or sell assets, selecting which receivables are purchased in the service receivable sale arrangement, determining whether the Service VIE will sell interests in the purchased service receivables to other parties, funding of the entity and servicing of receivables. We do not hold the power to direct the key decisions underlying these activities. For example, while we act as the servicer of the sold receivables, which is considered a significant activity of the Service VIE, we are acting as an agent in our capacity as the servicer and the counterparty to the service receivable sale arrangement has the ability to remove us as the servicing agent of the receivables at will with no recourse available to us. As we have determined we are not the primary beneficiary, the balances and results of the Service VIE are not included in our consolidated financial statements . The following table summarizes the carrying amounts and classification of assets, which consists primarily of the deferred purchase price and liabilities included in our Consolidated Balance Sheets that relate to our variable interest in the Service VIE: (in millions) December 31, December 31, Other current assets $ 236 $ 207 Accounts payable and accrued liabilities 25 17 Other current liabilities 180 129 Sales of EIP Receivables Overview of the Transaction In 2015, we entered into an arrangement to sell certain EIP accounts receivables on a revolving basis and in August 2017, the EIP sale arrangement was amended to reduce the maximum funding commitment to $1.2 billion (the “EIP sale arrangement”) and extend the scheduled expiration date to November 2018. In December 2017, the EIP sale arrangement was again amended to increase the maximum funding commitment to $1.3 billion . As of December 31, 2017 and 2016 , the EIP sale arrangement provided funding of $1.3 billion and $1.2 billion , respectively. Sales of EIP receivables occur daily and are settled on a monthly basis. The receivables consist of customer EIP balances, which require monthly customer payments for up to 24 months. In connection with this EIP sale arrangement, we formed a wholly-owned subsidiary, which qualifies as a bankruptcy remote entity (the “EIP BRE”). Pursuant to the EIP sale arrangement, our wholly-owned subsidiary transfers selected receivables to the EIP BRE. The EIP BRE then sells the receivables to a non-consolidated and unaffiliated third-party entity for which we do not exercise any level of control, nor does the entity qualify as a VIE. Variable Interest Entity We determined that the EIP BRE is a VIE as its equity investment at risk lacks the obligation to absorb a certain portion of its expected losses. We have a variable interest in the EIP BRE and determined that we are the primary beneficiary based on our ability to direct the activities which most significantly impact the EIP BRE’s economic performance. Those activities include selecting which receivables are transferred into the EIP BRE and sold in the EIP sale arrangement and funding of the EIP BRE. Additionally, our equity interest in the EIP BRE obligates us to absorb losses and gives us the right to receive benefits from the EIP BRE that could potentially be significant to the EIP BRE. Accordingly, we determined that we are the primary beneficiary, and include the balances and results of operations of the EIP BRE in our consolidated financial statements . The following table summarizes the carrying amounts and classification of assets, which consists primarily of the deferred purchase price and liabilities included in our Consolidated Balance Sheets that relate to the EIP BRE: (in millions) December 31, December 31, Other current assets $ 403 $ 371 Other assets 109 83 Other long-term liabilities 3 4 In addition, the EIP BRE is a separate legal entity with its own separate creditors who will be entitled, prior to any liquidation of the EIP BRE, to be satisfied prior to any value in the EIP BRE becoming available to us. Accordingly, the assets of the EIP BRE may not be used to settle our general obligations and creditors of the EIP BRE have limited recourse to our general credit. Sales of Receivables The transfers of service receivables and EIP receivables to the non-consolidated entities are accounted for as sales of financial assets. Once identified for sale, the receivable is recorded at the lower of cost or fair value. Upon sale, we derecognize the net carrying amount of the receivables. We recognize the net cash proceeds in Net cash provided by operating activities in our Consolidated Statements of Cash Flows . The proceeds are net of the deferred purchase price, consisting of a receivable from the purchasers that entitles us to certain collections on the receivables. We recognize the collection of the deferred purchase price in Net cash provided by operating activities as it is dependent on collection of the customer receivables and is not subject to significant interest rate risk. The deferred purchase price represents a financial asset that is primarily tied to the creditworthiness of the customers and which can be settled in such a way that we may not recover substantially all of our recorded investment, due to default by the customers on the underlying receivables. We elected, at inception, to measure the deferred purchase price at fair value with changes in fair value included in Selling, general and administrative expense in our Consolidated Statements of Comprehensive Income . The fair value of the deferred purchase price is determined based on a discounted cash flow model which uses primarily unobservable inputs (Level 3 inputs), including customer default rates. As of December 31, 2017 and 2016 , our deferred purchase price related to the sales of service receivables and EIP receivables was $745 million and $659 million , respectively. The following table summarizes the impacts of the sale of certain service receivables and EIP receivables in our Consolidated Balance Sheets : (in millions) December 31, December 31, Derecognized net service receivables and EIP receivables $ 2,725 $ 2,502 Other current assets 639 578 of which, deferred purchase price 636 576 Other long-term assets 109 83 of which, deferred purchase price 109 83 Accounts payable and accrued liabilities 25 17 Other current liabilities 180 129 Other long-term liabilities 3 4 Net cash proceeds since inception 2,058 2,030 Of which: Change in net cash proceeds during the year-to-date period 28 536 Net cash proceeds funded by reinvested collections 2,030 1,494 We recognized losses from sales of receivables of $299 million , $228 million and $204 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. These losses from sales of receivables were recognized in Selling, general and administrative expense in our Consolidated Statements of Comprehensive Income . Losses from sales of receivables include adjustments to the receivables’ fair values and changes in fair value of the deferred purchase price. Continuing Involvement Pursuant to the sale arrangements described above, we have continuing involvement with the service receivables and EIP receivables we sell as we service the receivables and are required to repurchase certain receivables, including ineligible receivables, aged receivables and receivables where write-off is imminent. We continue to service the customers and their related receivables, including facilitating customer payment collection, in exchange for a monthly servicing fee. As the receivables are sold on a revolving basis, the customer payment collections on sold receivables may be reinvested in new receivable sales. While servicing the receivables, we apply the same policies and procedures to the sold receivables as we apply to our owned receivables, and we continue to maintain normal relationships with our customers. Pursuant to the EIP sale arrangement, under certain circumstances, we are required to deposit cash or replacement EIP receivables primarily for contracts terminated by customers under our JUMP! Program. In addition, we have continuing involvement with the sold receivables as we may be responsible for absorbing additional credit losses pursuant to the sale arrangements. Our maximum exposure to loss related to the involvement with the service receivables and EIP receivables sold under the sale arrangements was $1.3 billion as of December 31, 2017 . The maximum exposure to loss, which is a required disclosure under GAAP, represents an estimated loss that would be incurred under severe, hypothetical circumstances whereby we would not receive the deferred purchase price portion of the contractual proceeds withheld by the purchasers and would also be required to repurchase the maximum amount of receivables pursuant to the sale arrangements without consideration for any recovery. As we believe the probability of these circumstances occurring is remote, the maximum exposure to loss is not an indication of our expected loss.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment	Note 4 – Property and Equipment The components of property and equipment were as follows: (in millions) Useful Lives December 31, December 31, Buildings and equipment Up to 40 years $ 2,066 $ 1,657 Wireless communications systems Up to 20 years 32,706 29,272 Leasehold improvements Up to 12 years 1,182 1,068 Capitalized software Up to 10 years 10,563 8,488 Leased wireless devices Up to 18 months 1,209 2,624 Construction in progress 1,771 2,613 Accumulated depreciation and amortization (27,301 ) (24,779 ) Property and equipment, net $ 22,196 $ 20,943 Wireless communication systems include capital lease agreements for network equipment with varying expiration terms through 2031 . Capital lease assets and accumulated amortization were $2.4 billion and $533 million , and $1.6 billion and $300 million , as of December 31, 2017 and 2016 , respectively. We capitalize interest associated with the acquisition or construction of certain property and equipment and spectrum intangible assets. We recognized capitalized interest of $136 million , $142 million and $230 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The components of leased wireless devices under our JUMP! On Demand program were as follows: (in millions) December 31, December 31, Leased wireless devices, gross $ 1,209 $ 2,624 Accumulated depreciation (417 ) (1,193 ) Leased wireless devices, net $ 792 $ 1,431 Future minimum payments expected to be received over the lease term related to the leased wireless devices, which exclude optional residual buy-out amounts at the end of the lease term, are summarized below: (in millions) Total Year Ended December 31, 2018 $ 485 2019 104 Total $ 589 Total depreciation expense relating to property and equipment was $5.8 billion , $6.0 billion and $4.4 billion for the years ended December 31, 2017 , 2016 and 2015 , respectively. Included in the total depreciation expense for the years ended December 31, 2017 , 2016 and 2015 was $1.0 billion , $1.5 billion and $312 million , respectively, related to leased wireless devices. For the years ended December 31, 2017 , 2016 and 2015 , we recorded additional depreciation expense of $63 million , $101 million and $85 million , respectively, as a result of adjustments to useful lives of network equipment expected to be replaced in connection with our network transformation and decommissioning the MetroPCS CDMA network and redundant network cell sites. Asset retirement obligations are primarily for certain legal obligations to remediate leased property on which our network infrastructure and administrative assets are located. Activity in our asset retirement obligations was as follows: (in millions) December 31, December 31, Asset retirement obligations, beginning of year $ 539 $ 483 Liabilities incurred 25 50 Liabilities settled (16 ) (67 ) Accretion expense 27 24 Changes in estimated cash flows (13 ) 49 Asset retirement obligations, end of year $ 562 $ 539 Classified on the balance sheet as: Other current liabilities $ 3 $ 16 Other long-term liabilities 559 523 Asset retirement obligations $ 562 $ 539 The corresponding assets, net of accumulated depreciation, related to asset retirement obligations were $220 million and $258 million as of December 31, 2017 and 2016 , respectively.

Goodwill, Spectrum Licenses and

Goodwill, Spectrum Licenses and Other Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Spectrum Licenses and Other Intangible Assets	Note 5 – Goodwill, Spectrum Licenses and Other Intangible Assets Goodwill There were no changes in carrying values of goodwill for the years ended December 31, 2017 and 2016 . Spectrum Licenses The following table summarizes our spectrum license activity for the years ended December 31, 2017 and 2016 : (in millions) December 31, 2017 December 31, 2016 Spectrum licenses, beginning of year $ 27,014 $ 23,955 Spectrum license acquisitions 8,599 3,334 Spectrum licenses transferred to held for sale (271 ) (324 ) Costs to clear spectrum 24 49 Spectrum licenses, end of year $ 35,366 $ 27,014 We had the following spectrum license transactions during 2017 : • In March 2017, we closed on an agreement with a third party for the exchange of certain AWS and PCS spectrum licenses. Upon closing of the transaction, we recorded the spectrum licenses received at their estimated fair value of approximately $123 million and recognized a gain of $37 million included in Gains on disposal of spectrum licenses in our Consolidated Statements of Comprehensive Income . • In April 2017, the FCC announced that we were the winning bidder of 1,525 licenses in the 600 MHz spectrum auction for an aggregate price of $8.0 billion . At inception of the auction in June 2016, we deposited $2.2 billion with the FCC which, based on the outcome of the auction, was sufficient to cover our down payment obligation due in April 2017. In May 2017, we paid the FCC the remaining $5.8 billion of the purchase price using cash reserves and by issuing debt to Deutsche Telekom AG (“DT”), our majority stockholder, pursuant to existing purchase commitments. See Note 7 - Debt for further information. The licenses are included in Spectrum licenses as of December 31, 2017 , in our Consolidated Balance Sheets . We began deployment of these licenses on our network in the third quarter of 2017 . • In September 2017, we closed on an agreement with a third party for the exchange of certain AWS and PCS spectrum licenses. Upon closing of the transaction, we recorded the spectrum licenses received at their estimated fair value of approximately $115 million and recognized a gain of $29 million included in Gains on disposal of spectrum licenses in our Consolidated Statements of Comprehensive Income . • In September 2017, we entered into a Unit Purchase Agreement (“UPA”) to acquire the remaining equity in Iowa Wireless Services, LLC (“IWS”), a 54% owned unconsolidated subsidiary, for a purchase price of $25 million . On January 1, 2018, we closed on the purchase agreement and received the IWS spectrum licenses, among other assets. As of December 31, 2017, we accounted for our existing investment in IWS under the equity method as we had significant influence, but not control. • In December 2017, we closed on an agreement with a third party for the exchange of certain AWS and PCS spectrum licenses. Upon closing of the transaction, we recorded the spectrum licenses received at their estimated fair value of approximately $352 million and recognized a gain of $168 million included in Gains on disposal of spectrum licenses in our Consolidated Statements of Comprehensive Income . We had the following spectrum license transactions during 2016 : • We closed on an agreement with AT&T Inc. for the acquisition and exchange of certain spectrum licenses. Upon closing of the transaction during the first quarter of 2016 , we recorded the spectrum licenses received at their estimated fair value of approximately $1.2 billion and recognized a gain of $636 million included in Gains on disposal of spectrum licenses in our Consolidated Statements of Comprehensive Income . • We closed on agreements with multiple third parties for the purchase and exchange of certain spectrum licenses for $1.3 billion in cash. Upon closing of the transactions, we recorded spectrum licenses received at their estimated fair values totaling approximately $1.7 billion and recognized gains of $199 million included in Gains on disposal of spectrum licenses in our Consolidated Statements of Comprehensive Income . • We closed on an agreement with a third party for the purchase of certain spectrum licenses covering approximately 11 million people for approximately $420 million during the fourth quarter of 2016 . Goodwill and Other Intangible Assets Impairment Assessments Our impairment assessment of goodwill and indefinite-lived intangible assets (spectrum licenses) resulted in no impairment as of December 31, 2017 and 2016 . Other Intangible Assets The components of Other intangible assets were as follows: Useful Lives December 31, 2017 December 31, 2016 (in millions) Gross Amount Accumulated Amortization Net Amount Gross Amount Accumulated Amortization Net Amount Customer lists Up to 6 years $ 1,104 $ (1,016 ) $ 88 $ 1,104 $ (894 ) $ 210 Trademarks and patents Up to 19 years 307 (192 ) 115 303 (156 ) 147 Other Up to 28 years 49 (35 ) 14 50 (31 ) 19 Other intangible assets $ 1,460 $ (1,243 ) $ 217 $ 1,457 $ (1,081 ) $ 376 Amortization expense for intangible assets subject to amortization was $163 million , $220 million and $276 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The estimated aggregate future amortization expense for intangible assets subject to amortization are summarized below: (in millions) Estimated Future Amortization Year Ending December 31, 2018 $ 105 2019 52 2020 35 2021 14 2022 4 Thereafter 7 Total $ 217

Fair Value Measurements and Der

Fair Value Measurements and Derivative Instruments	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements and Derivative Instruments	Note 6 – Fair Value Measurements and Derivative Instruments Embedded Derivative Instruments In connection with the business combination with MetroPCS, we issued senior reset notes to Deutsche Telekom. The interest rates were adjusted at the reset dates to rates defined in the applicable supplemental indentures to manage interest rate risk related to the senior reset notes. We determined certain components of the reset feature are required to be bifurcated from the senior reset notes and separately accounted for as embedded derivative instruments. As of December 31, 2017 and 2016 , there were no embedded derivatives subject to interest rate volatility related to the Senior Reset Notes to affiliates. The fair value of our embedded derivatives was determined using a lattice-based valuation model by determining the fair value of the senior reset notes with and without the embedded derivatives included. The fair value of the senior reset notes with the embedded derivatives utilizes the contractual term of each senior reset note, reset rates calculated based on the spread between specified yield curves and the yield curve on certain T-Mobile long-term debt adjusted pursuant to the applicable supplemental indentures and interest rate volatility. Interest rate volatility is a significant unobservable input (Level 3) as it is derived based on weighted risk-free rate volatility and credit spread volatility. Significant increases or decreases in the weighting of risk-free volatility and credit spread volatility, in isolation, would result in a higher or lower fair value of the embedded derivatives. The embedded derivatives were classified as Level 3 in the fair value hierarchy. The fair value of embedded derivative instruments by balance sheet location and level were as follows: December 31, 2017 (in millions) Level 1 Level 2 Level 3 Total Other long-term liabilities $ — $ — $ 66 $ 66 December 31, 2016 (in millions) Level 1 Level 2 Level 3 Total Other long-term liabilities $ — $ — $ 118 $ 118 The following table summarizes the gain (loss) activity related to embedded derivatives instruments recognized in Interest expense to affiliates: Year Ended December 31, (in millions) 2017 2016 2015 Embedded derivatives $ 52 $ 25 $ (148 ) Assets and Liabilities Measured at Fair Value on a Recurring Basis The carrying amounts and fair values of our assets and liabilities measured at fair value on a recurring basis included in our Consolidated Balance Sheets were as follows: Level within the Fair Value Hierarchy December 31, 2017 December 31, 2016 (in millions) Carrying Amount Fair Value Carrying Amount Fair Value Assets: Deferred purchase price assets 3 $ 745 $ 745 $ 659 $ 659 Liabilities: Guarantee liabilities 3 105 105 135 135 The principal amounts and fair values of our short-term and long-term debt included in our Consolidated Balance Sheets were as follows: Level within the Fair Value Hierarchy December 31, 2017 December 31, 2016 (in millions) Principal Amount Fair Value Principal Amount Fair Value Liabilities: Senior Notes to third parties 1 $ 11,850 $ 12,540 $ 18,600 $ 19,584 Senior Notes to affiliates 2 7,500 7,852 — — Incremental Term Loan Facility to affiliates 2 4,000 4,020 — — Senior Reset Notes to affiliates 2 3,100 3,260 5,600 5,955 Senior Secured Term Loans 2 — — 1,980 2,005 Long-term Debt The fair value of our Senior Notes to third parties was determined based on quoted market prices in active markets, and therefore was classified as Level 1 within the fair value hierarchy. The fair values of the Senior Notes to affiliates , Incremental Term Loan Facility to affiliates , Senior Reset Notes to affiliates and Senior Secured Term Loans were determined based on a discounted cash flow approach using quoted prices of instruments with similar terms and maturities and an estimate for our standalone credit risk. Accordingly, our Senior Notes to affiliates , Incremental Term Loan Facility to affiliates , Senior Reset Notes to affiliates and Senior Secured Term Loans were classified as Level 2 within the fair value hierarchy. Although we have determined the estimated fair values using available market information and commonly accepted valuation methodologies, considerable judgment was required in interpreting market data to develop fair value estimates for the Senior Notes to affiliates , Incremental Term Loan Facility to affiliates , Senior Reset Notes to affiliates and Senior Secured Term Loans to affiliates. The fair value estimates were based on information available as of December 31, 2017 and 2016 . As such, our estimates are not necessarily indicative of the amount we could realize in a current market exchange. Deferred Purchase Price Assets In connection with the sales of certain service and EIP receivables pursuant to the sale arrangements, we have deferred purchase price assets measured at fair value that are based on a discounted cash flow model using unobservable Level 3 inputs, including customer default rates. See Note 3 – Sales of Certain Receivables for further information . Guarantee Liabilities We offer certain device trade-in programs, including JUMP!, which provide eligible customers a specified-price trade-in right to upgrade their device. For customers who are enrolled in a device trade-in program, we defer the portion of equipment revenues which represents the estimated fair value of the specified-price trade-in right guarantee incorporating the expected probability and timing of the handset upgrade and the estimated fair value of the used handset which is returned. Accordingly, our guarantee liabilities were classified as Level 3 within the fair value hierarchy. When customers upgrade their device, the difference between the trade-in credit to the customer and the fair value of the returned device is recorded against the guarantee liabilities. Guarantee liabilities are included in Other current liabilities in our Consolidated Balance Sheets . The total estimated remaining gross EIP receivable balances of all enrolled handset upgrade program customers, which are the remaining EIP amounts underlying the JUMP! guarantee, including EIP receivables that have been sold, was $2.5 billion as of December 31, 2017 . This is not an indication of our expected loss exposure as it does not consider the expected fair value of the used handset or the probability and timing of the trade-in.

Debt

Debt	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt	Note 7 – Debt Debt was as follows: (in millions) December 31, December 31, 5.250% Senior Notes due 2018 $ — $ 500 6.464% Senior Notes due 2019 — 1,250 6.288% Senior Reset Notes to affiliates due 2019 — 1,250 6.542% Senior Notes due 2020 — 1,250 6.625% Senior Notes due 2020 — 1,000 6.366% Senior Reset Notes to affiliates due 2020 — 1,250 6.250% Senior Notes due 2021 — 1,750 6.633% Senior Notes due 2021 — 1,250 5.300% Senior Notes to affiliates due 2021 2,000 — 8.097% Senior Reset Notes to affiliates due 2021 1,250 1,250 6.125% Senior Notes due 2022 1,000 1,000 6.731% Senior Notes due 2022 — 1,250 4.000% Senior Notes due 2022 500 — 4.000% Senior Notes to affiliates due 2022 1,000 — 8.195% Senior Reset Notes to affiliates due 2022 1,250 1,250 Incremental term loan facility to affiliates due 2022 2,000 — 6.000% Senior Notes due 2023 1,300 1,300 6.625% Senior Notes due 2023 1,750 1,750 6.836% Senior Notes due 2023 600 600 9.332% Senior Reset Notes to affiliates due 2023 600 600 6.000% Senior Notes due 2024 1,000 1,000 6.500% Senior Notes due 2024 1,000 1,000 6.000% Senior Notes to affiliates due 2024 1,350 — 6.000% Senior Notes to affiliates due 2024 650 — Incremental term loan facility to affiliates due 2024 2,000 — 5.125% Senior Notes due 2025 500 — 6.375% Senior Notes due 2025 1,700 1,700 5.125% Senior Notes to affiliates due 2025 1,250 — 6.500% Senior Notes due 2026 2,000 2,000 5.375% Senior Notes due 2027 500 — 5.375% Senior Notes to affiliates Due 2027 1,250 — Senior Secured Term Loans — 1,980 Capital leases 1,824 1,425 Unamortized premium from purchase price allocation fair value adjustment 78 212 Unamortized premium on debt to affiliates 59 — Unamortized discount on Senior Secured Term Loans — (8 ) Unamortized discount on affiliates Senior Notes (73 ) — Debt issuance cost (19 ) (23 ) Total debt 28,319 27,786 Less: Current portion of Senior Secured Term Loans — 20 Less: Current portion of Senior Notes 999 — Less: Current portion of capital leases 613 334 Total long-term debt $ 26,707 $ 27,432 Classified on the balance sheet as: Long-term debt $ 12,121 $ 21,832 Long-term debt to affiliates 14,586 5,600 Total long-term debt $ 26,707 $ 27,432 Debt to Third Parties Issuances and Borrowings During the year ended December 31, 2017 , we issued the following Senior Notes: (in millions) Principal Issuances Issuance Costs Net Proceeds from Issuance of Long-Term Debt 4.000% Senior Notes due 2022 $ 500 $ 2 $ 498 5.125% Senior Notes due 2025 500 2 498 5.375% Senior Notes due 2027 500 1 499 Total of Senior Notes issued $ 1,500 $ 5 $ 1,495 On March 16, 2017, T-Mobile USA and certain of its affiliates, as guarantors, issued a total of $1.5 billion of public Senior Notes with various interest rates and maturity dates. Issuance costs related to the public debt issuance totaled $5 million for the year ended December 31, 2017 . We used the net proceeds of $1.495 billion from the transaction to redeem callable high yield debt. On January 25, 2018, T-Mobile USA and certain of its affiliates, as guarantors, (i) issued $1.0 billion of public 4.500% Senior Notes due 2026 and (ii) issued $1.5 billion of public 4.750% Senior Notes due 2028. We intend to use the net proceeds of $2.493 billion from the transaction to redeem up to $1.75 billion of 6.625% Senior Notes due 2023 , and up to $600 million of 6.836% Senior Notes due 2023 , with the balance to be used for general corporate purposes, including partial pay down of borrowings under our revolving credit facility with DT. Issuance costs related to the public debt issuance totaled approximately $7 million . Notes Redemptions During the year ended December 31, 2017 , we made the following note redemptions: (in millions) Principal Amount Write-off of Premiums, Discounts and Issuance Costs (1) Call Penalties (1) (2) Redemption Redemption Price 6.625% Senior Notes due 2020 $ 1,000 $ (45 ) $ 22 February 10, 2017 102.208 % 5.250% Senior Notes due 2018 500 1 7 March 4, 2017 101.313 % 6.250% Senior Notes due 2021 1,750 (71 ) 55 April 1, 2017 103.125 % 6.464% Senior Notes due 2019 1,250 — — April 28, 2017 100.000 % 6.542% Senior Notes due 2020 1,250 — 21 April 28, 2017 101.636 % 6.633% Senior Notes due 2021 1,250 — 41 April 28, 2017 103.317 % 6.731% Senior Notes due 2022 1,250 — 42 April 28, 2017 103.366 % Total note redemptions $ 8,250 $ (115 ) $ 188 (1) Write-off of premiums, discounts, issuance costs and call penalties are included in Other expense, net in our Consolidated Statements of Comprehensive Income . Write-off of premiums, discounts and issuance costs are included in Other, net within Net cash provided by operating activities in our Consolidated Statements of Cash Flows . (2) The call penalty is the excess paid over the principal amount. Call penalties are included within Net cash provided by operating activities in our Consolidated Statements of Cash Flows . Prior to December 31, 2017 , we delivered a notice of redemption on $1.0 billion aggregate principal amount of our 6.125% Senior Notes due 2022 . The notes were redeemed on January 15, 2018, at a redemption price equal to 103.063% of the principal amount of the notes (plus accrued and unpaid interest thereon). The redemption premium was approximately $31 million and the write-off of issuance costs was approximately $1 million . The outstanding principal amount was reclassified from Long-term debt to Short-term debt in our Consolidated Balance Sheets as of December 31, 2017 . Debt to Affiliates Issuances and Borrowings During the year ended December 31, 2017 , we made the following borrowings: (in millions) Net Proceeds from Issuance of Long-Term Debt Extinguishments Write-off of Discounts and Issuance Costs (1) LIBOR plus 2.00% Senior Secured Term Loan due 2022 $ 2,000 $ — $ — LIBOR plus 2.00% Senior Secured Term Loan due 2024 2,000 — — LIBOR plus 2.750% Senior Secured Term Loan (2) — (1,980 ) 13 Total $ 4,000 $ (1,980 ) $ 13 (1) Write-off of discounts and issuance costs are included in Other expense, net in our Consolidated Statements of Comprehensive Income and Other, net within Net cash provided by operating activities in our Consolidated Statements of Cash Flows . (2) Our Senior Secured Term Loan extinguished during the year ended December 31, 2017 was Third Party debt. On January 25, 2017, T-Mobile USA, Inc. (“T-Mobile USA”), and certain of its affiliates, as guarantors, entered into an agreement to borrow $4.0 billion under a secured term loan facility (“Incremental Term Loan Facility”) with DT, our majority stockholder, to refinance $1.98 billion of outstanding senior secured term loans under its Term Loan Credit Agreement dated November 9, 2015, with the remaining net proceeds from the transaction used to redeem callable high yield debt. The Incremental Term Loan Facility increased DT’s incremental term loan commitment provided to T-Mobile USA under that certain First Incremental Facility Amendment dated as of December 29, 2016, from $660 million to $2.0 billion and provided T-Mobile USA with an additional $2.0 billion incremental term loan commitment. On January 31, 2017, the loans under the Incremental Term Loan Facility were drawn in two tranches: (i) $2.0 billion of which bears interest at a rate equal to a per annum rate of LIBOR plus a margin of 2.00% and matures on November 9, 2022, and (ii) $2.0 billion of which bears interest at a rate equal to a per annum rate of LIBOR plus a margin of 2.25% and matures on January 31, 2024. In July 2017, we repriced the $2.0 billion Incremental Term Loan Facility maturing on January 31, 2024, with DT by reducing the interest rate to a per annum rate of LIBOR plus a margin of 2.00% . No issuance fees were incurred related to this debt agreement for the year ended December 31, 2017 . On March 31, 2017, the Incremental Term Loan Facility was amended to waive all interim principal payments. The outstanding principal balance will be due at maturity. During the year ended December 31, 2017 , we issued the following Senior Notes to DT: (in millions) Principal Issuances (Redemptions) Discounts (1) Net Proceeds from Issuance of Long-Term Debt 4.000% Senior Notes due 2022 $ 1,000 $ (23 ) $ 977 5.125% Senior Notes due 2025 1,250 (28 ) 1,222 5.375% Senior Notes due 2027 (2) 1,250 (28 ) 1,222 6.288% Senior Reset Notes due 2019 (1,250 ) — (1,250 ) 6.366% Senior Reset Notes due 2020 (1,250 ) — (1,250 ) Total $ 1,000 $ (79 ) $ 921 (1) Discounts reduce Proceeds from issuance of long-term debt and are included within Net cash (used in) provided by financing activities in our Consolidated Statements of Cash Flows . (2) In April 2017, we issued to DT $750 million in aggregate principal amount of the 5.375% Senior Notes due 2027 , and in September 2017, we issued to DT the remaining $500 million in aggregate principal amount of the 5.375% Senior Notes due 2027 . On March 13, 2017, DT agreed to purchase a total of $3.5 billion in aggregate principal amounts of Senior Notes with various interest rates and maturity dates (the “new DT Notes”). Through net settlement in April 2017, we issued to DT a total of $3.0 billion in aggregate principal amount of the new DT Notes and redeemed the $2.5 billion in outstanding aggregate principal amount of Senior Reset Notes with various interest rates and maturity dates (the “old DT Notes”). The redemption prices of the old DT Notes were 103.144% and 103.183% , resulting in a total of $79 million in early redemption fees. These early redemption fees were recorded as discounts on the issuance of the new DT Notes. In September 2017, we issued to DT $500 million in aggregate principal amount of 5.375% Senior Notes due 2027 , which is the final tranche of the new DT Notes. We were not required to pay any underwriting fees or issuance costs in connection with the issuance of the notes. Net proceeds from the issuance of the new DT Notes were $921 million and are included in Proceeds from issuance of long-term debt in our Consolidated Statements of Cash Flows . On May 9, 2017, we exercised our option under existing purchase agreements and issued the following Senior Notes to DT: (in millions) Principal Issuances Premium Net Proceeds from Issuance of Long-Term Debt 5.300% Senior Notes due 2021 $ 2,000 $ — $ 2,000 6.000% Senior Notes due 2024 1,350 40 1,390 6.000% Senior Notes due 2024 650 24 674 Total $ 4,000 $ 64 $ 4,064 The proceeds were used to fund a portion of the purchase price of spectrum licenses won in the 600 MHz spectrum auction. Net proceeds from these issuances include $64 million in debt premiums. See Note 5 - Goodwill, Spectrum Licenses and Other Intangible Assets for further information. On January 22, 2018, DT agreed to purchase $1.0 billion in aggregate principal amount of 4.500% Senior Notes due 2026 and $1.5 billion in aggregate principal amount of 4.750% Senior Notes due 2028 directly from T-Mobile USA and certain of its affiliates, as guarantors, with no underwriting discount (the “DT Notes”). DT has agreed that the payment for the DT notes will be made by delivery of $1.25 billion in aggregate principal amount of 8.097% Senior Reset Notes due 2021 and $1.25 billion in aggregate principal amount of 8.195% Senior Reset Notes due 2022 (collectively, the “DT Senior Reset Notes”) held by DT and which T-Mobile USA will have called for redemption, in exchange for the DT notes. In connection with such exchange, we will pay DT in cash the premium portion of the redemption price set forth in the indenture governing the DT Senior Reset Notes, plus accrued but unpaid interest on the DT Senior Reset Notes to, but not including, the exchange date. The closing of the issuance and sale of the DT notes to DT, and exchange of the DT Senior Reset Notes, is expected to occur on or about April 30, 2018. Capital Leases Capital lease agreements primarily relate to network equipment with varying expiration terms through 2031 . Future minimum payments required under capital leases, including interest and maintenance, over their remaining terms are summarized below: (in millions) Future Minimum Payments Year Ended December 31, 2018 $ 682 2019 634 2020 338 2021 151 2022 67 Thereafter 172 Total $ 2,044 Included in Total Interest $ 169 Maintenance 51 Financing Arrangements We maintain a handset financing arrangement with Deutsche Bank AG (“Deutsche Bank”), which allows for up to $108 million in borrowings. Under the handset financing arrangement, we can effectively extend payment terms for invoices payable to certain handset vendors. The interest rate on the handset financing arrangement is determined based on LIBOR plus a specified margin per the arrangement. Obligations under the handset financing arrangement are included in Short-term debt in our Consolidated Balance Sheets . In 2016 , we utilized and repaid $100 million under the financing arrangement. As of December 31, 2017 and 2016 , there was no outstanding balance. We maintain vendor financing arrangements with our primary network equipment suppliers. Under the respective agreements, we can obtain extended financing terms. The interest rate on the vendor financing arrangements is determined based on the difference between LIBOR and a specified margin per the agreements. Obligations under the vendor financing arrangements are included in Short-term debt in our Consolidated Balance Sheets . In 2017 , we utilized and repaid $300 million under the financing arrangement. As of December 31, 2017 and 2016 , there was no outstanding balance. Revolving Credit Facility and Standby Letters of Credit We had an unsecured revolving credit facility with Deutsche Telekom which allowed for up to $500 million in borrowings. In December 2016, we terminated our $500 million unsecured revolving credit facility with Deutsche Telekom. In December 2016, T-Mobile USA entered into a $2.5 billion revolving credit facility with Deutsche Telekom which comprised of (i) a three -year $1.0 billion unsecured revolving credit agreement and (ii) a three -year $1.5 billion secured revolving credit agreement. The applicable margin for the Unsecured Revolving Credit Facility ranges from 2.00% to 3.25% per annum for Eurodollar Rate loans. The applicable margin for the Secured Revolving Credit Facility ranges from 1.00% to 1.75% per annum for Eurodollar Rate loans. As of December 31, 2017 and 2016 , there were no outstanding borrowings under the revolving credit facility. In January 2018, we utilized proceeds under the revolving credit facility to redeem $1.0 billion in aggregate principal amount of our 6.125% Senior Notes due 2022 and for general corporate purposes. As of February 5, 2018, there were no outstanding borrowings on the revolving credit facility. The Proceeds and borrowings from the revolving credit facility are presented in Proceeds from borrowing on revolving credit facility and Repayments of revolving credit facility within Net cash (used in) provided by financing activities in our Consolidated Statements of Cash Flows . For the purposes of securing our obligations to provide handset insurance services, we maintain an agreement for standby letters of credit with JP Morgan Chase Bank, N.A. (“JP Morgan Chase”). For purposes of securing our general purpose obligations, we maintain a letter of credit reimbursement agreement with Deutsche Bank. The following table summarizes the outstanding standby letters of credit under each agreement: (in millions) December 31, December 31, JP Morgan Chase $ 20 $ 20 Deutsche Bank 59 54 Total outstanding balance $ 79 $ 74

Tower Obligations

Tower Obligations	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Tower Obligations	Note 8 - Tower Obligations In 2012, we conveyed to Crown Castle International Corp. (“CCI”) the exclusive right to manage and operate approximately 7,100 T-Mobile-owned wireless communication tower sites (“CCI Tower Sites”) in exchange for net proceeds of $2.5 billion (“2012 Tower Transaction”). Rights to approximately 6,200 of the tower sites were transferred to CCI via a Master Prepaid Lease with site lease terms ranging from 23 to 37 years (“CCI Lease Sites”), while the remaining tower sites were sold to CCI (“CCI Sales Sites”). CCI has fixed-price purchase options for these towers totaling approximately $2.0 billion , based on the estimated fair market value at the end of the lease term. We lease back space at certain tower sites for an initial term of ten years , followed by optional renewals at customary terms. In 2015, we conveyed to Phoenix Tower International (“PTI”) the exclusive right to manage and operate approximately 600 T-Mobile-owned wireless communication tower sites (“PTI Tower Sites”) in exchange for net proceeds of approximately $140 million (“2015 Tower Transaction”). As of December 31, 2017 , rights to approximately 200 of the tower sites remain operated by PTI under a management agreement (“PTI Managed Sites”). We lease back space at certain tower sites for an initial term of ten years , followed by optional renewals at customary terms. Assets and liabilities associated with the operation of certain of the tower sites were transferred to SPEs. Assets included ground lease agreements or deeds for the land on which the towers are situated, the towers themselves and existing subleasing agreements with other mobile network operator tenants, who lease space at the tower sites. Liabilities included the obligation to pay ground lease rentals, property taxes and other executory costs. Upon closing of the 2012 Tower Transaction, CCI acquired all of the equity interests in the SPEs containing CCI Sales Sites and an option to acquire the CCI Lease Sites at the end of their respective lease terms and entered into a master lease agreement under which we agreed to lease back space at certain of the tower sites. Upon closing of the 2015 Tower Transaction, PTI acquired all of the equity interests in the SPEs containing PTI Sales Sites and entered into a master lease agreement under which we agreed to lease back space at certain of the tower sites. We determined the SPEs containing the CCI Lease Sites (“Lease Site SPEs”) are VIEs as the Company's equity investment lacks the power to direct the activities that most significantly impact the economic performance of the VIEs. These activities include managing tenants and underlying ground leases, performing repair and maintenance on the towers, the obligation to absorb expected losses and the right to receive the expected future residual returns from the purchase option to acquire the CCI Lease Sites. As we determined that we are not the primary beneficiary and do not have a controlling financial interest in the Lease Site SPEs, the balances and operating results of the Lease Site SPEs are not included in our consolidated financial statements. Due to our continuing involvement with the tower sites, we determined that we were precluded from applying sale-leaseback accounting. We recorded long-term financial obligations in the amount of the net proceeds received and recognized interest on the tower obligations at a rate of approximately 8% for the 2012 Tower Transaction and 5% for the 2015 Tower Transaction using the effective interest method. The tower obligations are increased by interest expense and amortized through contractual leaseback payments made by us to CCI or PTI and through estimated future net cash flows generated and retained by CCI or PTI from operation of the tower sites. Our historical tower site asset costs continue to be reported in Property and equipment, net in our Consolidated Balance Sheets and are depreciated. The following table summarizes the impacts to the Consolidated Balance Sheets : (in millions) December 31, December 31, Property and equipment, net $ 402 $ 485 Long-term financial obligation 2,590 2,621 Future minimum payments related to the tower obligations are expected to be approximately $189 million in 2018 , $379 million in total for 2019 and 2020 , $381 million in total for 2021 and 2022 and $1.0 billion in total for years thereafter. We are contingently liable for future ground lease payments through the remaining term of the CCI Lease Sites. These contingent obligations are not included in the above table as any amount due is contractually owed by CCI based on the subleasing arrangement. See Note 13 – Commitments and Contingencies for further information.

Employee Compensation and Benef

Employee Compensation and Benefit Plans	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee Compensation and Benefit Plans	Note 9 – Employee Compensation and Benefit Plans Under our 2013 Omnibus Incentive Plan (the “Incentive Plan”), we are authorized to issue up to 63 million shares of our common stock. Under the Incentive Plan, we can grant stock options, stock appreciation rights, restricted stock, restricted stock units (“RSUs”), and performance awards to eligible employees, consultants, advisors and non-employee directors. As of December 31, 2017 , there were 15 million shares of common stock available for future grants under the Incentive Plan. In January 2018, we closed on our previously announced acquisition of Layer3 TV, Inc. (“Layer3 TV”). Upon closing, the Layer3 TV 2013 Stock Plan and stock restriction agreements between Layer3 and certain employees were added to the Registration Statement related to the Incentive Plan. See Note 15 - Subsequent Events for further information regarding the Layer3 TV acquisitions. We grant RSUs to eligible employees and certain non-employee directors and performance-based restricted stock units (“PRSUs”) to eligible key executives. RSUs entitle the grantee to receive shares of our common stock at the end of a vesting period of generally up to 3 years , subject to continued service through the applicable vesting date. PRSUs entitle the holder to receive shares of our common stock at the end of a vesting period of generally up to 3 years if the applicable performance goals are achieved and generally subject to continued employment through the vesting period. The number of shares ultimately received by the holder of PRSUs is dependent on our business performance against the specified performance goal(s) over a pre-established performance period. We also maintain an employee stock purchase plan (“ESPP”), under which eligible employees can purchase our common stock at a discounted price. Stock-based compensation expense and related income tax benefits were as follows: (in millions, except shares, per share and contractual life amounts) December 31, December 31, December 31, Stock-based compensation expense $ 306 $ 235 $ 201 Income tax benefit related to stock-based compensation 73 80 71 Realized excess tax benefit — — 79 Weighted average fair value per stock award granted 60.21 45.07 35.56 Unrecognized compensation expense 445 389 327 Weighted average period to be recognized (years) 1.9 2.0 2.0 Fair value of stock awards vested 503 354 445 Stock Awards RSU and PRSU Awards The following activity occurred under the RSU and PRSU awards: (in millions, except shares, per share and contractual life amounts) Number of Units (1) Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Nonvested, December 31, 2016 15,715,391 $ 37.93 1.1 $ 904 Granted 7,133,359 60.21 Vested (8,338,271 ) 35.47 Forfeited (814,936 ) 49.02 Nonvested, December 31, 2017 13,695,543 50.38 1.1 870 (1) PRSUs included in the table above are shown at target. Share payout can range from 0 to 200% based on different performance outcomes. Payment of the underlying shares in connection with the vesting of stock awards generally triggers a tax obligation for the employee, which is required to be remitted to the relevant tax authorities. We have agreed to withhold stock otherwise issuable under the award to cover certain of these tax obligations, with the net shares issued to the employee accounted for as outstanding common stock. We withheld 2,754,721 and 2,605,807 shares of stock to cover tax obligations associated with the payment of shares upon vesting of stock awards and remitted cash of $166 million and $121 million to the appropriate tax authorities for the years ended December 31, 2017 and 2016 , respectively. Employee Stock Purchase Plan Our ESPP allows eligible employees to contribute up to 15% of their eligible earnings toward the semi-annual purchase of our common stock at a discounted price, subject to an annual maximum dollar amount. Employees can purchase stock at a 15% discount applied to the closing stock price on the first or last day of the six -month offering period, whichever price is lower. The number of shares issued under our ESPP was 1,832,043 and 1,905,534 for the years ended December 31, 2017 and 2016 , respectively. Stock Options Prior to the business combination, MetroPCS had established the MetroPCS Communications, Inc. 2010 Equity Incentive Compensation Plan, the Amended and Restated MetroPCS Communications, Inc. 2004 Equity Incentive Compensation Plan and the Second Amended and Restated 1995 Stock Option Plan (“Predecessor Plans”). Following stockholder approval of the Incentive Plan, no new awards have been or may be granted under the Predecessor Plans. The following activity occurred under the Predecessor Plans: Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (Years) Outstanding and exercisable, December 31, 2016 833,931 $ 31.75 2.3 Exercised (450,873 ) 44.18 Expired (9,900 ) 45.76 Outstanding and exercisable, December 31, 2017 373,158 16.36 2.8 Stock options exercised under the Predecessor Plans generated proceeds of approximately $21 million and $29 million for the years ended December 31, 2017 and 2016 , respectively. Employee Retirement Savings Plan We sponsor a retirement savings plan for the majority of our employees under section 401(k) of the Internal Revenue Code and similar plans. The plans allow employees to contribute a portion of their pretax income in accordance with specified guidelines. The plans provide that we match a percentage of employee contributions up to certain limits. Employer matching contributions were $87 million , $83 million and $73 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. Legacy Long-Term Incentive Plan Prior to the business combination with MetroPCS Communications, Inc., we maintained a performance-based Long-Term Incentive Plan (“LTIP”) which aligned to our long-term business strategy. As of December 31, 2017 and 2016 , there were no LTIP awards outstanding and no new awards are expected to be granted under the LTIP. Compensation expense reported within operating expenses related to our LTIP and payments to participants related to our LTIP were as follows: (in millions) December 31, December 31, December 31, Compensation expense $ — $ — $ 27 Payments — 52 57

Repurchases of Common Stock

Repurchases of Common Stock	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Repurchases of Common Stock	Note 10 – Repurchases of Common Stock On December 6, 2017, our Board of Directors authorized a stock repurchase program for up to $1.5 billion of our common stock through December 31, 2018. Under the repurchase program, repurchases can be made from time to time using a variety of methods, which may include open market purchases, privately negotiated transactions or otherwise, all in accordance with the rules of the Securities and Exchange Commission and other applicable legal requirements. The specific timing, price and size of purchases will depend on prevailing stock prices, general economic and market conditions, and other considerations. The repurchase program does not obligate us to acquire any particular amount of common stock, and the repurchase program may be suspended or discontinued at any time at our discretion. Repurchased shares are retired. We also understand that Deutsche Telekom AG, our majority stockholder, or its affiliates, is considering plans to purchase additional shares of our common stock. Such purchases would likely take place through December 31, 2018, all in accordance with the rules of the Securities and Exchange Commission and other applicable legal requirements. The following table summarizes information regarding repurchases of our common stock: (In millions, except shares and per share price) Number of Shares Repurchased Average Price Paid Per Share Total Purchase Price Year Ended December 31, 2017 7,010,889 $ 63.34 $ 444 From the inception of the repurchase program through February 5, 2018, we repurchased approximately 12.3 million shares at an average price per share of $63.68 for a total purchase price of approximately $783 million . As of February 5, 2018, there was approximately $717 million of repurchase authority remaining.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Note 11 – Income Taxes Our sources of Income before income taxes were as follows: Year Ended December 31, (in millions) 2017 2016 2015 U.S. $ 3,274 $ 2,286 $ 898 Puerto Rico (113 ) 41 80 Income before income taxes $ 3,161 $ 2,327 $ 978 Income tax expense is summarized as follows: Year Ended December 31, (in millions) 2017 2016 2015 Current tax benefit (expense) Federal $ — $ 66 $ 30 State (28 ) (29 ) (2 ) Puerto Rico (1 ) 10 (17 ) Total current tax benefit (expense) (29 ) 47 11 Deferred tax benefit (expense) Federal 1,182 (804 ) (281 ) State 173 (96 ) 37 Puerto Rico 49 (14 ) (12 ) Total deferred tax benefit (expense) 1,404 (914 ) (256 ) Total income tax benefit (expense) $ 1,375 $ (867 ) $ (245 ) The reconciliation between the U.S. federal statutory income tax rate and our effective income tax rate is as follows: Year Ended December 31, 2017 2016 2015 Federal statutory income tax rate 35.0 % 35.0 % 35.0 % Effect of the Tax Cuts and Jobs Act (68.9 ) — — Change in valuation allowance (11.4 ) 1.0 (3.2 ) State taxes, net of federal benefit 4.8 4.0 (1.1 ) Equity-based compensation (2.4 ) (2.2 ) — Puerto Rico taxes, net of federal benefit (1.5 ) — 3.3 Permanent differences 0.5 0.6 1.6 Federal tax credits, net of reserves 0.3 (0.5 ) (9.5 ) Other, net 0.1 (0.6 ) (1.0 ) Effective income tax rate (43.5 )% 37.3 % 25.1 % Significant components of deferred income tax assets and liabilities, tax effected, are as follows: (in millions) December 31, December 31, Deferred tax assets Loss carryforwards $ 1,576 $ 1,442 Deferred rents 759 1,153 Reserves and accruals 667 1,058 Federal and state tax credits 298 284 Debt fair market value adjustment — 83 Other 403 430 Deferred tax assets, gross 3,703 4,450 Valuation allowance (273 ) (573 ) Deferred tax assets, net 3,430 3,877 Deferred tax liabilities Spectrum licenses 5,038 6,952 Property and equipment 1,840 1,732 Other intangible assets 41 119 Other 48 12 Total deferred tax liabilities 6,967 8,815 Net deferred tax liabilities $ 3,537 $ 4,938 Classified on the balance sheet as: Deferred tax liabilities $ 3,537 $ 4,938 On December 22, 2017, President Trump signed the Tax Cuts and Jobs Act of 2017 (“TCJA”) into legislation. The TCJA includes numerous changes to existing tax law, including a permanent reduction in the federal corporate income tax rate from 35% to 21% . The rate reduction takes effect on January 1, 2018. We recognized a net tax benefit of $2.2 billion associated with enactment of the TCJA in Income tax benefit (expense) in our Consolidated Statements of Comprehensive Income in the fourth quarter of 2017, primarily due to a re-measurement of deferred tax assets and liabilities. The SEC has issued Staff Accounting Bulletin (“SAB”) No. 118 which permits the recording of provisional amounts related to the impact of the TCJA during a measurement period which is not to exceed one year from the enactment date of the TCJA. We have recorded an immaterial amount for provisional items related to the TCJA in our Consolidated Statements of Comprehensive Income . As of December 31, 2017 , we have tax effected net operating loss (“NOL”) carryforwards of $1.0 billion for federal income tax purposes and $832 million for state income tax purposes, expiring through 2037. As of December 31, 2017 , our tax effected federal and state NOL carryforwards for financial reporting purposes were approximately $123 million and $242 million , respectively, less than our NOL carryforwards for federal and state income tax purposes, due to unrecognized tax benefits of the same amount. As of December 31, 2017 , we have available Alternative Minimum Tax (“AMT”) credit carryforwards of $86 million . Under the TCJA, the AMT credits will be fully recovered by 2021. We also have research and development and foreign tax credit carryforwards with a combined value of $198 million for federal income tax purposes, which begin to expire in 2018. As of December 31, 2017 and 2016 , our valuation allowance was $273 million and $573 million , respectively. The change in the valuation allowance is primarily related to a net reduction in the valuation allowance against deferred tax assets in state jurisdictions that resulted in the recognition of $359 million in net tax benefits in 2017 , partially offset by a $26 million valuation allowance established during 2017 for the impact of the TCJA on certain tax credits and a $33 million increase in the valuation allowance associated with the reduced federal benefit of state items. During 2017 , due to ongoing analysis of positive and negative evidence related to the utilization of the deferred tax assets, we determined that $319 million of the valuation allowance in certain state jurisdictions was no longer necessary. Positive evidence supporting the release of a portion of the valuation allowance included reaching a position of cumulative income over a three-year period in certain state jurisdictions as well as projecting sustained earnings in those jurisdictions. Due to this positive evidence, we reduced the valuation allowance which resulted in a decrease to Deferred tax liabilities in our Consolidated Balance Sheets . We will continue to monitor positive and negative evidence related to the utilization of the remaining deferred tax assets for which a valuation allowance continues to be provided. It is possible that our valuation allowance may change within the next twelve months. We file income tax returns in the U.S. federal jurisdiction, various state jurisdictions and in Puerto Rico. We are currently under a scope-limited examination by the U.S. Internal Revenue Service (“IRS”) and separate examinations by various states. Management does not believe the resolution of any of the audits will result in a material change to our financial condition, results of operations or cash flows. The IRS has concluded its audits of our federal tax returns through the 2013 tax year; however, NOL and other carryforwards for certain audited periods remain open for examination. We are generally closed to U.S. federal, state and Puerto Rico examination for years prior to 1998. A reconciliation of the beginning and ending amount of unrecognized tax benefits were as follows: Year Ended December 31, (in millions) 2017 2016 2015 Unrecognized tax benefits, beginning of year $ 410 $ 411 $ 388 Gross decreases to tax positions in prior periods (10 ) (5 ) (112 ) Gross increases to current period tax positions 12 4 135 Unrecognized tax benefits, end of year $ 412 $ 410 $ 411 As of December 31, 2017 and 2016 , we had $254 million and $168 million , respectively, in unrecognized tax benefits that, if recognized, would affect our annual effective tax rate. Penalties and interest on income tax assessments are included in Selling, general and administrative expenses and Interest expense, respectively, in our Consolidated Statements of Comprehensive Income. The accrued interest and penalties associated with unrecognized tax benefits are insignificant.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Note 12 – Earnings Per Share The computation of basic and diluted earnings per share was as follows: Year Ended December 31, (in millions, except shares and per share amounts) 2017 2016 2015 Net income $ 4,536 $ 1,460 $ 733 Less: Dividends on mandatory convertible preferred stock (55 ) (55 ) (55 ) Net income attributable to common stockholders - basic 4,481 1,405 678 Add: Dividends related to mandatory convertible preferred stock 55 — — Net income attributable to common stockholders - diluted $ 4,536 $ 1,405 $ 678 Weighted average shares outstanding - basic 831,850,073 822,470,275 812,994,028 Effect of dilutive securities: Outstanding stock options and unvested stock awards 9,200,873 10,584,270 9,623,910 Mandatory convertible preferred stock 30,736,504 — — Weighted average shares outstanding - diluted 871,787,450 833,054,545 822,617,938 Earnings per share - basic $ 5.39 $ 1.71 $ 0.83 Earnings per share - diluted $ 5.20 $ 1.69 $ 0.82 Potentially dilutive securities: Outstanding stock options and unvested stock awards 33,980 3,528,683 4,842,370 Mandatory convertible preferred stock — 32,238,000 32,238,000 As of December 15, 2017, 20 million shares of our preferred stock converted to approximately 32 million shares of our common stock at a conversion rate of 1.6119 common shares for each share of previously outstanding preferred stock and certain cash-in-lieu of fractional shares. Potentially dilutive securities were not included in the computation of diluted earnings per share if to do so would have been anti-dilutive.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 13 – Commitments and Contingencies Commitments Operating Leases We have non-cancellable operating leases for cell sites, switch sites, retail stores and office facilities with contractual terms expiring through 2027 . The majority of cell site leases have an initial non-cancelable term of five to ten years with several renewal options. In addition, we have operating leases for dedicated transportation lines with varying expiration terms through 2024 . Our commitments under these leases are approximately $2.4 billion in 2018 , $4.1 billion in total for 2019 and 2020 , $2.7 billion in total for 2021 and 2022 and $2.3 billion in total for years thereafter. As of December 31, 2017 , we were contingently liable for future ground lease payments related to the tower obligations. These contingent obligations are not included in the above table as the amounts due are contractually owed by CCI based on the subleasing arrangement. See Note 8 – Tower Obligations for further information. Total rent expense under operating leases, including dedicated transportation lines, was $2.9 billion , $2.8 billion and $2.8 billion for the years ended December 31, 2017 , 2016 and 2015 , respectively, and is classified as Cost of services and Selling, general and administrative in our Consolidated Statements of Comprehensive Income . In February 2018, we extended the leases related to our corporate headquarters facility. These agreements will increase our minimum lease payments by approximately $400 million in the aggregate. Purchase Commitments We have commitments for non-dedicated transportation lines with varying expiration terms through 2028 . In addition, we have commitments to purchase spectrum licenses, wireless devices, network services, equipment, software, marketing sponsorship agreements and other items in the ordinary course of business, with various terms through 2028 . These amounts are not reflective of our entire anticipated purchases under the related agreements, but are determined based on the non-cancelable quantities or termination amounts to which we are contractually obligated. We have contractual obligations to purchase certain goods and services from various other parties. Our purchase obligations are approximately $2.1 billion in 2018 , $2.2 billion in total for 2019 and 2020 , $1.5 billion in total for 2021 and 2022 and $1.0 billion in total for years thereafter. In September 2017, we entered into a UPA to acquire the remaining equity in IWS, a 54% owned unconsolidated subsidiary, for a purchase price of $25 million . In January 2018, we closed on the purchase agreement and received the IWS spectrum licenses, among other assets. See Note 5 - Goodwill, Spectrum Licenses and Other Intangible Assets for further information. On January 22, 2018, we completed our acquisition of television innovator Layer3 TV for consideration of approximately $325 million , subject to customary working capital and other post-closing adjustments. Upon closing of the transaction, Layer3 TV became a wholly-owned consolidated subsidiary. This transaction represents an opportunity for us to acquire a unique and complementary service and represents a progression in our video strategy, which began with Binge On, was strengthened with Netflix On Us, and will expand further with Layer3 TV’s management, technology, and content relationships which will enable us to bring the Un-carrier philosophy to video. Our first-quarter 2018 operating results will include the results of Layer3 TV from the date of acquisition. Our consolidated balance sheet will include the assets and liabilities of Layer3 TV, such as intangibles assets acquired, which are being appraised by a third-party and include various assumptions in determining fair value. Renewable Energy Purchase Agreements In January 2017, T-Mobile USA entered into a REPA with Red Dirt Wind Project, LLC. The agreement is based on the expected operation of a wind energy-generating facility located in Oklahoma and will remain in effect until the twelfth anniversary of the facility’s entry into commercial operation. The facility began commercial operations in January 2018. The REPA consists of two components: (1) an energy forward agreement that is net settled based on energy prices and the energy output generated by the facility and (2) a commitment to purchase the renewable energy credits (“RECs”) associated with the energy output generated by the facility. T-Mobile USA will net settle the forward agreement and acquire the RECs monthly by paying, or receiving, an aggregate net payment based on two variables (1) the facility’s energy output, which has an estimated maximum capacity of approximately 160 megawatts and (2) the difference between (a) an initial fixed price, subject to annual escalation, and (b) current local marginal energy prices during the monthly settlement period. We have determined that the REPA does not meet the definition of a derivative because the expected energy output of the facility may not be reliably estimated (the arrangement lacks a notional amount). The REPA does not contain any unconditional purchase obligations because amounts under the agreement are not fixed and determinable. Our participation in the REPA did not require an upfront investment or capital commitment. We do not control the activities that most significantly impact the energy-generating facility nor do we receive specific energy output from it. No amounts were settled under the agreement during the year ended December 31, 2017 . In August 2017, T-Mobile USA entered into a REPA with Solomon Forks Wind Project, LLC. The agreement is based on the expected operation of a wind energy-generating facility located in Kansas and will remain in effect until the fifteenth anniversary of the facility’s entry into commercial operation. Commercial operation of the facility is expected to occur by the end of 2018. The REPA consists of two components: (1) an energy forward agreement that is net settled based on energy prices and the energy output generated by the facility and (2) a commitment to purchase the environmental attributes (“EACs”) associated with the energy output generated by the facility. T-Mobile USA will net settle the forward agreement and acquire the EACs monthly by paying, or receiving, an aggregate net payment based on two variables (1) the facility’s energy output, which has an estimated maximum capacity of approximately 160 megawatts and (2) the difference between (a) an initial fixed price, subject to annual escalation, and (b) current local marginal energy prices during the monthly settlement period. We have determined that the REPA does not meet the definition of a derivative because the expected energy output of the facility may not be reliably estimated (the arrangement lacks a notional amount). The REPA does not contain any unconditional purchase obligations because amounts under the agreement are not fixed and determinable. Our participation in the REPA did not require an upfront investment or capital commitment. We do not control the activities that most significantly impact the energy-generating facility nor do we receive specific energy output from it. No amounts were settled under the agreement during the year ended December 31, 2017 . Contingencies and Litigation We are involved in various lawsuits, claims, government agency investigations and enforcement actions, and other proceedings (“Litigation Matters”) that arise in the ordinary course of business, which include claims of patent infringement (most of which are asserted by non-practicing entities primarily seeking monetary damages), class actions, and proceedings to enforce FCC rules and regulations. The Litigation Matters described above have progressed to various stages and some of them may proceed to trial, arbitration, hearing or other adjudication that could result in fines, penalties, or awards of monetary or injunctive relief in the coming 12 months, if they are not otherwise resolved. We have established an accrual with respect to certain of these matters, where appropriate, which is reflected in the consolidated financial statements but that we do not consider, individually or in the aggregate, material. An accrual is established when we believe it is both probable that a loss has been incurred and an amount can be reasonably estimated. For other matters, where we have not determined that a loss is probable or because the amount of loss cannot be reasonably estimated, we have not recorded an accrual due to various factors typical in contested proceedings, including but not limited to: uncertainty concerning legal theories and their resolution by courts or regulators; uncertain damage theories and demands; and a less than fully developed factual record. While we do not expect that the ultimate resolution of these proceedings, individually or in the aggregate, will have a material adverse effect on our financial position, an unfavorable outcome of some or all of these proceedings could have a material adverse impact on results of operations or cash flows for a particular period. This assessment is based on our current understanding of relevant facts and circumstances. As such, our view of these matters is subject to inherent uncertainties and may change in the future.

Additional Financial Informatio

Additional Financial Information	12 Months Ended
	Dec. 31, 2017
Supplemental Financial Statement Elements [Abstract]
Additional Financial Information	Note 14 – Additional Financial Information Supplemental Consolidated Balance Sheets Information Accounts Payable and Accrued Liabilities Accounts payable and accrued liabilities are summarized as follows: (in millions) December 31, December 31, Accounts payable $ 6,182 $ 5,163 Payroll and related benefits 614 559 Property and other taxes, including payroll 620 525 Interest 253 423 Commissions 324 159 Network decommissioning 92 101 Toll and interconnect 109 85 Advertising 46 44 Other 288 93 Accounts payable and accrued liabilities $ 8,528 $ 7,152 Book overdrafts included in accounts payable and accrued liabilities were $455 million and $356 million as of December 31, 2017 and 2016 , respectively. Hurricane Impacts During the third and fourth quarters of 2017, our operations in Texas, Florida and Puerto Rico experienced losses related to hurricanes. The impact to operating income for the year ended December 31, 2017 , from lost revenue, assets damaged or destroyed and other hurricane related costs was a decrease of $201 million , net of insurance recoveries. We expect additional expenses to be incurred and customer activity to be impacted in the first quarter of 2018, primarily related to our operations in Puerto Rico. We have recognized insurance recoveries related to those hurricane losses in the amount of approximately $93 million for the year ended December 31, 2017 as an offset to the costs incurred within Cost of services in our Consolidated Statements of Comprehensive Income and as an increase to Other current assets in our Consolidated Balance Sheets . We continue to assess the damage of the hurricanes and work with our insurance carriers to submit claims for property damage and business interruption. We expect to record additional insurance recoveries related to these hurricanes in future periods. Supplemental Consolidated Statements of Comprehensive Income Information Related Party Transactions We have related party transactions associated with Deutsche Telekom or its affiliates in the ordinary course of business, which are included in the consolidated financial statements. The following table summarizes the impact of significant transactions with Deutsche Telekom or its affiliates included in operating expenses in the Consolidated Statements of Comprehensive Income : Year Ended December 31, (in millions) 2017 2016 2015 Discount related to roaming expenses $ — $ (15 ) $ (21 ) Fees incurred for use of the T-Mobile brand 79 74 65 Expenses for telecommunications and IT services 12 25 23 International long distance agreement 55 60 — We have an agreement with Deutsche Telekom for the reimbursement of certain administrative expenses, which were $11 million , $11 million , and $2 million for the years ended December 31, 2017 , 2016 and 2015 , respectively.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Note 15 – Subsequent Events On January 1, 2018, we closed on a UPA to acquire the remaining equity in IWS, a 54% owned unconsolidated subsidiary, for a purchase price of $25 million . See Note 5 - Goodwill, Spectrum Licenses and Other Intangible Assets for further information. On January 22, 2018, we completed our acquisition of television innovator Layer3 TV for consideration of approximately $325 million , subject to customary working capital and other post-closing adjustments. See Note 13 - Commitments and Contingencies for further information. In January 2018, we redeemed $1.0 billion aggregate principal amount of our 6.125% Senior Notes due 2022 and issued $1.0 billion of public 4.500% Senior Notes due 2026 and issued $1.5 billion of public 4.750% Senior Notes due 2028. Additionally in January 2018, DT agreed to purchase $1.0 billion in aggregate principal amount of 4.500% Senior Notes due 2026 and $1.5 billion in aggregate principal amount of 4.750% Senior Notes due 2028 directly from T-Mobile USA and certain of its affiliates, as guarantors, with no underwriting discount. See Note 7 - Debt for further information. In February 2018, the service receivable sale arrangement was amended to extend the scheduled expiration date to March 2019. See Note 3 - Sales of Certain Receivables for further information. In February 2018, we extended the leases related to our corporate headquarters facility. See Note 13 - Commitments and Contingencies for further information. Through February 5, 2018, we made additional repurchases of our common stock. See Note 10 - Repurchases of Common Stock for further information.

Guarantor Financial Information

Guarantor Financial Information	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Guarantor Financial Information	Note 16 – Guarantor Financial Information Pursuant to the applicable indentures and supplemental indentures, the long-term debt to affiliates and third parties, excluding Senior Secured Term Loans and capital leases, issued by T-Mobile USA (“Issuer”) is fully and unconditionally guaranteed, jointly and severally, on a senior unsecured basis by T-Mobile (“Parent”) and certain of the Issuer’s 100% owned subsidiaries (“Guarantor Subsidiaries”). In January 2017, T-Mobile USA, and certain of its affiliates, as guarantors, borrowed $4.0 billion under the Incremental Term Loan Facility to refinance $1.98 billion of outstanding secured term loans under its Term Loan Credit Agreement dated November 9, 2015, with the remaining net proceeds from the transaction intended to be used to redeem callable high yield debt. In March 2017, T-Mobile USA and certain of its affiliates, as guarantors, (i) issued $500 million in aggregate principal amount of public 4.000% Senior Notes due 2022 , (ii) issued $500 million in aggregate principal amount of public 5.125% Senior Notes due 2025 and (iii) issued $500 million in aggregate principal amount of public 5.375% Senior Notes due 2027 . In April 2017, T-Mobile USA and certain of its affiliates, as guarantors, (i) issued $1.0 billion in aggregate principal amount of 4.000% Senior Notes due 2022 , (ii) issued $1.25 billion in aggregate principal amount of 5.125% Senior Notes due 2025 and (iii) issued $750 million in aggregate principal amount of 5.375% Senior Notes due 2027 . Additionally, T-Mobile USA and certain of its affiliates, as guarantors, redeemed through net settlement, the $1.25 billion outstanding aggregate principal amount of the 6.288% Senior Reset Notes to affiliates due 2019 and $1.25 billion in aggregate principal amount of the 6.366% Senior Reset Notes to affiliates due 2020. In May 2017, T-Mobile USA and certain of its affiliates, as guarantors, (i) issued $2.0 billion in aggregate principal amount of 5.300% Senior Notes due 2021 , (ii) issued $1.35 billion in aggregate principal amount of 6.000% Senior Notes due 2024 and (iii) issued $650 million in aggregate principal amount of 6.000% Senior Notes due 2024 . In September 2017, T-Mobile USA and certain of its affiliates, as guarantors, issued the remaining $500 million in aggregate principal amount of 5.375% Senior Notes due 2027 . See Note 7 - Debt for further information. The guarantees of the Guarantor Subsidiaries are subject to release in limited circumstances only upon the occurrence of certain customary conditions. The indentures and credit facilities governing the long-term debt contain covenants that, among other things, limit the ability of the Issuer and the Guarantor Subsidiaries to: incur more debt; pay dividends and make distributions; make certain investments; repurchase stock; create liens or other encumbrances; enter into transactions with affiliates; enter into transactions that restrict dividends or distributions from subsidiaries; and merge, consolidate, or sell, or otherwise dispose of, substantially all of their assets. Certain provisions of each of the credit facilities, indentures and supplemental indentures relating to the long-term debt restrict the ability of the Issuer to loan funds or make payments to Parent. However, the Issuer and Guarantor Subsidiaries are allowed to make certain permitted payments to the Parent under the terms of the indentures and the supplemental indentures. During the preparation of the condensed consolidating financial information of T-Mobile US, Inc. and Subsidiaries for the year ended December 31, 2017 , it was determined that certain intercompany advances were misclassified in Net cash provided by (used in) operating activities and Net cash (used in) provided by financing activities in the Condensed Consolidating Statement of Cash Flows Information for the years ended December 31, 2016 and 2015, as filed in our 2016 Form 10-K. We have revised the Issuer, Guarantor Subsidiaries and Non-Guarantor Subsidiaries columns of the Condensed Consolidating Statement of Cash Flows Information to reclassify Intercompany advances, net from Net cash provided by (used in) operating activities to Net cash (used in) provided by financing activities. The impacts to the Issuer, Guarantor Subsidiaries and Non-Guarantor Subsidiaries columns for the year ended December 31, 2016 were $696 million , $625 million and $71 million , respectively. The impacts to the Issuer, Guarantor Subsidiaries and Non-Guarantor Subsidiaries columns for the year ended December 31, 2015 were $3.4 billion , $3.3 billion and $69 million , respectively. The revisions, which we have determined are not material, are eliminated upon consolidation and have no impact on our consolidated cash flows. Presented below is the condensed consolidating financial information as of December 31, 2017 and December 31, 2016 , and for the years ended December 31, 2017 , 2016 , and 2015 . Condensed Consolidating Balance Sheet Information December 31, 2017 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Assets Current assets Cash and cash equivalents $ 74 $ 1 $ 1,086 $ 58 $ — $ 1,219 Accounts receivable, net — — 1,659 256 — 1,915 Equipment installment plan receivables, net — — 2,290 — — 2,290 Accounts receivable from affiliates — — 22 — — 22 Inventories — — 1,566 — — 1,566 Other current assets — — 1,275 628 — 1,903 Total current assets 74 1 7,898 942 — 8,915 Property and equipment, net (1) — — 21,890 306 — 22,196 Goodwill — — 1,683 — — 1,683 Spectrum licenses — — 35,366 — — 35,366 Other intangible assets, net — — 217 — — 217 Investments in subsidiaries, net 22,534 40,988 — — (63,522 ) — Intercompany receivables and note receivables — 8,503 — — (8,503 ) — Equipment installment plan receivables due after one year, net — — 1,274 — — 1,274 Other assets — 2 814 236 (140 ) 912 Total assets $ 22,608 $ 49,494 $ 69,142 $ 1,484 $ (72,165 ) $ 70,563 Liabilities and Stockholders' Equity Current liabilities Accounts payable and accrued liabilities $ — $ 253 $ 8,014 $ 261 $ — $ 8,528 Payables to affiliates — 146 36 — — 182 Short-term debt — 999 613 — — 1,612 Deferred revenue — — 779 — — 779 Other current liabilities 17 — 192 205 — 414 Total current liabilities 17 1,398 9,634 466 — 11,515 Long-term debt — 10,911 1,210 — — 12,121 Long-term debt to affiliates — 14,586 — — — 14,586 Tower obligations (1) — — 392 2,198 — 2,590 Deferred tax liabilities — — 3,677 — (140 ) 3,537 Deferred rent expense — — 2,720 — — 2,720 Negative carrying value of subsidiaries, net — — 629 — (629 ) — Intercompany payables and debt 32 — 8,201 270 (8,503 ) — Other long-term liabilities — 65 866 4 — 935 Total long-term liabilities 32 25,562 17,695 2,472 (9,272 ) 36,489 Total stockholders' equity (deficit) 22,559 22,534 41,813 (1,454 ) (62,893 ) 22,559 Total liabilities and stockholders' equity $ 22,608 $ 49,494 $ 69,142 $ 1,484 $ (72,165 ) $ 70,563 (1) Assets and liabilities for Non-Guarantor Subsidiaries are primarily included in VIEs related to the 2012 Tower Transaction. See Note 8 – Tower Obligations for further information. Condensed Consolidating Balance Sheet Information December 31, 2016 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Assets Current assets Cash and cash equivalents $ 358 $ 2,733 $ 2,342 $ 67 $ — $ 5,500 Accounts receivable, net — — 1,675 221 — 1,896 Equipment installment plan receivables, net — — 1,930 — — 1,930 Accounts receivable from affiliates — — 40 — — 40 Inventories — — 1,111 — — 1,111 Asset purchase deposit — — 2,203 — — 2,203 Other current assets — — 972 565 — 1,537 Total current assets 358 2,733 10,273 853 — 14,217 Property and equipment, net (1) — — 20,568 375 — 20,943 Goodwill — — 1,683 — — 1,683 Spectrum licenses — — 27,014 — — 27,014 Other intangible assets, net — — 376 — — 376 Investments in subsidiaries, net 17,682 35,095 — — (52,777 ) — Intercompany receivables and note receivables 196 6,826 — — (7,022 ) — Equipment installment plan receivables due after one year, net — — 984 — — 984 Other assets — 7 600 262 (195 ) 674 Total assets $ 18,236 $ 44,661 $ 61,498 $ 1,490 $ (59,994 ) $ 65,891 Liabilities and Stockholders' Equity Current liabilities Accounts payable and accrued liabilities $ — $ 423 $ 6,474 $ 255 $ — $ 7,152 Payables to affiliates — 79 46 — — 125 Short-term debt — 20 334 — — 354 Deferred revenue — — 986 — — 986 Other current liabilities — — 258 147 — 405 Total current liabilities — 522 8,098 402 — 9,022 Long-term debt — 20,741 1,091 — — 21,832 Long-term debt to affiliates — 5,600 — — — 5,600 Tower obligations (1) — — 400 2,221 — 2,621 Deferred tax liabilities — — 5,133 — (195 ) 4,938 Deferred rent expense — — 2,616 — — 2,616 Negative carrying value of subsidiaries, net — — 568 — (568 ) — Intercompany payables and debt — — 6,785 237 (7,022 ) — Other long-term liabilities — 116 906 4 — 1,026 Total long-term liabilities — 26,457 17,499 2,462 (7,785 ) 38,633 Total stockholders' equity (deficit) 18,236 17,682 35,901 (1,374 ) (52,209 ) 18,236 Total liabilities and stockholders' equity $ 18,236 $ 44,661 $ 61,498 $ 1,490 $ (59,994 ) $ 65,891 (1) Assets and liabilities for Non-Guarantor Subsidiaries are primarily included in VIEs related to the 2012 Tower Transaction. See Note 8 – Tower Obligations for further information. Condensed Consolidating Statement of Comprehensive Income Information Year Ended December 31, 2017 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Revenues Service revenues $ — $ — $ 28,894 $ 2,113 $ (847 ) $ 30,160 Equipment revenues — — 9,620 — (245 ) 9,375 Other revenues — 3 879 212 (25 ) 1,069 Total revenues — 3 39,393 2,325 (1,117 ) 40,604 Operating expenses Cost of services, exclusive of depreciation and amortization shown separately below — — 6,076 24 — 6,100 Cost of equipment sales — — 10,849 1,003 (244 ) 11,608 Selling, general and administrative — — 12,276 856 (873 ) 12,259 Depreciation and amortization — — 5,914 70 — 5,984 Gains on disposal of spectrum licenses — — (235 ) — — (235 ) Total operating expense — — 34,880 1,953 (1,117 ) 35,716 Operating income — 3 4,513 372 — 4,888 Other income (expense) Interest expense — (811 ) (109 ) (191 ) — (1,111 ) Interest expense to affiliates — (560 ) (23 ) — 23 (560 ) Interest income 1 29 10 — (23 ) 17 Other (expense) income, net — (88 ) 16 (1 ) — (73 ) Total other income (expense), net 1 (1,430 ) (106 ) (192 ) — (1,727 ) Income (loss) before income taxes 1 (1,427 ) 4,407 180 — 3,161 Income tax benefit (expense) — — 1,527 (152 ) — 1,375 Earnings (loss) of subsidiaries 4,535 5,962 (57 ) — (10,440 ) — Net income 4,536 4,535 5,877 28 (10,440 ) 4,536 Dividends on preferred stock (55 ) — — — — (55 ) Net income attributable to common stockholders $ 4,481 $ 4,535 $ 5,877 $ 28 $ (10,440 ) $ 4,481 Net Income $ 4,536 $ 4,535 $ 5,877 $ 28 $ (10,440 ) $ 4,536 Other comprehensive income, net of tax Other comprehensive income, net of tax 7 7 7 — (14 ) 7 Total comprehensive income $ 4,543 $ 4,542 $ 5,884 $ 28 $ (10,454 ) $ 4,543 Condensed Consolidating Statement of Comprehensive Income Information Year Ended December 31, 2016 (in millions) Parent Issuer Guarantor Subsidiaries (As adjusted - See Note 1 ) Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated (As adjusted - See Note 1 ) Revenues Service revenues $ — $ — $ 26,613 $ 2,023 $ (792 ) $ 27,844 Equipment revenues — — 9,145 — (418 ) 8,727 Other revenues — 3 739 (1) 195 (18 ) 919 Total revenues — 3 36,497 (1) 2,218 (1,228 ) 37,490 Operating expenses Cost of services, exclusive of depreciation and amortization shown separately below — — 5,707 24 — 5,731 Cost of equipment sales — — 10,209 1,027 (417 ) 10,819 Selling, general and administrative — — 11,321 868 (811 ) 11,378 Depreciation and amortization — — 6,165 78 — 6,243 Cost of MetroPCS business combination — — 104 — — 104 Gains on disposal of spectrum licenses — — (835 ) — — (835 ) Total operating expenses — — 32,671 1,997 (1,228 ) 33,440 Operating income — 3 3,826 (1) 221 — 4,050 Other income (expense) Interest expense — (1,147 ) (82 ) (189 ) — (1,418 ) Interest expense to affiliates — (312 ) — — — (312 ) Interest income (expense) — 31 (18 ) (1) — — 13 Other income (expense), net — 2 (8 ) — — (6 ) Total other expense, net — (1,426 ) (108 ) (1) (189 ) — (1,723 ) Income (loss) before income taxes — (1,423 ) 3,718 32 — 2,327 Income tax expense — — (857 ) (10 ) — (867 ) Earnings (loss) of subsidiaries 1,460 2,883 (17 ) — (4,326 ) — Net income 1,460 1,460 2,844 22 (4,326 ) 1,460 Dividends on preferred stock (55 ) — — — — (55 ) Net income attributable to common stockholders $ 1,405 $ 1,460 $ 2,844 $ 22 $ (4,326 ) $ 1,405 Net income $ 1,460 $ 1,460 $ 2,844 $ 22 $ (4,326 ) $ 1,460 Other comprehensive income, net of tax Other comprehensive income, net of tax 2 2 2 2 (6 ) 2 Total comprehensive income $ 1,462 $ 1,462 $ 2,846 $ 24 $ (4,332 ) $ 1,462 (1) The amortized imputed discount on EIP receivables previously recognized as Interest income has been retrospectively reclassified as Other revenues. See Note 1 - Summary of Significant Accounting Policies for further information. Condensed Consolidating Statement of Comprehensive Income Information Year Ended December 31, 2015 (in millions) Parent Issuer Guarantor Subsidiaries (As adjusted - See Note 1 ) Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated (As adjusted - See Note 1 ) Revenues Service revenues $ — $ — $ 23,748 $ 1,669 $ (596 ) $ 24,821 Equipment revenues — — 7,148 — (430 ) 6,718 Other revenues — 1 770 (1) 171 (14 ) 928 Total revenues — 1 31,666 (1) 1,840 (1,040 ) 32,467 Operating expenses Cost of services, exclusive of depreciation and amortization shown separately below — — 5,530 24 — 5,554 Cost of equipment sales — — 9,055 720 (431 ) 9,344 Selling, general and administrative — — 10,065 733 (609 ) 10,189 Depreciation and amortization — — 4,605 83 — 4,688 Cost of MetroPCS business combination — — 376 — — 376 Gains on disposal of spectrum licenses — — (163 ) — — (163 ) Total operating expenses — — 29,468 1,560 (1,040 ) 29,988 Operating income — 1 2,198 (1) 280 — 2,479 Other income (expense) Interest expense — (847 ) (50 ) (188 ) — (1,085 ) Interest expense to affiliates — (411 ) — — — (411 ) Interest income — 2 4 (1) — — 6 Other expense, net — (10 ) — (1 ) — (11 ) Total other expense, net — (1,266 ) (46 ) (1) (189 ) — (1,501 ) Income (loss) before income taxes — (1,265 ) 2,152 91 — 978 Income tax expense — — (214 ) (31 ) — (245 ) Earnings (loss) of subsidiaries 733 1,998 (48 ) — (2,683 ) — Net income 733 733 1,890 60 (2,683 ) 733 Dividends on preferred stock (55 ) — — — — (55 ) Net income attributable to common stockholders $ 678 $ 733 $ 1,890 $ 60 $ (2,683 ) $ 678 Net income $ 733 $ 733 $ 1,890 $ 60 $ (2,683 ) $ 733 Other comprehensive loss, net of tax Other comprehensive loss, net of tax (2 ) (2 ) (2 ) — 4 (2 ) Total comprehensive income $ 731 $ 731 $ 1,888 $ 60 $ (2,679 ) $ 731 (1) The amortized imputed discount on EIP receivables previously recognized as Interest income has been retrospectively reclassified as Other revenues. See Note 1 - Summary of Significant Accounting Policies for further information. Condensed Consolidating Statement of Cash Flows Information Year Ended December 31, 2017 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Operating activities Net cash provided by (used in) operating activities $ 1 $ (1,613 ) $ 9,616 $ 58 $ (100 ) $ 7,962 Investing activities Purchases of property and equipment — — (5,237 ) — — (5,237 ) Purchases of spectrum licenses and other intangible assets, including deposits — — (5,828 ) — — (5,828 ) Equity investment in subsidiary (308 ) — — — 308 — Other, net — — 1 — — 1 Net cash used in investing activities (308 ) — (11,064 ) — 308 (11,064 ) Financing activities Proceeds from issuance of long-term debt — 10,480 — — — 10,480 Proceeds from borrowing on revolving credit facility, net — 2,910 — — — 2,910 Repayments of revolving credit facility — — (2,910 ) — — (2,910 ) Repayments of capital lease obligations — — (486 ) — — (486 ) Repayments of short-term debt for purchases of inventory, property and equipment, net — — (300 ) — — (300 ) Repayments of long-term debt — — (10,230 ) — — (10,230 ) Proceeds from exercise of stock options 21 — — — — 21 Repurchases of common shares (427 ) — — — — (427 ) Intercompany advances, net 484 (14,817 ) 14,300 33 — — Equity investment from parent — 308 — — (308 ) — Tax withholdings on share-based awards — — (166 ) — — (166 ) Intercompany dividend paid — — — (100 ) 100 — Dividends on preferred stock (55 ) — — — — (55 ) Other, net — — (16 ) — — (16 ) Net cash provided by (used in) financing activities 23 (1,119 ) 192 (67 ) (208 ) (1,179 ) Change in cash and cash equivalents (284 ) (2,732 ) (1,256 ) (9 ) — (4,281 ) Cash and cash equivalents Beginning of period 358 2,733 2,342 67 — 5,500 End of period $ 74 $ 1 $ 1,086 $ 58 $ — $ 1,219 Condensed Consolidating Statement of Cash Flows Information Year Ended December 31, 2016 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Operating activities Net cash provided by (used in) operating activities $ 6 $ (1,335 ) $ 7,541 $ 33 $ (110 ) $ 6,135 Investing activities Purchases of property and equipment — — (4,702 ) — — (4,702 ) Purchases of spectrum licenses and other intangible assets, including deposits — — (3,968 ) — — (3,968 ) Sales of short-term investments — 2,000 998 — — 2,998 Other, net — — (8 ) — — (8 ) Net cash provided by (used in) investing activities — 2,000 (7,680 ) — — (5,680 ) Financing activities Proceeds from issuance of long-term debt — 997 — — — 997 Repayments of capital lease obligations — — (205 ) — — (205 ) Repayments of short-term debt for purchases of inventory, property and equipment, net — — (150 ) — — (150 ) Repayments of long-term debt — — (20 ) — — (20 ) Intercompany advances, net — (696 ) 625 71 — — Proceeds from exercise of stock options 29 — — — — 29 Tax withholdings on share-based awards — — (121 ) — — (121 ) Intercompany dividend paid — — — (110 ) 110 — Dividends on preferred stock (55 ) — — — — (55 ) Other, net — — (12 ) — — (12 ) Net cash (used in) provided by financing activities (26 ) 301 117 (39 ) 110 463 Change in cash and cash equivalents (20 ) 966 (22 ) (6 ) — 918 Cash and cash equivalents Beginning of period 378 1,767 2,364 73 — 4,582 End of period $ 358 $ 2,733 $ 2,342 $ 67 $ — $ 5,500 Condensed Consolidating Statement of Cash Flows Information Year Ended December 31, 2015 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Operating activities Net cash provided by (used in) operating activities $ (1 ) $ (1,147 ) $ 6,652 $ 85 $ (175 ) $ 5,414 Investing activities Purchases of property and equipment — — (4,724 ) — — (4,724 ) Purchases of spectrum licenses and other intangible assets, including deposits — — (1,935 ) — — (1,935 ) Purchases of short-term investments — (1,999 ) (998 ) — — (2,997 ) Investment in subsidiaries (1,905 ) — — — 1,905 — Other, net — — 96 — — 96 Net cash used in investing activities (1,905 ) (1,999 ) (7,561 ) — 1,905 (9,560 ) Financing activities Proceeds from capital contribution — 1,905 — — (1,905 ) — Proceeds from issuance of long-term debt — 3,979 — — — 3,979 Proceeds from tower obligations — 140 — — — 140 Repayments of capital lease obligations — — (57 ) — — (57 ) Repayments of short-term debt for purchases of inventory, property and equipment, net — — (564 ) — — (564 ) Intercompany advances, net — (3,357 ) 3,288 69 — — Proceeds from exercise of stock options 47 — — — — 47 Intercompany dividend paid — — — (175 ) 175 — Tax withholdings on share-based awards — — (156 ) — — (156 ) Dividends on preferred stock (41 ) — (14 ) — — (55 ) Other, net — — 79 — — 79 Net cash provided by (used in) financing activities 6 2,667 2,576 (106 ) (1,730 ) 3,413 Change in cash and cash equivalents (1,900 ) (479 ) 1,667 (21 ) — (733 ) Cash and cash equivalents Beginning of period 2,278 2,246 697 94 — 5,315 End of period $ 378 $ 1,767 $ 2,364 $ 73 $ — $ 4,582

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information [Abstract]
Quarterly Financial Information (Unaudited)	Supplementary Data Quarterly Financial Information (Unaudited) (in millions, except shares and per share amounts) First Quarter Second Quarter Third Quarter Fourth Quarter Full Year 2017 Total revenues $ 9,613 $ 10,213 $ 10,019 $ 10,759 $ 40,604 Operating income 1,037 1,416 1,323 1,112 4,888 Net income 698 581 550 2,707 4,536 Dividends on preferred stock (14 ) (14 ) (13 ) (14 ) (55 ) Net income attributable to common stockholders 684 567 537 2,693 4,481 Earnings per share Basic $ 0.83 $ 0.68 $ 0.65 $ 3.22 $ 5.39 Diluted 0.80 0.67 0.63 3.11 5.20 Weighted average shares outstanding Basic 827,723,034 830,971,528 831,189,779 837,416,683 831,850,073 Diluted 869,395,250 870,456,447 871,420,065 871,501,578 871,787,450 Net income includes: Gains on disposal of spectrum licenses $ (37 ) $ (1 ) $ (29 ) $ (168 ) $ (235 ) 2016 Total revenues (1) $ 8,664 $ 9,287 $ 9,305 $ 10,234 $ 37,490 Operating income (1) 1,168 833 1,048 1,001 4,050 Net income 479 225 366 390 1,460 Dividends on preferred stock (14 ) (14 ) (13 ) (14 ) (55 ) Net income attributable to common stockholders 465 211 353 376 1,405 Earnings per share Basic $ 0.57 $ 0.26 $ 0.43 $ 0.46 $ 1.71 Diluted 0.56 0.25 0.42 0.45 1.69 Weighted average shares outstanding Basic 819,431,761 822,434,490 822,998,697 824,982,734 822,470,275 Diluted 859,382,827 829,752,956 832,257,819 867,262,400 833,054,545 Net income includes: Cost of MetroPCS business combination $ 36 $ 59 $ 15 $ (6 ) $ 104 Gains on disposal of spectrum licenses (636 ) — (199 ) — (835 ) (1) The amortized imputed discount on EIP receivables previously recognized as Interest income has been retrospectively re-classified as Other revenues. See Note 1 - Summary of Significant Accounting Policies of the Notes to the Consolidated Financial Statements included in Part II, Item 8 of this Form 10-K for further information. Earnings per share is computed independently for each quarter and the sum of the quarters may not equal earnings per share for the full year.

Summary of Significant Accoun26

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business T-Mobile US, Inc. (“T-Mobile,” “we,” “our,” “us” or the “Company”), together with its consolidated subsidiaries, is a leading provider of mobile communications services, including voice, messaging and data, under its flagship brands, T-Mobile and MetroPCS, in the United States (“U.S.”), Puerto Rico and the U.S. Virgin Islands. We provide mobile communications services primarily using 4G Long-Term Evolution (“LTE”) technology. We also offer a wide selection of wireless devices, including handsets, tablets and other mobile communication devices, and accessories for sale, as well as financing through Equipment Installment Plans (“EIP”) and leasing through JUMP! On Demand™. Additionally, we provide reinsurance for handset insurance policies and extended warranty contracts offered to our mobile communications customers.
Basis of Presentation	Basis of Presentation The consolidated financial statements include the balances and results of operations of T-Mobile and our consolidated subsidiaries. We operate as a single operating segment. We consolidate majority-owned subsidiaries over which we exercise control, as well as variable interest entities (“VIE”) where we are deemed to be the primary beneficiary and VIEs, which cannot be deconsolidated, such as those related to Tower obligations. Intercompany transactions and balances have been eliminated in consolidation.
Reclassification	Certain prior year amounts have been reclassified, such as those relating to the imputed discount on EIP receivables reclassified from Interest income to Other revenues in our Consolidated Statements of Comprehensive Income , to conform to the current year’s presentation. See “Change in Accounting Principle” below.
Use of Estimates	The preparation of financial statements in conformity with U.S. generally accepted accounting principles (“GAAP”) requires our management to make estimates and assumptions which affect the financial statements and accompanying notes. Examples include service revenues earned but not yet billed, service revenues billed but not yet earned, relative selling prices, allowances for credit losses and sales returns, discounts for imputed interest on EIP receivables, guarantee liabilities, losses incurred but not yet reported, tax liabilities, deferred income taxes including valuation allowances, useful lives of long-lived assets, cost estimates of asset retirement obligations, residual values on leased handsets, reasonably assured renewal terms for operating leases, stock-based compensation forfeiture rates, and fair value measurements, including those related to goodwill, spectrum licenses, intangible assets, beneficial interests in factoring and securitization transactions and derivative financial instruments. Estimates are based on historical experience, where applicable, and other assumptions which our management believes are reasonable under the circumstances. These estimates are inherently subject to judgment and actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents consist of highly liquid money market funds and U.S. Treasury securities with remaining maturities of three months or less at the date of purchase.
Receivables and Allowance for Credit Losses	Receivables and Allowance for Credit Losses Accounts receivable consist primarily of amounts currently due from customers, other carriers and third-party retail channels. Accounts receivable not held for sale are reported in the balance sheet at outstanding principal adjusted for any charge-offs and the allowance for credit losses. Accounts receivable held for sale are reported at the lower of amortized cost or fair value. We have an arrangement to sell the majority of service accounts receivable on a revolving basis, which are treated as sales of financial assets. We offer certain retail customers the option to pay for their devices and other purchases in installments over a period of up to 24 months using an EIP. EIP receivables not held for sale are reported in the balance sheet at outstanding principal adjusted for any charge-offs, allowance for credit losses and unamortized discounts. Receivables held for sale are reported at the lower of amortized cost or fair value. At the time of an installment sale, we impute a discount for interest as there is no stated rate of interest on the EIP receivables and record the EIP receivables at their present value, which is determined by discounting future payments at the imputed interest rate. The difference between the present value of the EIP receivables and their face amount results in a discount which is recorded as a direct reduction to the carrying value with a corresponding reduction to equipment revenues in our Consolidated Statements of Comprehensive Income . We determine the imputed discount rate based primarily on current market interest rates and the estimated credit risk on the EIP receivables. As a result, we do not recognize a separate valuation allowance at the time of issuance as the effects of uncertainty about future cash flows are included in the initial present value measurement of the receivable. The imputed discount on EIP receivables is amortized over the financed installment term using the effective interest method and recognized as Other revenues in our Consolidated Statements of Comprehensive Income . Subsequent to the initial determination of the imputed discount, we assess the need for and, if necessary, recognize an allowance for credit losses to the extent the amount of estimated probable losses on the gross EIP receivable balances exceed the remaining unamortized imputed discount balances. The current portion of the EIP receivables is included in Equipment installment plan receivables, net and the long-term portion of the EIP receivables is included in Equipment installment plan receivables due after one year, net in our Consolidated Balance Sheets . We have an arrangement to sell certain EIP receivables on a revolving basis, which are treated as sales of financial assets. We maintain an allowance for credit losses and determine its appropriateness through an established process that assesses the losses inherent in our receivables portfolio. We develop and document our allowance methodology at the portfolio segment level - accounts receivable portfolio and EIP receivable portfolio segments. While we attribute portions of the allowance to our respective accounts receivable and EIP portfolio segments, the entire allowance is available to absorb credit losses inherent in the total receivables portfolio. Our process involves procedures to appropriately consider the unique risk characteristics of our accounts receivable and EIP receivable portfolio segments. For each portfolio segment, losses are estimated collectively for groups of receivables with similar characteristics. Our allowance levels are influenced by receivable volumes, receivable delinquency status, historical loss experience and other conditions influencing loss expectations, such as macro-economic conditions.
Inventories	Inventories Inventories consist primarily of wireless devices and accessories, which are valued at the lower of cost or market. Cost is determined using standard cost which approximates average cost. Shipping and handling costs paid to wireless device and accessories vendors, and costs to refurbish used devices recovered through our device upgrade programs are included in the standard cost of inventory. We record inventory write-downs to net realizable value for obsolete and slow-moving items based on inventory turnover trends and historical experience.
Long-Lived Assets	Long-Lived Assets Long-lived assets include assets that do not have indefinite lives, such as property and equipment and other intangible assets. We assess potential impairments to our long-lived assets when events or changes in circumstances indicate the carrying amount of the asset may not be recoverable. If any indicators of impairment are present, we test recoverability. The carrying value of a long-lived asset or asset group is not recoverable if it exceeds the sum of the undiscounted cash flows expected to be generated from the use and eventual disposition of the asset or asset group. If the undiscounted cash flows do not exceed the asset or asset group’s carrying amount, then an impairment loss is recorded, measured as the amount by which the carrying amount of a long-lived asset or asset group exceeds its fair value. Property and Equipment Property and equipment consists of buildings and equipment, wireless communication systems, leasehold improvements, capitalized software, leased wireless devices and construction in progress. Buildings and equipment include certain network server equipment. Wireless communication systems include assets to operate our wireless network and IT data centers, including tower assets and leasehold improvements, assets related to the liability for the retirement of long-lived assets and capital leases. Leasehold improvements include asset improvements other than those related to the wireless network. Property and equipment are recorded at cost less accumulated depreciation and impairments, if any, in Property and equipment, net on our Consolidated Balance Sheets . We generally depreciate property and equipment over the period the property and equipment provide economic benefit. Depreciable life studies are performed periodically to confirm the appropriateness of useful lives for certain categories of property and equipment. These studies take into account actual usage, physical wear and tear, replacement history and assumptions about technology evolution. When these factors indicate the useful life of an asset is different from the previous assessment, the remaining book value is depreciated prospectively over the adjusted remaining estimated useful life. Leasehold improvements are depreciated over the shorter of their estimated useful lives or the related lease term. We introduced JUMP! On Demand, which allows customers to lease a device over a period of up to 18 months and upgrade it for a new device up to one time per month. To date, all of our leased devices were classified as operating leases. At operating lease inception, leased wireless devices are transferred from inventory to property and equipment. Leased wireless devices are depreciated to their estimated residual value over the period expected to provide utility to us, which is generally shorter than the lease term and considers expected losses. Revenues associated with the leased wireless devices, net of incentives, are generally recognized over the lease term. Upon device upgrade or at lease end, customers must return or purchase their device. Returned devices transferred from Property and equipment, net are recorded as inventory and are valued at the lower of cost or market with any write-down to market recognized as Cost of equipment sales in our Consolidated Statements of Comprehensive Income . Costs of major replacements and improvements are capitalized. Repair and maintenance expenditures which do not enhance or extend the asset’s useful life are charged to operating expenses as incurred. Construction costs, labor and overhead incurred in the expansion or enhancement of our wireless network are capitalized. Capitalization commences with pre-construction period administrative and technical activities, which includes obtaining leases, zoning approvals and building permits, and ceases at the point at which the asset is ready for its intended use. We capitalize interest associated with the acquisition or construction of certain property and equipment. Capitalized interest is reported as a reduction in interest expense and depreciated over the useful life of the related assets. Future obligations related to capital leases are included in Short-term debt and Long-term debt in our Consolidated Balance Sheets . Depreciation of assets held under capital leases is included in Depreciation and amortization expense in our Consolidated Statements of Comprehensive Income .
Asset Retirement Obligations	We record an asset retirement obligation for the fair value of legal obligations associated with the retirement of tangible long-lived assets and a corresponding increase in the carrying amount of the related asset in the period in which the obligation is incurred. In periods subsequent to initial measurement, we recognize changes in the liability resulting from the passage of time and revisions to either the timing or the amount of the original estimate. Over time, the liability is accreted to its present value and the capitalized cost is depreciated over the estimated useful life of the asset. Our obligations relate primarily to certain legal obligations to remediate leased property on which our network infrastructure and administrative assets are located.
Software Capitalization	We capitalize certain costs incurred in connection with developing or acquiring internal use software. Capitalization of software costs commences once the final selection of the specific software solution has been made and management authorizes and commits to funding the software project. Capitalized software costs are included in Property and equipment, net in our Consolidated Balance Sheets and are amortized on a straight-line basis over the estimated useful life of the asset. Costs incurred during the preliminary project stage, as well as maintenance and training costs, are expensed as incurred.
Other Intangible Assets	Other Intangible Assets Intangible assets that do not have indefinite useful lives are amortized over their estimated useful lives. Customer lists are amortized using the sum-of-the-years-digits method over the expected period in which the relationship is expected to contribute to future cash flows. The remaining finite-lived intangible assets are amortized using the straight-line method.
Goodwill	Goodwill Goodwill consists of the excess of the purchase price over the fair value of identifiable net assets acquired in a business combination.
Spectrum Licenses	Spectrum Licenses Spectrum licenses are carried at costs incurred to acquire the spectrum licenses and the costs to prepare the spectrum licenses for their intended use, such as costs to clear acquired spectrum licenses. The Federal Communications Commission (“FCC”) issues spectrum licenses which provide us with the exclusive right to utilize designated radio frequency spectrum within specific geographic service areas to provide wireless communication services. While spectrum licenses are issued for a fixed period of time, typically for up to fifteen years, the FCC has granted license renewals routinely and at a nominal cost. The spectrum licenses held by us expire at various dates. We believe we will be able to meet all requirements necessary to secure renewal of our spectrum licenses at nominal costs. Moreover, we determined there are currently no legal, regulatory, contractual, competitive, economic or other factors that limit the useful lives of our spectrum licenses. Therefore, we determined the spectrum licenses should be treated as indefinite-lived intangible assets. At times, we enter into agreements to sell or exchange spectrum licenses. Upon entering into the arrangement, if the transaction has been deemed to have commercial substance, spectrum licenses are reviewed for impairment and transferred at their carrying value, net of any impairment, to assets held for sale included in Other current assets in our Consolidated Balance Sheets until approval and completion of the exchange or sale. Upon closing of the transaction, spectrum licenses acquired as part of an exchange of nonmonetary assets are valued at fair value and the difference between the fair value of the spectrum licenses obtained, book value of the spectrum licenses transferred and cash paid, if any, is recognized as a gain and included in Gains on disposal of spectrum licenses in our Consolidated Statements of Comprehensive Income . Our fair value estimates of spectrum licenses are based on information for which there is little or no observable market data. If the transaction lacks commercial substance or the fair value is not measurable, the acquired spectrum licenses are recorded at the book value of the assets transferred or exchanged.
Impairment	Impairment We assess the carrying value of our goodwill and other indefinite-lived intangible assets, such as our spectrum licenses, for potential impairment annually as of December 31, or more frequently if events or changes in circumstances indicate such assets might be impaired. When assessing goodwill for impairment we may elect to first perform a qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. If we do not perform a qualitative assessment, or if the qualitative assessment indicates it is more likely than not the fair value of the single reporting unit is less than its carrying amount, we perform a quantitative test. We recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized would not exceed the total amount of goodwill allocated to that reporting unit. We test our spectrum licenses for impairment on an aggregate basis, consistent with our management of the overall business at a national level. We may elect to first perform a qualitative assessment to determine whether it is more likely than not that the fair value of an intangible asset is less than its carrying value. If we do not perform the qualitative assessment, or if the qualitative assessment indicates it is more likely than not the fair value of the intangible asset is less than its carrying amount, we calculate the estimated fair value of the intangible asset. If the estimated fair value of the spectrum licenses is lower than their carrying amount, an impairment loss is recognized for the difference. We estimate fair value using the Greenfield methodology, which is an income approach, to estimate the price at which an orderly transaction to sell the asset would take place between market participants at the measurement date under current market conditions.
Guarantee Liabilities	Guarantee Liabilities We offer a device trade-in program, Just Upgrade My Phone (“JUMP!”), which provides eligible customers a specified-price trade-in right to upgrade their device. Upon enrollment, participating customers must finance the purchase of a device on an EIP and have a qualifying T-Mobile monthly wireless service plan, which is treated as a single multiple-element arrangement when entered into at or near the same time. Upon a qualifying JUMP! program upgrade, the customer’s remaining EIP balance is settled provided they trade-in their eligible used device in good working condition and purchase a new device from us on a new EIP. For customers who enroll in JUMP!, we recognize a liability and reduce revenue for the portion of revenue which represents the estimated fair value of the specified-price trade-in right guarantee. The guarantee liability is valued based on various economic and customer behavioral assumptions, which requires judgment, including estimating the customer's remaining EIP balance at trade-in, the expected fair value of the used device at trade-in, and the probability and timing of trade-in. We assess our guarantee liability at each reporting date to determine if facts and circumstances would indicate the incurrence of an incremental contingent liability is probable and if so, reasonably estimable. The recognition and subsequent adjustments of the contingent guarantee liability as a result of these assessments are recorded as adjustments to revenue. When customers upgrade their device, the difference between the EIP balance credit to the customer and the fair value of the returned device is recorded against the guarantee liabilities.
Fair Value Measurements	Fair Value Measurements We carry certain assets and liabilities at fair value. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The three-tier hierarchy for inputs used in measuring fair value, which prioritizes the inputs based on the observability as of the measurement date, is as follows: Level 1 Quoted prices in active markets for identical assets or liabilities; Level 2 Observable inputs other than the quoted prices in active markets for identical assets and liabilities; and Level 3 Unobservable inputs for which there is little or no market data, which require us to develop assumptions of what market participants would use in pricing the asset or liability. Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement requires judgment, and may affect the placement of assets and liabilities being measured within the fair value hierarchy. The carrying values of cash and cash equivalents, short-term investments, accounts receivable, accounts receivable from affiliates and accounts payable approximate fair value due to the short-term maturities of these instruments. The carrying values of EIP receivables approximate fair value as the receivables are recorded at their present value, net of unamortized discount and allowance for credit losses. There were no financial instruments with a carrying value materially different from their fair value, based on quoted market prices or rates for the same or similar instruments, or internal valuation models.
Derivative Financial Instruments	Derivative Financial Instruments Derivative financial instruments primarily relate to embedded derivatives for certain components of the reset feature of the Senior Reset Notes to affiliates, which are required to be bifurcated and are recorded on the Consolidated Balance Sheets at fair value. Changes in fair value are recognized in Interest expense to affiliates in our Consolidated Statements of Comprehensive Income . We do not enter into derivative positions for trading or speculative purposes.
Revenue Recognition	Revenue Recognition We primarily generate our revenue from providing wireless services to customers and selling or leasing devices and accessories. We offer our wireless services and devices to customers, which may be comprised of multiple contracts entered into with a customer at or near the same time. In recognizing revenue, we assess such agreements as a single bundled arrangement that may involve multiple deliverables, which include wireless services, wireless devices or a combination thereof, and allocate revenue between each deliverable based on the relative selling prices of each deliverable on a standalone basis. Wireless Services Revenue We generate our wireless service revenues from providing access to, and usage of, our wireless communications network. Service revenues also include revenues earned for providing value added services to customers, such as handset insurance services. Service revenues are billed either in advance or arrears or are prepaid and are recognized when the service is rendered and all other revenue recognition criteria have been met. Revenues that are not reasonably assured to be collectible are recorded on a cash basis as payments are received. The recognition of prepaid revenue is deferred until services are rendered or the customer’s rights to service expire unused. Generally, incentives given to customers are recorded as a reduction to revenue. We recognize service revenues for Data Stash plans when such services are delivered and the data is consumed, or at time of forfeiture or expiration. Revenues relating to unused data that is carried over to the following month are deferred and valued based on their relative standalone selling price. Revenue is recorded gross for arrangements involving the resale of third-party services where we are considered the primary obligor and is recorded net of associated costs incurred for services whereby we are not considered the primary obligor. Federal Universal Service Fund (“USF”) and other fees are assessed by various governmental authorities in connection with the services we provide to our customers. When we separately bill and collect these regulatory fees from customers, they are recorded gross in Total service revenues and cost of services in our Consolidated Statements of Comprehensive Income . For the years ended December 31, 2017 , 2016 and 2015 , we recorded approximately $258 million , $409 million and $334 million , respectively, of USF fees on a gross basis. Equipment Revenues We generate equipment revenues from the sale or lease of mobile communication devices and accessories. Device and accessory sales revenues are generally recognized when the products are delivered to, and accepted by, the customer or dealer. We defer a portion of equipment revenues and cost of equipment sales for expected device returns based on historical experience. We offer certain customers the option to pay for devices and accessories in installments using an EIP. Equipment sales not reasonably assured to be collectible are recorded on a cash basis as payments are received. In addition, for customers enrolled in JUMP!, we separate the JUMP! trade-in right from the multiple element arrangement at its fair value and defer the portion of revenue which represents the fair value of the trade-in right. See Guarantee Liabilities section above for further information. We introduced JUMP! On Demand, which allows customers to lease a device and upgrade their leased wireless device for a new device up to one time per month. Leased wireless devices are accounted for as operating leases and lease revenues are recognized as earned on a straight-line basis over the lease term. The residual value of purchased leased devices is recorded as equipment revenues and cost of equipment sales. See Property and Equipment section above for further information.
Rent Expense	Rent Expense We have operating leases for cell sites, retail locations, corporate offices and dedicated transportation lines, some of which have escalating rentals during the initial lease term and during subsequent optional renewal periods. We recognize rent expense on a straight-line basis, over the non-cancelable lease term and renewal periods that are considered reasonably assured at the inception of the lease. We consider several factors in assessing whether renewal periods are reasonably assured of being exercised, including the continued maturation of our network nationwide, technological advances within the telecommunications industry and the availability of alternative sites.
Advertising Expense	Advertising Expense We expense the cost of advertising and other promotional expenditures to market our services and products as incurred. For the years ended December 31, 2017 , 2016 and 2015 , advertising expenses included in Selling, general and administrative expenses in our Consolidated Statements of Comprehensive Income were $1.8 billion , $1.7 billion and $1.6 billion , respectively.
Income Taxes	Income Taxes Deferred tax assets and liabilities are recognized based on temporary differences between the financial statement and tax bases of assets and liabilities using enacted tax rates expected to be in effect when these differences are realized. A valuation allowance is recorded when it is more likely than not that some portion or all of a deferred tax asset will not be realized. The ultimate realization of a deferred tax asset depends on the ability to generate sufficient taxable income of the appropriate character and in the appropriate taxing jurisdictions within the carryforward periods available. We account for uncertainty in income taxes recognized in the financial statements in accordance with the accounting guidance for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. We assess whether it is more likely than not that a tax position will be sustained upon examination based on the technical merits of the position and adjust the unrecognized tax benefits in light of changes in facts and circumstances, such as changes in tax law, interactions with taxing authorities and developments in case law.
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Other comprehensive income (loss) consists of adjustments, net of tax, related to unrealized gains (losses) on available-for-sale securities. This is reported in Accumulated other comprehensive income as a separate component of stockholders’ equity until realized in earnings.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation cost for stock awards, which include restricted stock units (“RSUs”) and performance-based restricted stock units (“PRSUs”), is measured at fair value on the grant date and recognized as expense, net of expected forfeitures, over the related service period. The fair value of stock awards is based on the closing price of our common stock on the date of grant. RSUs are recognized as expense using the straight-line method. PRSUs are recognized as expense following a graded vesting schedule.
Earnings Per Share	Earnings Per Share Basic earnings per share is computed by dividing Net income attributable to common stockholders by the weighted-average number of common shares outstanding for the period. Diluted earnings per share is computed by giving effect to all potentially dilutive common shares outstanding during the period. Potentially dilutive common shares consist of outstanding stock options, RSUs and PRSUs, calculated using the treasury stock method, and prior to the conversion of our preferred stock, potentially dilutive common shares included mandatory convertible preferred stock calculated using the if-converted method. See Note 12 - Earnings Per Share for further information. Our Board of Directors authorized a share repurchase program during the fourth quarter of 2017. Repurchased shares are retired and reduce the number of shares issued and outstanding. See Note 10 - Repurchases of Common Stock for further information.
Variable Interest Entities	Variable Interest Entities VIEs are entities which lack sufficient equity to permit the entity to finance its activities without additional subordinated financial support from other parties, have equity investors which do not have the ability to make significant decisions relating to the entity's operations through voting rights, do not have the obligation to absorb the expected losses or do not have the right to receive the residual returns of the entity. The most common type of VIE is a special purpose entity (“SPE”). SPEs are commonly used in securitization transactions in order to isolate certain assets and distribute the cash flows from those assets to investors. SPEs are generally structured to insulate investors from claims on the SPE's assets by creditors of other entities, including the creditors of the seller of the assets. The primary beneficiary is required to consolidate the assets and liabilities of the VIE. The primary beneficiary is the party which has both the power to direct the activities of an entity that most significantly impact the VIE's economic performance, and through its interests in the VIE, the obligation to absorb losses or the right to receive benefits from the VIE which could potentially be significant to the VIE. We consolidate VIEs when we are deemed to be the primary beneficiary or when the VIE cannot be deconsolidated. In assessing which party is the primary beneficiary, all the facts and circumstances are considered, including each party’s role in establishing the VIE and its ongoing rights and responsibilities. This assessment includes, first, identifying the activities that most significantly impact the VIE’s economic performance; and second, identifying which party, if any, has power over those activities. In general, the parties that make the most significant decisions affecting the VIE (such as asset managers and servicers) or have the right to unilaterally remove those decision-makers are deemed to have the power to direct the activities of a VIE.
Accounting Pronouncements Adopted During the Current Year and Accounting Pronouncements Not Yet Adopted	Accounting Pronouncements Adopted During the Current Year In January 2017, the FASB issued ASU 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” The amendments in this update eliminate the requirement to perform step two of the goodwill impairment test, which requires a hypothetical purchase price allocation consistent with the principles in determining fair values of assets acquired and liabilities assumed in a business combination, when an impairment is determined to have occurred. Instead, if the carrying amount of a reporting unit exceeds its fair value, an impairment loss is recognized in an amount equal to that excess, limited by the amount of goodwill in that reporting unit. We adopted this new guidance in the fourth quarter of 2017. The implementation of this standard did not have an impact on our consolidated financial statements . Accounting Pronouncements Not Yet Adopted In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606)” (“ASU 2014-09”), and has since modified the standard with several ASUs. The standard is effective for us, and we adopted the standard, on January 1, 2018. The standard requires entities to recognize revenue through the application of a five-step model, which includes: identification of the contract; identification of the performance obligations; determination of the transaction price; allocation of the transaction price to the performance obligations; and recognition of revenue as the entity satisfies the performance obligations. The guidance permits two methods of adoption, the full retrospective method applying the standard to each prior reporting period presented, or the modified retrospective method with a cumulative effect of initially applying the guidance recognized at the date of initial application. The standard also allows entities to apply certain practical expedients at their discretion. We will adopt the standard using the modified retrospective method with a cumulative catch up adjustment and will provide additional disclosures comparing results to previous GAAP in our 2018 consolidated financial statements . We plan to apply the new revenue standard only to contracts not completed as of the date of initial application, referred to as open contracts. The most significant judgments and impacts upon adoption of the standard include the following items: • Upon adoption, we will defer (i.e. capitalize) incremental contract acquisition costs and recognize (i.e. amortize) them over the term of the initial contract and anticipated renewal contracts to which the costs relate. Deferred contract costs have an average amortization period of approximately 24 months, subject to being monitored every period to reflect any significant change in assumptions. In addition, the deferred contract cost asset is assessed for impairment on a periodic basis. We are utilizing the practical expedient permitting expensing of costs to obtain a contract when the expected amortization period is one year or less which typically results in expensing commissions paid to acquire branded prepaid service contracts. As a result, incremental contract acquisition costs paid on open contracts of approximately $150 million are expected to be capitalized and subsequently amortized upon adoption on January 1, 2018 as a cumulative effect adjustment to equity, which consists primarily of commissions paid to acquire branded postpaid service contracts. Contract costs capitalized for new contracts will accumulate during 2018 as deferred assets. As a result, we expect there to be a net benefit to operating income during 2018. As capitalized costs amortize into expense over time the accretive benefit to operating income anticipated in 2018 is expected to moderate in 2019 and become insignificant in 2020 as the timing benefits of deferring these costs dissipate. • Under the new standard, certain commissions paid to dealers previously recognized as a reduction to revenues will be recorded as commission costs in Selling, general and administrative expense. During 2017 such commission costs were approximately $425 million . • Promotional bill credits offered to customers on equipment sales that are paid over time and are contingent on the customer maintaining a service contract results in an extended service contract term with multiple performance obligations, which impacts the allocation and timing of revenue recognition between service revenue and equipment revenue. A contract asset will be recorded when control of the equipment transfers to the customer, and subsequently recognized as a reduction to service revenue over the extended contract term. Contract assets of approximately $140 million are expected to be capitalized upon adoption on January 1, 2018 as a cumulative effect adjustment. • We are recognizing the financing component in our EIP contracts, including those financing components that are not considered to be significant to the contract. This application is consistent with our current practice of imputing interest. We have implemented significant new revenue accounting systems, processes and internal controls over revenue recognition to assist us in the application of the new standard. The cumulative effect of initially applying the new revenue standard on January 1, 2018 is estimated to be a decrease to Accumulated deficit of approximately $220 million . In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842).” The standard requires all lessees to report a right-of-use asset and a lease liability for most leases. The income statement recognition is similar to existing lease accounting and is based on lease classification. The standard requires lessees and lessors to classify most leases using principles similar to existing lease accounting. For lessors, the standard modifies the classification criteria and the accounting for sales-type and direct financing leases. We are currently evaluating the standard, which will require recognizing and measuring leases at the beginning of the earliest period presented using a modified retrospective approach. Our evaluation includes assessing which of our arrangements qualify as a lease, and aggregating lease data and related information as well as determining whether previous conclusions for certain transactions, such as failed sale leaseback arrangements under Topic 840, would change under Topic 842. We plan to adopt the standard when it becomes effective for us beginning January 1, 2019, and expect the adoption of the standard will result in the recognition of right-of-use assets and lease liabilities that have not previously been recorded, which will have a material impact on our consolidated financial statements . We are in the process of implementing significant new lease accounting systems, processes and internal controls over lease recognition which will ultimately assist in the application of the new standard. In June 2016, the FASB issued ASU 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” The standard requires a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. The measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions and reasonable and supportable forecasts that affect the collectibility of the reported amount. The standard will become effective for us beginning January 1, 2020, and will require a cumulative-effect adjustment to Accumulated deficit as of the beginning of the first reporting period in which the guidance is effective (that is, a modified-retrospective approach). Early adoption is permitted for us as of January 1, 2019. We are currently evaluating the impact this guidance will have on our consolidated financial statements and the timing of adoption. In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments.” The standard is intended to reduce current diversity in practice and provides guidance on how certain cash receipts and payments are presented and classified in the statement of cash flows. The standard is effective for us, and we adopted the standard, on January 1, 2018. The standard will require a retrospective approach. The standard will impact the presentation of cash flows related to beneficial interests in securitization transactions, which is the deferred purchase price, resulting in a reclassification of cash inflows from Operating activities to Investing activities of approximately $4.3 billion and $3.5 billion for the years ended December 31, 2017 and 2016 , respectively, in our Consolidated Statements of Cash Flows . The standard will also impact the presentation of cash payments for debt prepayment or debt extinguishment costs, resulting in a reclassification of cash outflows from Operating activities to Financing activities of $188 million for the year ended December 31, 2017 , in our consolidated financial statements . In October 2016, the FASB issued ASU 2016-16, “Accounting for Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory.” The standard requires that the income tax impact of intra-entity sales and transfers of property, except for inventory, be recognized when the transfer occurs. The standard will become effective for us beginning January 1, 2018, and will require any deferred taxes not yet recognized on intra-entity transfers to be recorded to retained earnings under a modified retrospective approach. The implementation of this standard is not expected to have a material impact on our consolidated financial statements .

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	We have applied this change retrospectively and presented the effect on the years ended December 31, 2017 , 2016 and 2015 , in the tables below: Year Ended December 31, 2017 (in millions) Unadjusted Change in Accounting Principle As Adjusted Other revenues $ 789 $ 280 $ 1,069 Total revenues 40,324 280 40,604 Operating income 4,608 280 4,888 Interest income 297 (280 ) 17 Total other expense, net (1,447 ) (280 ) (1,727 ) Net income 4,536 — 4,536 Year Ended December 31, 2016 (in millions) As Filed Change in Accounting Principle As Adjusted Other revenues $ 671 $ 248 $ 919 Total revenues 37,242 248 37,490 Operating income 3,802 248 4,050 Interest income 261 (248 ) 13 Total other expense, net (1,475 ) (248 ) (1,723 ) Net income 1,460 — 1,460 Year Ended December 31, 2015 (in millions) As Filed Change in Accounting Principle As Adjusted Other revenues $ 514 $ 414 $ 928 Total revenues 32,053 414 32,467 Operating income 2,065 414 2,479 Interest income 420 (414 ) 6 Total other expense, net (1,087 ) (414 ) (1,501 ) Net income 733 — 733

Receivables and Allowance for28

Receivables and Allowance for Credit Losses (Tables)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Schedule of Equipment Installment Plan Receivables	The following table summarizes the EIP receivables, including imputed discounts and related allowance for credit losses: (in millions) December 31, December 31, EIP receivables, gross $ 3,960 $ 3,230 Unamortized imputed discount (264 ) (195 ) EIP receivables, net of unamortized imputed discount 3,696 3,035 Allowance for credit losses (132 ) (121 ) EIP receivables, net $ 3,564 $ 2,914 Classified on the balance sheet as: Equipment installment plan receivables, net $ 2,290 $ 1,930 Equipment installment plan receivables due after one year, net 1,274 984 EIP receivables, net $ 3,564 $ 2,914
Schedule of Unamortized Imputed Discount and Allowance for Credit Losses for Equipment Installment Plan Receivables	Activity for the years ended December 31, 2017 , 2016 , and 2015 , in the allowance for credit losses and unamortized imputed discount balances for the accounts receivable and EIP receivable segments were as follows: December 31, 2017 December 31, 2016 December 31, 2015 (in millions) Accounts Receivable Allowance EIP Receivables Allowance Total Accounts Receivable Allowance EIP Receivables Allowance Total Accounts Receivable Allowance EIP Receivables Allowance Total Allowance for credit losses and imputed discount, beginning of period $ 102 $ 316 $ 418 $ 116 $ 333 $ 449 $ 83 $ 448 $ 531 Bad debt expense 104 284 388 227 250 477 182 365 547 Write-offs, net of recoveries (120 ) (273 ) (393 ) (241 ) (277 ) (518 ) (149 ) (333 ) (482 ) Change in imputed discount on short-term and long-term EIP receivables N/A 252 252 N/A 186 186 N/A (84 ) (84 ) Impact on the imputed discount from sales of EIP receivables N/A (183 ) (183 ) N/A (176 ) (176 ) N/A (63 ) (63 ) Allowance for credit losses and imputed discount, end of period $ 86 $ 396 $ 482 $ 102 $ 316 $ 418 $ 116 $ 333 $ 449
Schedule of Equipment Installment Plan Receivables by Credit Category	The following table provides delinquency status for the EIP portfolio segment on a gross basis, which we actively monitor as part of our current credit risk management practices and policies: December 31, 2017 December 31, 2016 (in millions) Prime Subprime Total EIP Receivables, gross Prime Subprime Total EIP Receivables, gross Current - 30 days past due $ 1,727 $ 2,133 $ 3,860 $ 1,375 $ 1,735 $ 3,110 31 - 60 days past due 17 29 46 27 38 65 61 - 90 days past due 6 16 22 7 16 23 More than 90 days past due 8 24 32 10 22 32 Total receivables, gross $ 1,758 $ 2,202 $ 3,960 $ 1,419 $ 1,811 $ 3,230

Sales of Certain Receivables (T

Sales of Certain Receivables (Tables)	12 Months Ended
	Dec. 31, 2017
Transfers and Servicing [Abstract]
Schedule of Variable Interest Entities	The following table summarizes the carrying amounts and classification of assets, which consists primarily of the deferred purchase price and liabilities included in our Consolidated Balance Sheets that relate to our variable interest in the Service VIE: (in millions) December 31, December 31, Other current assets $ 236 $ 207 Accounts payable and accrued liabilities 25 17 Other current liabilities 180 129
Schedule of variable interest entities - EIP	The following table summarizes the carrying amounts and classification of assets, which consists primarily of the deferred purchase price and liabilities included in our Consolidated Balance Sheets that relate to the EIP BRE: (in millions) December 31, December 31, Other current assets $ 403 $ 371 Other assets 109 83 Other long-term liabilities 3 4
Schedule of Factoring Arrangement	The following table summarizes the impacts of the sale of certain service receivables and EIP receivables in our Consolidated Balance Sheets : (in millions) December 31, December 31, Derecognized net service receivables and EIP receivables $ 2,725 $ 2,502 Other current assets 639 578 of which, deferred purchase price 636 576 Other long-term assets 109 83 of which, deferred purchase price 109 83 Accounts payable and accrued liabilities 25 17 Other current liabilities 180 129 Other long-term liabilities 3 4 Net cash proceeds since inception 2,058 2,030 Of which: Change in net cash proceeds during the year-to-date period 28 536 Net cash proceeds funded by reinvested collections 2,030 1,494

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	The components of property and equipment were as follows: (in millions) Useful Lives December 31, December 31, Buildings and equipment Up to 40 years $ 2,066 $ 1,657 Wireless communications systems Up to 20 years 32,706 29,272 Leasehold improvements Up to 12 years 1,182 1,068 Capitalized software Up to 10 years 10,563 8,488 Leased wireless devices Up to 18 months 1,209 2,624 Construction in progress 1,771 2,613 Accumulated depreciation and amortization (27,301 ) (24,779 ) Property and equipment, net $ 22,196 $ 20,943
Schedule of Leased Wireless Devices	The components of leased wireless devices under our JUMP! On Demand program were as follows: (in millions) December 31, December 31, Leased wireless devices, gross $ 1,209 $ 2,624 Accumulated depreciation (417 ) (1,193 ) Leased wireless devices, net $ 792 $ 1,431
Schedule of Future Minimum Rental Payments	Future minimum payments expected to be received over the lease term related to the leased wireless devices, which exclude optional residual buy-out amounts at the end of the lease term, are summarized below: (in millions) Total Year Ended December 31, 2018 $ 485 2019 104 Total $ 589
Schedule of Asset Retirement Obligations	Activity in our asset retirement obligations was as follows: (in millions) December 31, December 31, Asset retirement obligations, beginning of year $ 539 $ 483 Liabilities incurred 25 50 Liabilities settled (16 ) (67 ) Accretion expense 27 24 Changes in estimated cash flows (13 ) 49 Asset retirement obligations, end of year $ 562 $ 539 Classified on the balance sheet as: Other current liabilities $ 3 $ 16 Other long-term liabilities 559 523 Asset retirement obligations $ 562 $ 539

Goodwill, Spectrum Licenses a31

Goodwill, Spectrum Licenses and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Spectrum Licenses	The following table summarizes our spectrum license activity for the years ended December 31, 2017 and 2016 : (in millions) December 31, 2017 December 31, 2016 Spectrum licenses, beginning of year $ 27,014 $ 23,955 Spectrum license acquisitions 8,599 3,334 Spectrum licenses transferred to held for sale (271 ) (324 ) Costs to clear spectrum 24 49 Spectrum licenses, end of year $ 35,366 $ 27,014
Schedule of Other Intangible Assets	The components of Other intangible assets were as follows: Useful Lives December 31, 2017 December 31, 2016 (in millions) Gross Amount Accumulated Amortization Net Amount Gross Amount Accumulated Amortization Net Amount Customer lists Up to 6 years $ 1,104 $ (1,016 ) $ 88 $ 1,104 $ (894 ) $ 210 Trademarks and patents Up to 19 years 307 (192 ) 115 303 (156 ) 147 Other Up to 28 years 49 (35 ) 14 50 (31 ) 19 Other intangible assets $ 1,460 $ (1,243 ) $ 217 $ 1,457 $ (1,081 ) $ 376
Schedule of Estimated Aggregate Future Amortization Expense	The estimated aggregate future amortization expense for intangible assets subject to amortization are summarized below: (in millions) Estimated Future Amortization Year Ending December 31, 2018 $ 105 2019 52 2020 35 2021 14 2022 4 Thereafter 7 Total $ 217

Fair Value Measurements and D32

Fair Value Measurements and Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Derivative Instruments	The fair value of embedded derivative instruments by balance sheet location and level were as follows: December 31, 2017 (in millions) Level 1 Level 2 Level 3 Total Other long-term liabilities $ — $ — $ 66 $ 66 December 31, 2016 (in millions) Level 1 Level 2 Level 3 Total Other long-term liabilities $ — $ — $ 118 $ 118
Schedule of Gains (Losses) on Derivative Instruments	The following table summarizes the gain (loss) activity related to embedded derivatives instruments recognized in Interest expense to affiliates: Year Ended December 31, (in millions) 2017 2016 2015 Embedded derivatives $ 52 $ 25 $ (148 )
Schedule of Carrying Values and Fair Values of Long-term Debt	The carrying amounts and fair values of our assets and liabilities measured at fair value on a recurring basis included in our Consolidated Balance Sheets were as follows: Level within the Fair Value Hierarchy December 31, 2017 December 31, 2016 (in millions) Carrying Amount Fair Value Carrying Amount Fair Value Assets: Deferred purchase price assets 3 $ 745 $ 745 $ 659 $ 659 Liabilities: Guarantee liabilities 3 105 105 135 135 The principal amounts and fair values of our short-term and long-term debt included in our Consolidated Balance Sheets were as follows: Level within the Fair Value Hierarchy December 31, 2017 December 31, 2016 (in millions) Principal Amount Fair Value Principal Amount Fair Value Liabilities: Senior Notes to third parties 1 $ 11,850 $ 12,540 $ 18,600 $ 19,584 Senior Notes to affiliates 2 7,500 7,852 — — Incremental Term Loan Facility to affiliates 2 4,000 4,020 — — Senior Reset Notes to affiliates 2 3,100 3,260 5,600 5,955 Senior Secured Term Loans 2 — — 1,980 2,005

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Debt	During the year ended December 31, 2017 , we issued the following Senior Notes to DT: (in millions) Principal Issuances (Redemptions) Discounts (1) Net Proceeds from Issuance of Long-Term Debt 4.000% Senior Notes due 2022 $ 1,000 $ (23 ) $ 977 5.125% Senior Notes due 2025 1,250 (28 ) 1,222 5.375% Senior Notes due 2027 (2) 1,250 (28 ) 1,222 6.288% Senior Reset Notes due 2019 (1,250 ) — (1,250 ) 6.366% Senior Reset Notes due 2020 (1,250 ) — (1,250 ) Total $ 1,000 $ (79 ) $ 921 (1) Discounts reduce Proceeds from issuance of long-term debt and are included within Net cash (used in) provided by financing activities in our Consolidated Statements of Cash Flows . (2) In April 2017, we issued to DT $750 million in aggregate principal amount of the 5.375% Senior Notes due 2027 , and in September 2017, we issued to DT the remaining $500 million in aggregate principal amount of the 5.375% Senior Notes due 2027 . Debt was as follows: (in millions) December 31, December 31, 5.250% Senior Notes due 2018 $ — $ 500 6.464% Senior Notes due 2019 — 1,250 6.288% Senior Reset Notes to affiliates due 2019 — 1,250 6.542% Senior Notes due 2020 — 1,250 6.625% Senior Notes due 2020 — 1,000 6.366% Senior Reset Notes to affiliates due 2020 — 1,250 6.250% Senior Notes due 2021 — 1,750 6.633% Senior Notes due 2021 — 1,250 5.300% Senior Notes to affiliates due 2021 2,000 — 8.097% Senior Reset Notes to affiliates due 2021 1,250 1,250 6.125% Senior Notes due 2022 1,000 1,000 6.731% Senior Notes due 2022 — 1,250 4.000% Senior Notes due 2022 500 — 4.000% Senior Notes to affiliates due 2022 1,000 — 8.195% Senior Reset Notes to affiliates due 2022 1,250 1,250 Incremental term loan facility to affiliates due 2022 2,000 — 6.000% Senior Notes due 2023 1,300 1,300 6.625% Senior Notes due 2023 1,750 1,750 6.836% Senior Notes due 2023 600 600 9.332% Senior Reset Notes to affiliates due 2023 600 600 6.000% Senior Notes due 2024 1,000 1,000 6.500% Senior Notes due 2024 1,000 1,000 6.000% Senior Notes to affiliates due 2024 1,350 — 6.000% Senior Notes to affiliates due 2024 650 — Incremental term loan facility to affiliates due 2024 2,000 — 5.125% Senior Notes due 2025 500 — 6.375% Senior Notes due 2025 1,700 1,700 5.125% Senior Notes to affiliates due 2025 1,250 — 6.500% Senior Notes due 2026 2,000 2,000 5.375% Senior Notes due 2027 500 — 5.375% Senior Notes to affiliates Due 2027 1,250 — Senior Secured Term Loans — 1,980 Capital leases 1,824 1,425 Unamortized premium from purchase price allocation fair value adjustment 78 212 Unamortized premium on debt to affiliates 59 — Unamortized discount on Senior Secured Term Loans — (8 ) Unamortized discount on affiliates Senior Notes (73 ) — Debt issuance cost (19 ) (23 ) Total debt 28,319 27,786 Less: Current portion of Senior Secured Term Loans — 20 Less: Current portion of Senior Notes 999 — Less: Current portion of capital leases 613 334 Total long-term debt $ 26,707 $ 27,432 Classified on the balance sheet as: Long-term debt $ 12,121 $ 21,832 Long-term debt to affiliates 14,586 5,600 Total long-term debt $ 26,707 $ 27,432 On May 9, 2017, we exercised our option under existing purchase agreements and issued the following Senior Notes to DT: (in millions) Principal Issuances Premium Net Proceeds from Issuance of Long-Term Debt 5.300% Senior Notes due 2021 $ 2,000 $ — $ 2,000 6.000% Senior Notes due 2024 1,350 40 1,390 6.000% Senior Notes due 2024 650 24 674 Total $ 4,000 $ 64 $ 4,064 During the year ended December 31, 2017 , we made the following borrowings: (in millions) Net Proceeds from Issuance of Long-Term Debt Extinguishments Write-off of Discounts and Issuance Costs (1) LIBOR plus 2.00% Senior Secured Term Loan due 2022 $ 2,000 $ — $ — LIBOR plus 2.00% Senior Secured Term Loan due 2024 2,000 — — LIBOR plus 2.750% Senior Secured Term Loan (2) — (1,980 ) 13 Total $ 4,000 $ (1,980 ) $ 13 (1) Write-off of discounts and issuance costs are included in Other expense, net in our Consolidated Statements of Comprehensive Income and Other, net within Net cash provided by operating activities in our Consolidated Statements of Cash Flows . (2) Our Senior Secured Term Loan extinguished during the year ended December 31, 2017 was Third Party debt. During the year ended December 31, 2017 , we issued the following Senior Notes: (in millions) Principal Issuances Issuance Costs Net Proceeds from Issuance of Long-Term Debt 4.000% Senior Notes due 2022 $ 500 $ 2 $ 498 5.125% Senior Notes due 2025 500 2 498 5.375% Senior Notes due 2027 500 1 499 Total of Senior Notes issued $ 1,500 $ 5 $ 1,495
Debt Instrument Redemption	During the year ended December 31, 2017 , we made the following note redemptions: (in millions) Principal Amount Write-off of Premiums, Discounts and Issuance Costs (1) Call Penalties (1) (2) Redemption Redemption Price 6.625% Senior Notes due 2020 $ 1,000 $ (45 ) $ 22 February 10, 2017 102.208 % 5.250% Senior Notes due 2018 500 1 7 March 4, 2017 101.313 % 6.250% Senior Notes due 2021 1,750 (71 ) 55 April 1, 2017 103.125 % 6.464% Senior Notes due 2019 1,250 — — April 28, 2017 100.000 % 6.542% Senior Notes due 2020 1,250 — 21 April 28, 2017 101.636 % 6.633% Senior Notes due 2021 1,250 — 41 April 28, 2017 103.317 % 6.731% Senior Notes due 2022 1,250 — 42 April 28, 2017 103.366 % Total note redemptions $ 8,250 $ (115 ) $ 188 (1) Write-off of premiums, discounts, issuance costs and call penalties are included in Other expense, net in our Consolidated Statements of Comprehensive Income . Write-off of premiums, discounts and issuance costs are included in Other, net within Net cash provided by operating activities in our Consolidated Statements of Cash Flows . (2) The call penalty is the excess paid over the principal amount. Call penalties are included within Net cash provided by operating activities in our Consolidated Statements of Cash Flows .
Schedule of Future Minimum Lease Payments for Capital Leases	Future minimum payments required under capital leases, including interest and maintenance, over their remaining terms are summarized below: (in millions) Future Minimum Payments Year Ended December 31, 2018 $ 682 2019 634 2020 338 2021 151 2022 67 Thereafter 172 Total $ 2,044 Included in Total Interest $ 169 Maintenance 51
Schedule of Letters of Credit	The following table summarizes the outstanding standby letters of credit under each agreement: (in millions) December 31, December 31, JP Morgan Chase $ 20 $ 20 Deutsche Bank 59 54 Total outstanding balance $ 79 $ 74

Tower Obligations (Tables)

Tower Obligations (Tables)	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Summary of Impacts to Consolidated Balance Sheets	The following table summarizes the impacts to the Consolidated Balance Sheets : (in millions) December 31, December 31, Property and equipment, net $ 402 $ 485 Long-term financial obligation 2,590 2,621

Employee Compensation and Ben35

Employee Compensation and Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Stock-based Compensation Expense and Related Income Tax Benefits	Stock-based compensation expense and related income tax benefits were as follows: (in millions, except shares, per share and contractual life amounts) December 31, December 31, December 31, Stock-based compensation expense $ 306 $ 235 $ 201 Income tax benefit related to stock-based compensation 73 80 71 Realized excess tax benefit — — 79 Weighted average fair value per stock award granted 60.21 45.07 35.56 Unrecognized compensation expense 445 389 327 Weighted average period to be recognized (years) 1.9 2.0 2.0 Fair value of stock awards vested 503 354 445
Schedule of RSU and PRSU Awards Activity	The following activity occurred under the RSU and PRSU awards: (in millions, except shares, per share and contractual life amounts) Number of Units (1) Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Nonvested, December 31, 2016 15,715,391 $ 37.93 1.1 $ 904 Granted 7,133,359 60.21 Vested (8,338,271 ) 35.47 Forfeited (814,936 ) 49.02 Nonvested, December 31, 2017 13,695,543 50.38 1.1 870 (1) PRSUs included in the table above are shown at target. Share payout can range from 0 to 200% based on different performance outcomes.
Schedule of Stock Options Activity	The following activity occurred under the Predecessor Plans: Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (Years) Outstanding and exercisable, December 31, 2016 833,931 $ 31.75 2.3 Exercised (450,873 ) 44.18 Expired (9,900 ) 45.76 Outstanding and exercisable, December 31, 2017 373,158 16.36 2.8
Schedule of Compensation Expense Related to LTIP	Compensation expense reported within operating expenses related to our LTIP and payments to participants related to our LTIP were as follows: (in millions) December 31, December 31, December 31, Compensation expense $ — $ — $ 27 Payments — 52 57

Repurchases of Common Stock (Ta

Repurchases of Common Stock (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Schedule of Repurchases of Common Stock	The following table summarizes information regarding repurchases of our common stock: (In millions, except shares and per share price) Number of Shares Repurchased Average Price Paid Per Share Total Purchase Price Year Ended December 31, 2017 7,010,889 $ 63.34 $ 444

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax	Our sources of Income before income taxes were as follows: Year Ended December 31, (in millions) 2017 2016 2015 U.S. $ 3,274 $ 2,286 $ 898 Puerto Rico (113 ) 41 80 Income before income taxes $ 3,161 $ 2,327 $ 978
Schedule of Components of Income Tax Expense (Benefit)	Income tax expense is summarized as follows: Year Ended December 31, (in millions) 2017 2016 2015 Current tax benefit (expense) Federal $ — $ 66 $ 30 State (28 ) (29 ) (2 ) Puerto Rico (1 ) 10 (17 ) Total current tax benefit (expense) (29 ) 47 11 Deferred tax benefit (expense) Federal 1,182 (804 ) (281 ) State 173 (96 ) 37 Puerto Rico 49 (14 ) (12 ) Total deferred tax benefit (expense) 1,404 (914 ) (256 ) Total income tax benefit (expense) $ 1,375 $ (867 ) $ (245 )
Schedule of Effective Income Tax Rate Reconciliation	The reconciliation between the U.S. federal statutory income tax rate and our effective income tax rate is as follows: Year Ended December 31, 2017 2016 2015 Federal statutory income tax rate 35.0 % 35.0 % 35.0 % Effect of the Tax Cuts and Jobs Act (68.9 ) — — Change in valuation allowance (11.4 ) 1.0 (3.2 ) State taxes, net of federal benefit 4.8 4.0 (1.1 ) Equity-based compensation (2.4 ) (2.2 ) — Puerto Rico taxes, net of federal benefit (1.5 ) — 3.3 Permanent differences 0.5 0.6 1.6 Federal tax credits, net of reserves 0.3 (0.5 ) (9.5 ) Other, net 0.1 (0.6 ) (1.0 ) Effective income tax rate (43.5 )% 37.3 % 25.1 %
Schedule of Deferred Tax Assets and Liabilities	Significant components of deferred income tax assets and liabilities, tax effected, are as follows: (in millions) December 31, December 31, Deferred tax assets Loss carryforwards $ 1,576 $ 1,442 Deferred rents 759 1,153 Reserves and accruals 667 1,058 Federal and state tax credits 298 284 Debt fair market value adjustment — 83 Other 403 430 Deferred tax assets, gross 3,703 4,450 Valuation allowance (273 ) (573 ) Deferred tax assets, net 3,430 3,877 Deferred tax liabilities Spectrum licenses 5,038 6,952 Property and equipment 1,840 1,732 Other intangible assets 41 119 Other 48 12 Total deferred tax liabilities 6,967 8,815 Net deferred tax liabilities $ 3,537 $ 4,938 Classified on the balance sheet as: Deferred tax liabilities $ 3,537 $ 4,938
Schedule of Unrecognized Tax Benefits Roll Forward	A reconciliation of the beginning and ending amount of unrecognized tax benefits were as follows: Year Ended December 31, (in millions) 2017 2016 2015 Unrecognized tax benefits, beginning of year $ 410 $ 411 $ 388 Gross decreases to tax positions in prior periods (10 ) (5 ) (112 ) Gross increases to current period tax positions 12 4 135 Unrecognized tax benefits, end of year $ 412 $ 410 $ 411

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Earnings Per Share	The computation of basic and diluted earnings per share was as follows: Year Ended December 31, (in millions, except shares and per share amounts) 2017 2016 2015 Net income $ 4,536 $ 1,460 $ 733 Less: Dividends on mandatory convertible preferred stock (55 ) (55 ) (55 ) Net income attributable to common stockholders - basic 4,481 1,405 678 Add: Dividends related to mandatory convertible preferred stock 55 — — Net income attributable to common stockholders - diluted $ 4,536 $ 1,405 $ 678 Weighted average shares outstanding - basic 831,850,073 822,470,275 812,994,028 Effect of dilutive securities: Outstanding stock options and unvested stock awards 9,200,873 10,584,270 9,623,910 Mandatory convertible preferred stock 30,736,504 — — Weighted average shares outstanding - diluted 871,787,450 833,054,545 822,617,938 Earnings per share - basic $ 5.39 $ 1.71 $ 0.83 Earnings per share - diluted $ 5.20 $ 1.69 $ 0.82 Potentially dilutive securities: Outstanding stock options and unvested stock awards 33,980 3,528,683 4,842,370 Mandatory convertible preferred stock — 32,238,000 32,238,000

Additional Financial Informat39

Additional Financial Information (Tables)	12 Months Ended
	Dec. 31, 2017
Supplemental Financial Statement Elements [Abstract]
Schedule of Accounts Payable and Accrued Liabilities	Accounts payable and accrued liabilities are summarized as follows: (in millions) December 31, December 31, Accounts payable $ 6,182 $ 5,163 Payroll and related benefits 614 559 Property and other taxes, including payroll 620 525 Interest 253 423 Commissions 324 159 Network decommissioning 92 101 Toll and interconnect 109 85 Advertising 46 44 Other 288 93 Accounts payable and accrued liabilities $ 8,528 $ 7,152
Schedule of Related Party Transactions	The following table summarizes the impact of significant transactions with Deutsche Telekom or its affiliates included in operating expenses in the Consolidated Statements of Comprehensive Income : Year Ended December 31, (in millions) 2017 2016 2015 Discount related to roaming expenses $ — $ (15 ) $ (21 ) Fees incurred for use of the T-Mobile brand 79 74 65 Expenses for telecommunications and IT services 12 25 23 International long distance agreement 55 60 —

Guarantor Financial Informati40

Guarantor Financial Information (Tables)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule of Condensed Consolidating Balance Sheet Information	Condensed Consolidating Balance Sheet Information December 31, 2017 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Assets Current assets Cash and cash equivalents $ 74 $ 1 $ 1,086 $ 58 $ — $ 1,219 Accounts receivable, net — — 1,659 256 — 1,915 Equipment installment plan receivables, net — — 2,290 — — 2,290 Accounts receivable from affiliates — — 22 — — 22 Inventories — — 1,566 — — 1,566 Other current assets — — 1,275 628 — 1,903 Total current assets 74 1 7,898 942 — 8,915 Property and equipment, net (1) — — 21,890 306 — 22,196 Goodwill — — 1,683 — — 1,683 Spectrum licenses — — 35,366 — — 35,366 Other intangible assets, net — — 217 — — 217 Investments in subsidiaries, net 22,534 40,988 — — (63,522 ) — Intercompany receivables and note receivables — 8,503 — — (8,503 ) — Equipment installment plan receivables due after one year, net — — 1,274 — — 1,274 Other assets — 2 814 236 (140 ) 912 Total assets $ 22,608 $ 49,494 $ 69,142 $ 1,484 $ (72,165 ) $ 70,563 Liabilities and Stockholders' Equity Current liabilities Accounts payable and accrued liabilities $ — $ 253 $ 8,014 $ 261 $ — $ 8,528 Payables to affiliates — 146 36 — — 182 Short-term debt — 999 613 — — 1,612 Deferred revenue — — 779 — — 779 Other current liabilities 17 — 192 205 — 414 Total current liabilities 17 1,398 9,634 466 — 11,515 Long-term debt — 10,911 1,210 — — 12,121 Long-term debt to affiliates — 14,586 — — — 14,586 Tower obligations (1) — — 392 2,198 — 2,590 Deferred tax liabilities — — 3,677 — (140 ) 3,537 Deferred rent expense — — 2,720 — — 2,720 Negative carrying value of subsidiaries, net — — 629 — (629 ) — Intercompany payables and debt 32 — 8,201 270 (8,503 ) — Other long-term liabilities — 65 866 4 — 935 Total long-term liabilities 32 25,562 17,695 2,472 (9,272 ) 36,489 Total stockholders' equity (deficit) 22,559 22,534 41,813 (1,454 ) (62,893 ) 22,559 Total liabilities and stockholders' equity $ 22,608 $ 49,494 $ 69,142 $ 1,484 $ (72,165 ) $ 70,563 (1) Assets and liabilities for Non-Guarantor Subsidiaries are primarily included in VIEs related to the 2012 Tower Transaction. See Note 8 – Tower Obligations for further information. Condensed Consolidating Balance Sheet Information December 31, 2016 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Assets Current assets Cash and cash equivalents $ 358 $ 2,733 $ 2,342 $ 67 $ — $ 5,500 Accounts receivable, net — — 1,675 221 — 1,896 Equipment installment plan receivables, net — — 1,930 — — 1,930 Accounts receivable from affiliates — — 40 — — 40 Inventories — — 1,111 — — 1,111 Asset purchase deposit — — 2,203 — — 2,203 Other current assets — — 972 565 — 1,537 Total current assets 358 2,733 10,273 853 — 14,217 Property and equipment, net (1) — — 20,568 375 — 20,943 Goodwill — — 1,683 — — 1,683 Spectrum licenses — — 27,014 — — 27,014 Other intangible assets, net — — 376 — — 376 Investments in subsidiaries, net 17,682 35,095 — — (52,777 ) — Intercompany receivables and note receivables 196 6,826 — — (7,022 ) — Equipment installment plan receivables due after one year, net — — 984 — — 984 Other assets — 7 600 262 (195 ) 674 Total assets $ 18,236 $ 44,661 $ 61,498 $ 1,490 $ (59,994 ) $ 65,891 Liabilities and Stockholders' Equity Current liabilities Accounts payable and accrued liabilities $ — $ 423 $ 6,474 $ 255 $ — $ 7,152 Payables to affiliates — 79 46 — — 125 Short-term debt — 20 334 — — 354 Deferred revenue — — 986 — — 986 Other current liabilities — — 258 147 — 405 Total current liabilities — 522 8,098 402 — 9,022 Long-term debt — 20,741 1,091 — — 21,832 Long-term debt to affiliates — 5,600 — — — 5,600 Tower obligations (1) — — 400 2,221 — 2,621 Deferred tax liabilities — — 5,133 — (195 ) 4,938 Deferred rent expense — — 2,616 — — 2,616 Negative carrying value of subsidiaries, net — — 568 — (568 ) — Intercompany payables and debt — — 6,785 237 (7,022 ) — Other long-term liabilities — 116 906 4 — 1,026 Total long-term liabilities — 26,457 17,499 2,462 (7,785 ) 38,633 Total stockholders' equity (deficit) 18,236 17,682 35,901 (1,374 ) (52,209 ) 18,236 Total liabilities and stockholders' equity $ 18,236 $ 44,661 $ 61,498 $ 1,490 $ (59,994 ) $ 65,891 (1) Assets and liabilities for Non-Guarantor Subsidiaries are primarily included in VIEs related to the 2012 Tower Transaction. See Note 8 – Tower Obligations for further information.
Schedule of Condensed Consolidating Statement of Comprehensive Income Information	Condensed Consolidating Statement of Comprehensive Income Information Year Ended December 31, 2017 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Revenues Service revenues $ — $ — $ 28,894 $ 2,113 $ (847 ) $ 30,160 Equipment revenues — — 9,620 — (245 ) 9,375 Other revenues — 3 879 212 (25 ) 1,069 Total revenues — 3 39,393 2,325 (1,117 ) 40,604 Operating expenses Cost of services, exclusive of depreciation and amortization shown separately below — — 6,076 24 — 6,100 Cost of equipment sales — — 10,849 1,003 (244 ) 11,608 Selling, general and administrative — — 12,276 856 (873 ) 12,259 Depreciation and amortization — — 5,914 70 — 5,984 Gains on disposal of spectrum licenses — — (235 ) — — (235 ) Total operating expense — — 34,880 1,953 (1,117 ) 35,716 Operating income — 3 4,513 372 — 4,888 Other income (expense) Interest expense — (811 ) (109 ) (191 ) — (1,111 ) Interest expense to affiliates — (560 ) (23 ) — 23 (560 ) Interest income 1 29 10 — (23 ) 17 Other (expense) income, net — (88 ) 16 (1 ) — (73 ) Total other income (expense), net 1 (1,430 ) (106 ) (192 ) — (1,727 ) Income (loss) before income taxes 1 (1,427 ) 4,407 180 — 3,161 Income tax benefit (expense) — — 1,527 (152 ) — 1,375 Earnings (loss) of subsidiaries 4,535 5,962 (57 ) — (10,440 ) — Net income 4,536 4,535 5,877 28 (10,440 ) 4,536 Dividends on preferred stock (55 ) — — — — (55 ) Net income attributable to common stockholders $ 4,481 $ 4,535 $ 5,877 $ 28 $ (10,440 ) $ 4,481 Net Income $ 4,536 $ 4,535 $ 5,877 $ 28 $ (10,440 ) $ 4,536 Other comprehensive income, net of tax Other comprehensive income, net of tax 7 7 7 — (14 ) 7 Total comprehensive income $ 4,543 $ 4,542 $ 5,884 $ 28 $ (10,454 ) $ 4,543 Condensed Consolidating Statement of Comprehensive Income Information Year Ended December 31, 2016 (in millions) Parent Issuer Guarantor Subsidiaries (As adjusted - See Note 1 ) Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated (As adjusted - See Note 1 ) Revenues Service revenues $ — $ — $ 26,613 $ 2,023 $ (792 ) $ 27,844 Equipment revenues — — 9,145 — (418 ) 8,727 Other revenues — 3 739 (1) 195 (18 ) 919 Total revenues — 3 36,497 (1) 2,218 (1,228 ) 37,490 Operating expenses Cost of services, exclusive of depreciation and amortization shown separately below — — 5,707 24 — 5,731 Cost of equipment sales — — 10,209 1,027 (417 ) 10,819 Selling, general and administrative — — 11,321 868 (811 ) 11,378 Depreciation and amortization — — 6,165 78 — 6,243 Cost of MetroPCS business combination — — 104 — — 104 Gains on disposal of spectrum licenses — — (835 ) — — (835 ) Total operating expenses — — 32,671 1,997 (1,228 ) 33,440 Operating income — 3 3,826 (1) 221 — 4,050 Other income (expense) Interest expense — (1,147 ) (82 ) (189 ) — (1,418 ) Interest expense to affiliates — (312 ) — — — (312 ) Interest income (expense) — 31 (18 ) (1) — — 13 Other income (expense), net — 2 (8 ) — — (6 ) Total other expense, net — (1,426 ) (108 ) (1) (189 ) — (1,723 ) Income (loss) before income taxes — (1,423 ) 3,718 32 — 2,327 Income tax expense — — (857 ) (10 ) — (867 ) Earnings (loss) of subsidiaries 1,460 2,883 (17 ) — (4,326 ) — Net income 1,460 1,460 2,844 22 (4,326 ) 1,460 Dividends on preferred stock (55 ) — — — — (55 ) Net income attributable to common stockholders $ 1,405 $ 1,460 $ 2,844 $ 22 $ (4,326 ) $ 1,405 Net income $ 1,460 $ 1,460 $ 2,844 $ 22 $ (4,326 ) $ 1,460 Other comprehensive income, net of tax Other comprehensive income, net of tax 2 2 2 2 (6 ) 2 Total comprehensive income $ 1,462 $ 1,462 $ 2,846 $ 24 $ (4,332 ) $ 1,462 (1) The amortized imputed discount on EIP receivables previously recognized as Interest income has been retrospectively reclassified as Other revenues. See Note 1 - Summary of Significant Accounting Policies for further information. Condensed Consolidating Statement of Comprehensive Income Information Year Ended December 31, 2015 (in millions) Parent Issuer Guarantor Subsidiaries (As adjusted - See Note 1 ) Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated (As adjusted - See Note 1 ) Revenues Service revenues $ — $ — $ 23,748 $ 1,669 $ (596 ) $ 24,821 Equipment revenues — — 7,148 — (430 ) 6,718 Other revenues — 1 770 (1) 171 (14 ) 928 Total revenues — 1 31,666 (1) 1,840 (1,040 ) 32,467 Operating expenses Cost of services, exclusive of depreciation and amortization shown separately below — — 5,530 24 — 5,554 Cost of equipment sales — — 9,055 720 (431 ) 9,344 Selling, general and administrative — — 10,065 733 (609 ) 10,189 Depreciation and amortization — — 4,605 83 — 4,688 Cost of MetroPCS business combination — — 376 — — 376 Gains on disposal of spectrum licenses — — (163 ) — — (163 ) Total operating expenses — — 29,468 1,560 (1,040 ) 29,988 Operating income — 1 2,198 (1) 280 — 2,479 Other income (expense) Interest expense — (847 ) (50 ) (188 ) — (1,085 ) Interest expense to affiliates — (411 ) — — — (411 ) Interest income — 2 4 (1) — — 6 Other expense, net — (10 ) — (1 ) — (11 ) Total other expense, net — (1,266 ) (46 ) (1) (189 ) — (1,501 ) Income (loss) before income taxes — (1,265 ) 2,152 91 — 978 Income tax expense — — (214 ) (31 ) — (245 ) Earnings (loss) of subsidiaries 733 1,998 (48 ) — (2,683 ) — Net income 733 733 1,890 60 (2,683 ) 733 Dividends on preferred stock (55 ) — — — — (55 ) Net income attributable to common stockholders $ 678 $ 733 $ 1,890 $ 60 $ (2,683 ) $ 678 Net income $ 733 $ 733 $ 1,890 $ 60 $ (2,683 ) $ 733 Other comprehensive loss, net of tax Other comprehensive loss, net of tax (2 ) (2 ) (2 ) — 4 (2 ) Total comprehensive income $ 731 $ 731 $ 1,888 $ 60 $ (2,679 ) $ 731 (1) The amortized imputed discount on EIP receivables previously recognized as Interest income has been retrospectively reclassified as Other revenues. See Note 1 - Summary of Significant Accounting Policies for further information.
Schedule of Condensed Consolidating Statement of Cash Flows Information	Condensed Consolidating Statement of Cash Flows Information Year Ended December 31, 2017 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Operating activities Net cash provided by (used in) operating activities $ 1 $ (1,613 ) $ 9,616 $ 58 $ (100 ) $ 7,962 Investing activities Purchases of property and equipment — — (5,237 ) — — (5,237 ) Purchases of spectrum licenses and other intangible assets, including deposits — — (5,828 ) — — (5,828 ) Equity investment in subsidiary (308 ) — — — 308 — Other, net — — 1 — — 1 Net cash used in investing activities (308 ) — (11,064 ) — 308 (11,064 ) Financing activities Proceeds from issuance of long-term debt — 10,480 — — — 10,480 Proceeds from borrowing on revolving credit facility, net — 2,910 — — — 2,910 Repayments of revolving credit facility — — (2,910 ) — — (2,910 ) Repayments of capital lease obligations — — (486 ) — — (486 ) Repayments of short-term debt for purchases of inventory, property and equipment, net — — (300 ) — — (300 ) Repayments of long-term debt — — (10,230 ) — — (10,230 ) Proceeds from exercise of stock options 21 — — — — 21 Repurchases of common shares (427 ) — — — — (427 ) Intercompany advances, net 484 (14,817 ) 14,300 33 — — Equity investment from parent — 308 — — (308 ) — Tax withholdings on share-based awards — — (166 ) — — (166 ) Intercompany dividend paid — — — (100 ) 100 — Dividends on preferred stock (55 ) — — — — (55 ) Other, net — — (16 ) — — (16 ) Net cash provided by (used in) financing activities 23 (1,119 ) 192 (67 ) (208 ) (1,179 ) Change in cash and cash equivalents (284 ) (2,732 ) (1,256 ) (9 ) — (4,281 ) Cash and cash equivalents Beginning of period 358 2,733 2,342 67 — 5,500 End of period $ 74 $ 1 $ 1,086 $ 58 $ — $ 1,219 Condensed Consolidating Statement of Cash Flows Information Year Ended December 31, 2016 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Operating activities Net cash provided by (used in) operating activities $ 6 $ (1,335 ) $ 7,541 $ 33 $ (110 ) $ 6,135 Investing activities Purchases of property and equipment — — (4,702 ) — — (4,702 ) Purchases of spectrum licenses and other intangible assets, including deposits — — (3,968 ) — — (3,968 ) Sales of short-term investments — 2,000 998 — — 2,998 Other, net — — (8 ) — — (8 ) Net cash provided by (used in) investing activities — 2,000 (7,680 ) — — (5,680 ) Financing activities Proceeds from issuance of long-term debt — 997 — — — 997 Repayments of capital lease obligations — — (205 ) — — (205 ) Repayments of short-term debt for purchases of inventory, property and equipment, net — — (150 ) — — (150 ) Repayments of long-term debt — — (20 ) — — (20 ) Intercompany advances, net — (696 ) 625 71 — — Proceeds from exercise of stock options 29 — — — — 29 Tax withholdings on share-based awards — — (121 ) — — (121 ) Intercompany dividend paid — — — (110 ) 110 — Dividends on preferred stock (55 ) — — — — (55 ) Other, net — — (12 ) — — (12 ) Net cash (used in) provided by financing activities (26 ) 301 117 (39 ) 110 463 Change in cash and cash equivalents (20 ) 966 (22 ) (6 ) — 918 Cash and cash equivalents Beginning of period 378 1,767 2,364 73 — 4,582 End of period $ 358 $ 2,733 $ 2,342 $ 67 $ — $ 5,500 Condensed Consolidating Statement of Cash Flows Information Year Ended December 31, 2015 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Operating activities Net cash provided by (used in) operating activities $ (1 ) $ (1,147 ) $ 6,652 $ 85 $ (175 ) $ 5,414 Investing activities Purchases of property and equipment — — (4,724 ) — — (4,724 ) Purchases of spectrum licenses and other intangible assets, including deposits — — (1,935 ) — — (1,935 ) Purchases of short-term investments — (1,999 ) (998 ) — — (2,997 ) Investment in subsidiaries (1,905 ) — — — 1,905 — Other, net — — 96 — — 96 Net cash used in investing activities (1,905 ) (1,999 ) (7,561 ) — 1,905 (9,560 ) Financing activities Proceeds from capital contribution — 1,905 — — (1,905 ) — Proceeds from issuance of long-term debt — 3,979 — — — 3,979 Proceeds from tower obligations — 140 — — — 140 Repayments of capital lease obligations — — (57 ) — — (57 ) Repayments of short-term debt for purchases of inventory, property and equipment, net — — (564 ) — — (564 ) Intercompany advances, net — (3,357 ) 3,288 69 — — Proceeds from exercise of stock options 47 — — — — 47 Intercompany dividend paid — — — (175 ) 175 — Tax withholdings on share-based awards — — (156 ) — — (156 ) Dividends on preferred stock (41 ) — (14 ) — — (55 ) Other, net — — 79 — — 79 Net cash provided by (used in) financing activities 6 2,667 2,576 (106 ) (1,730 ) 3,413 Change in cash and cash equivalents (1,900 ) (479 ) 1,667 (21 ) — (733 ) Cash and cash equivalents Beginning of period 2,278 2,246 697 94 — 5,315 End of period $ 378 $ 1,767 $ 2,364 $ 73 $ — $ 4,582

Quarterly Financial Informati41

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information [Abstract]
Quarterly Financial Information	(in millions, except shares and per share amounts) First Quarter Second Quarter Third Quarter Fourth Quarter Full Year 2017 Total revenues $ 9,613 $ 10,213 $ 10,019 $ 10,759 $ 40,604 Operating income 1,037 1,416 1,323 1,112 4,888 Net income 698 581 550 2,707 4,536 Dividends on preferred stock (14 ) (14 ) (13 ) (14 ) (55 ) Net income attributable to common stockholders 684 567 537 2,693 4,481 Earnings per share Basic $ 0.83 $ 0.68 $ 0.65 $ 3.22 $ 5.39 Diluted 0.80 0.67 0.63 3.11 5.20 Weighted average shares outstanding Basic 827,723,034 830,971,528 831,189,779 837,416,683 831,850,073 Diluted 869,395,250 870,456,447 871,420,065 871,501,578 871,787,450 Net income includes: Gains on disposal of spectrum licenses $ (37 ) $ (1 ) $ (29 ) $ (168 ) $ (235 ) 2016 Total revenues (1) $ 8,664 $ 9,287 $ 9,305 $ 10,234 $ 37,490 Operating income (1) 1,168 833 1,048 1,001 4,050 Net income 479 225 366 390 1,460 Dividends on preferred stock (14 ) (14 ) (13 ) (14 ) (55 ) Net income attributable to common stockholders 465 211 353 376 1,405 Earnings per share Basic $ 0.57 $ 0.26 $ 0.43 $ 0.46 $ 1.71 Diluted 0.56 0.25 0.42 0.45 1.69 Weighted average shares outstanding Basic 819,431,761 822,434,490 822,998,697 824,982,734 822,470,275 Diluted 859,382,827 829,752,956 832,257,819 867,262,400 833,054,545 Net income includes: Cost of MetroPCS business combination $ 36 $ 59 $ 15 $ (6 ) $ 104 Gains on disposal of spectrum licenses (636 ) — (199 ) — (835 ) (1) The amortized imputed discount on EIP receivables previously recognized as Interest income has been retrospectively re-classified as Other revenues. See Note 1 - Summary of Significant Accounting Policies of the Notes to the Consolidated Financial Statements included in Part II, Item 8 of this Form 10-K for further information.

Summary of Significant Accoun42

Summary of Significant Accounting Policies - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)options	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jan. 01, 2018USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Device upgrade period	18 months
Number of upgrade options (per month) | options	1
Federal Universal Service Fund and other fees	$ 258	$ 409	$ 334
Advertising expense	$ 1,800	1,700	1,600
Average amortization period, deferred contract costs	24 months
Net cash provided by (used in) operating activities	$ 7,962	6,135	5,414
Net cash (used in) provided by financing activities	(1,179)	463	3,413
Net cash used in investing activities	(11,064)	(5,680)	$ (9,560)
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Commission costs	425
Accounting Standards Update 2014-09 | Scenario, Forecast
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Incremental contract acquisition costs requiring capitalization and amortization				$ 150
Accounting Standards Update 2014-09 | Scenario, Forecast | Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of initially applying new revenue standard				220
Accounting Standards Update 2014-09 | Adjustments for New Accounting Principle, Early Adoption | Scenario, Forecast
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Incremental contract acquisition costs requiring capitalization and amortization				$ 140
Accounting Standards Update 2016-15 | Adjustments for New Accounting Principle, Early Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities	(4,300)	(3,500)
Net cash used in investing activities	4,300	$ 3,500
Accounting Standards Update 2016-15 | Adjustment for Debt Prepayments and Debt Extinguishment Costs
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities	(188)
Net cash (used in) provided by financing activities	$ (188)

Summary of Significant Accoun43

Summary of Significant Accounting Policies - Change in Accounting Principle (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other revenues									$ 1,069	$ 919	$ 928
Total revenues	$ 10,759	$ 10,019	$ 10,213	$ 9,613	$ 10,234	$ 9,305	$ 9,287	$ 8,664	40,604	37,490	32,467
Operating income	1,112	1,323	1,416	1,037	1,001	1,048	833	1,168	4,888	4,050	2,479
Interest income									17	13	6
Total other expense, net									(1,727)	(1,723)	(1,501)
Net income	$ 2,707	$ 550	$ 581	$ 698	$ 390	$ 366	$ 225	$ 479	4,536	1,460	733
Discount On Equipment Installment Plan Receivables
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other revenues									1,069	919	928
Total revenues									40,604	37,490	32,467
Operating income									4,888	4,050	2,479
Interest income									17	13	6
Total other expense, net									(1,727)	(1,723)	(1,501)
Net income									4,536	1,460	733
Discount On Equipment Installment Plan Receivables | Unadjusted
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other revenues									789	671	514
Total revenues									40,324	37,242	32,053
Operating income									4,608	3,802	2,065
Interest income									297	261	420
Total other expense, net									(1,447)	(1,475)	(1,087)
Net income									4,536	1,460	733
Discount On Equipment Installment Plan Receivables | Change in Accounting Principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other revenues									280	248	414
Total revenues									280	248	414
Operating income									280	248	414
Interest income									(280)	(248)	(414)
Total other expense, net									(280)	(248)	(414)
Net income									$ 0	$ 0	$ 0

Receivables and Allowance for44

Receivables and Allowance for Credit Losses - EIP Receivables (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)classessegments	Dec. 31, 2016USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Portfolio segments | segments	2
Customer classes | classes	2
EIP receivables, gross	$ 3,960	$ 3,230
Unamortized imputed discount	(264)	(195)
EIP receivables, net of unamortized imputed discount	3,696	3,035
Allowance for credit losses	(132)	(121)
Equipment installment plan receivables, net	3,564	2,914
Equipment installment plan receivables, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Equipment installment plan receivables, net	2,290	1,930
Equipment installment plan receivables due after one year, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Equipment installment plan receivables, net	$ 1,274	$ 984

Receivables and Allowance for45

Receivables and Allowance for Credit Losses - Unamortized Imputed Discount and Allowance for Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses and imputed discount, beginning of period	$ 418	$ 449	$ 531
Bad debt expense	388	477	547
Write-offs, net of recoveries	(393)	(518)	(482)
Change in imputed discount on short-term and long-term EIP receivables	252	186	(84)
Impact on the imputed discount from sales of EIP receivables	(183)	(176)	(63)
Allowance for credit losses and imputed discount, end of period	482	418	449
Accounts Receivable Allowance
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses and imputed discount, beginning of period	102	116	83
Bad debt expense	104	227	182
Write-offs, net of recoveries	(120)	(241)	(149)
Allowance for credit losses and imputed discount, end of period	$ 86	$ 102	116
EIP Receivables Allowance
Financing Receivable, Allowance for Credit Losses [Line Items]
Weighted average effective imputed interest rate	9.60%	9.00%
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses and imputed discount, beginning of period	$ 316	$ 333	448
Bad debt expense	284	250	365
Write-offs, net of recoveries	(273)	(277)	(333)
Change in imputed discount on short-term and long-term EIP receivables	252	186	(84)
Impact on the imputed discount from sales of EIP receivables	(183)	(176)	(63)
Allowance for credit losses and imputed discount, end of period	$ 396	$ 316	$ 333

Receivables and Allowance for46

Receivables and Allowance for Credit Losses - Gross EIP Receivables by Credit Category (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	$ 3,960	$ 3,230
Prime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	1,758	1,419
Subprime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	2,202	1,811
Current - 30 days past due
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	3,860	3,110
Current - 30 days past due | Prime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	1,727	1,375
Current - 30 days past due | Subprime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	2,133	1,735
31 - 60 days past due
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	46	65
31 - 60 days past due | Prime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	17	27
31 - 60 days past due | Subprime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	29	38
61 - 90 days past due
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	22	23
61 - 90 days past due | Prime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	6	7
61 - 90 days past due | Subprime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	16	16
More than 90 days past due
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	32	32
More than 90 days past due | Prime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	8	10
More than 90 days past due | Subprime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	$ 24	$ 22

Sales of Certain Receivables -

Sales of Certain Receivables - Sales of Service Receivables (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Nov. 30, 2016
Variable Interest Entity [Line Items]
Other current assets	$ 1,903	$ 1,537
Accounts payable and accrued liabilities	8,528	7,152
Other current liabilities	414	405
Factoring Arrangement | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Revolving receivables facility, maximum borrowing capacity			$ 950
Revolving receivables facility, outstanding borrowings	880	907
Other current assets	236	207
Accounts payable and accrued liabilities	25	17
Other current liabilities	$ 180	$ 129

Sales of Certain Receivables 48

Sales of Certain Receivables - Sales of EIP Receivables (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Aug. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Other current assets	$ 1,903		$ 1,537
Other assets	912		674
EIP Securitization Arrangement
Variable Interest Entity [Line Items]
Revolving receivables facility, maximum borrowing capacity	1,300	$ 1,200
Revolving receivables facility, outstanding borrowings	$ 1,300		1,200
Equipment installment plan, maximum payment term	24 months
Other current assets	$ 403		371
Other assets	109		83
Other long-term liabilities	$ 3		$ 4

Sales of Certain Receivables 49

Sales of Certain Receivables - Sales of Receivables and Continuing Involvement (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]
Other current assets	$ 1,903	$ 1,537
Other long-term assets	912	674
Accounts payable and accrued liabilities	8,528	7,152
Other current liabilities	414	405
Other long-term liabilities	935	1,026
Losses from sales of receivables	299	228	$ 204
Factoring and EIP Securitization Arrangement | Transferor's Continuing Involvement in Transferred Financial Assets, Transfer Description
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]
Maximum exposure to loss, Factoring VIE	1,300
Factoring and EIP Securitization Arrangement
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]
Derecognized net service receivables and EIP receivables	2,725	2,502
Other current assets	639	578
Deferred purchase price assets	745	659
Other long-term assets	109	83
Accounts payable and accrued liabilities	25	17
Other current liabilities	180	129
Other long-term liabilities	3	4
Net cash proceeds since inception	2,058	2,030
Change in net cash proceeds during the year-to-date period	28	536
Net cash proceeds funded by reinvested collections	2,030	1,494
Losses from sales of receivables	299	228	$ 204
Factoring and EIP Securitization Arrangement | Other current assets - of which, deferred purchase price
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]
Deferred purchase price assets	636	576
Factoring and EIP Securitization Arrangement | Other long-term assets - of which, deferred purchase price
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]
Deferred purchase price assets	$ 109	$ 83

Property and Equipment - Proper

Property and Equipment - Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ (27,301)	$ (24,779)
Property and equipment, net	22,196	20,943
Capital leased assets, gross	2,400	1,600
Capital leased assets, accumulated amortization	533	300
Capitalized interest	136	142	$ 230
Depreciation expense	5,800	6,000	4,400
Additional depreciation expense	63	101	$ 85
Buildings and equipment
Property, Plant and Equipment [Line Items]
Property and equipment	2,066	1,657
Wireless communications systems
Property, Plant and Equipment [Line Items]
Property and equipment	32,706	29,272
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	1,182	1,068
Capitalized software
Property, Plant and Equipment [Line Items]
Property and equipment	10,563	8,488
Leased wireless devices
Property, Plant and Equipment [Line Items]
Property and equipment	1,209	2,624
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment	$ 1,771	$ 2,613
Maximum | Buildings and equipment
Property, Plant and Equipment [Line Items]
Useful life (in years)	40 years
Maximum | Wireless communications systems
Property, Plant and Equipment [Line Items]
Useful life (in years)	20 years
Maximum | Leasehold improvements
Property, Plant and Equipment [Line Items]
Useful life (in years)	12 years
Maximum | Capitalized software
Property, Plant and Equipment [Line Items]
Useful life (in years)	10 years
Maximum | Leased wireless devices
Property, Plant and Equipment [Line Items]
Useful life (in years)	18 months

Property and Equipment - Leased

Property and Equipment - Leased Wireless Devices (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property Subject to or Available for Operating Lease, Net [Abstract]
Leased wireless devices, gross	$ 1,209	$ 2,624
Accumulated depreciation	(417)	(1,193)
Leased wireless devices, net	792	1,431
Operating Leases, Future Minimum Payments Receivable [Abstract]
2,018	485
2,019	104
Total	589
Depreciation expense for leased devices	$ 1,000	$ 1,500	$ 312

Property and Equipment - Asset

Property and Equipment - Asset Retirement Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations, beginning of year	$ 539	$ 483
Liabilities incurred	25	50
Liabilities settled	(16)	(67)
Accretion expense	27	24
Changes in estimated cash flows	(13)	49
Asset retirement obligations, end of year	562	539
Asset retirement costs capitalized, net	220	258
Other current liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations, beginning of year	16
Asset retirement obligations, end of year	3	16
Other long-term liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations, beginning of year	523
Asset retirement obligations, end of year	$ 559	$ 523

Goodwill, Spectrum Licenses a53

Goodwill, Spectrum Licenses and Other Intangible Assets - Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, net change	$ 0	$ 0

Goodwill, Spectrum Licenses a54

Goodwill, Spectrum Licenses and Other Intangible Assets - Spectrum Licenses (Details) customer in Millions, $ in Millions	1 Months Ended					3 Months Ended								12 Months Ended
	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	May 31, 2017USD ($)	Apr. 30, 2017USD ($)Licenses	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)customer	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Indefinite-lived Intangible Assets [Roll Forward]
Gains on disposal of spectrum licenses						$ 168	$ 29	$ 1	$ 37	$ 0	$ 199	$ 0	$ 636	$ 235	$ 835	$ 163
Number of licenses | Licenses				1,525
Payments to acquire intangible assets														5,828	3,968	1,935
Asset purchase deposit	$ 0					0				2,203				0	2,203
Iowa Wireless
Indefinite-lived Intangible Assets [Roll Forward]
Unconsolidated subsidiary ownership percentage		54.00%					54.00%
Purchase price of unconsolidated subsidiary		$ 25
Licensing Agreements
Indefinite-lived Intangible Assets [Roll Forward]
Spectrum licenses, beginning of year									$ 27,014				23,955	27,014	23,955
Spectrum license acquisitions													1,200	8,599	3,334
Spectrum licenses transferred to held for sale														(271)	(324)
Costs to clear spectrum														24	49
Spectrum licenses, end of year	35,366					$ 35,366				27,014				$ 35,366	27,014	$ 23,955
Gains on disposal of spectrum licenses	168	29			$ 37								$ 636		199
Payments to acquire intangible assets				$ 8,000						$ 420					1,300
Asset purchase deposit												$ 2,200
Remaining purchase price			$ 5,800
Number of customers covered by purchase of intangible assets | customer										11
Licensing Agreements | Fair Value
Indefinite-lived Intangible Assets [Roll Forward]
Spectrum license acquisitions	$ 352	$ 115			$ 123										$ 1,700

Goodwill, Spectrum Licenses a55

Goodwill, Spectrum Licenses and Other Intangible Assets - Other Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 0	$ 0
Indefinite-lived intangible asset impairment	0	0
Gross Amount	1,460,000,000	1,457,000,000
Accumulated Amortization	(1,243,000,000)	(1,081,000,000)
Net Amount	217,000,000	376,000,000
Amortization expense for intangible assets	163,000,000	220,000,000	$ 276,000,000
Future Amortization Expense
2,018	105,000,000
2,019	52,000,000
2,020	35,000,000
2,021	14,000,000
2,022	4,000,000
Thereafter	7,000,000
Net Amount	217,000,000	376,000,000
Customer lists
Finite-Lived Intangible Assets [Line Items]
Gross Amount	1,104,000,000	1,104,000,000
Accumulated Amortization	(1,016,000,000)	(894,000,000)
Net Amount	88,000,000	210,000,000
Future Amortization Expense
Net Amount	$ 88,000,000	210,000,000
Customer lists | Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life (in years)	6 years
Trademarks and patents
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 307,000,000	303,000,000
Accumulated Amortization	(192,000,000)	(156,000,000)
Net Amount	115,000,000	147,000,000
Future Amortization Expense
Net Amount	$ 115,000,000	147,000,000
Trademarks and patents | Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life (in years)	19 years
Other
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 49,000,000	50,000,000
Accumulated Amortization	(35,000,000)	(31,000,000)
Net Amount	14,000,000	19,000,000
Future Amortization Expense
Net Amount	$ 14,000,000	$ 19,000,000
Other | Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life (in years)	28 years

Fair Value Measurements and D56

Fair Value Measurements and Derivative Instruments - Fair Value of Financial Instruments by Level (Details) - Embedded Derivative Financial Instruments $ in Millions	Dec. 31, 2017USD ($)derivative_instruments	Dec. 31, 2016USD ($)derivative_instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of embedded derivative instruments | derivative_instruments	0	0
Other long-term liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded derivative instruments, liabilities	$ 66	$ 118
Other long-term liabilities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded derivative instruments, liabilities	0	0
Other long-term liabilities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded derivative instruments, liabilities	0	0
Other long-term liabilities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded derivative instruments, liabilities	$ 66	$ 118

Fair Value Measurements and D57

Fair Value Measurements and Derivative Instruments - Gains (Losses) on Derivative Instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Embedded derivatives	$ 52	$ 25	$ (148)
Embedded Derivative Financial Instruments | Interest Expense to Affiliates
Derivative [Line Items]
Embedded derivatives	$ 52	$ 25	$ (148)

Fair Value Measurements and D58

Fair Value Measurements and Derivative Instruments - Fair Value of Short-term Investments and Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Level 1 | Reported Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 11,850	$ 18,600
Level 1 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	12,540	19,584
Level 2 | Reported Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Term loans	0	1,980
Level 2 | Reported Value Measurement | Secured Term Loan [$4.0B]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Term loans	4,000	0
Level 2 | Reported Value Measurement | Affiliated Entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	3,100	5,600
Level 2 | Reported Value Measurement | Affiliated Entity | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	7,500	0
Level 2 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Term loans	0	2,005
Level 2 | Fair Value | Secured Term Loan [$4.0B]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Term loans	4,020	0
Level 2 | Fair Value | Affiliated Entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	3,260	5,955
Level 2 | Fair Value | Affiliated Entity | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	7,852	0
Level 3 | Reported Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred purchase price assets	745	659
Guarantee liabilities	105	135
Level 3 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred purchase price assets	745	659
Guarantee liabilities	$ 105	$ 135

Fair Value Measurements and D59

Fair Value Measurements and Derivative Instruments - Guarantee Liabilities (Details) $ in Billions	Dec. 31, 2017USD ($)
Fair Value Disclosures [Abstract]
Maximum potential for losses under guarantor liabilities	$ 2.5

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2017	Apr. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Capital leases	$ 1,824		$ 1,425
Premium	78		212
Discount	0		(8)
Debt issuance cost	(19)		(23)
Total debt	28,319		27,786
Less: Current portion of Senior Secured Term Loans	0		20
Less: Current portion of capital leases	613		334
Long-term Debt and Long-term Debt to Affiliates	26,707		27,432
Long-term debt	12,121		21,832
Long-term debt to affiliates	14,586		5,600
Secured Debt
Debt Instrument [Line Items]
Senior Secured Term Loans	0		1,980
Senior Notes
Debt Instrument [Line Items]
Less: Current portion of Senior Notes	999		0
Affiliated Entity
Debt Instrument [Line Items]
Premium	59		0
Discount	(73)		0
Long-term debt to affiliates	$ 14,586		5,600
5.250% Senior Notes due 2018
Debt Instrument [Line Items]
Interest rate, stated percentage	5.25%
Senior notes	$ 0		500
5.250% Senior Notes due 2018 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	5.25%
6.464% Senior Notes due 2019
Debt Instrument [Line Items]
Interest rate, stated percentage	6.464%
Senior notes	$ 0		1,250
6.464% Senior Notes due 2019 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	6.464%
6.288% Senior Reset Notes to affiliates due 2019 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	6.288%
Senior notes to affiliates	$ 0		1,250
6.288% Senior Reset Notes to affiliates due 2019 | Affiliated Entity | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage		6.288%
6.542% Senior Notes due 2020
Debt Instrument [Line Items]
Interest rate, stated percentage	6.542%
Senior notes	$ 0		1,250
6.542% Senior Notes due 2020 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	6.542%
6.625% Senior Notes due 2020
Debt Instrument [Line Items]
Interest rate, stated percentage	6.625%
Senior notes	$ 0		1,000
6.625% Senior Notes due 2020 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	6.625%
6.366% Senior Reset Notes to affiliates due 2020 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	6.366%
Senior notes to affiliates	$ 0		1,250
6.366% Senior Reset Notes to affiliates due 2020 | Affiliated Entity | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage		6.366%
6.250% Senior Notes due 2021
Debt Instrument [Line Items]
Interest rate, stated percentage	6.25%
Senior notes	$ 0		1,750
6.250% Senior Notes due 2021 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	6.25%
6.633% Senior Notes due 2021
Debt Instrument [Line Items]
Interest rate, stated percentage	6.633%
Senior notes	$ 0		1,250
6.633% Senior Notes due 2021 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	6.633%
5.300% Senior Notes to affiliates due 2021 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	5.30%
5.300% Senior Notes to affiliates due 2021 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	5.30%
Senior notes to affiliates	$ 2,000		0
8.097% Senior Reset Notes to affiliates due 2021 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	8.097%
Senior notes to affiliates	$ 1,250		1,250
6.125% Senior Notes due 2022
Debt Instrument [Line Items]
Interest rate, stated percentage	6.125%
Senior notes	$ 1,000		1,000
6.731% Senior Notes due 2022
Debt Instrument [Line Items]
Interest rate, stated percentage	6.731%
Senior notes	$ 0		1,250
6.731% Senior Notes due 2022 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	6.731%
4.000% Senior Notes due 2022
Debt Instrument [Line Items]
Interest rate, stated percentage	4.00%
Senior notes	$ 500		0
4.000% Senior Notes due 2022 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	4.00%
Senior notes to affiliates	$ 1,000		0
8.195% Senior Reset Notes to affiliates due 2022 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	8.195%
Senior notes to affiliates	$ 1,250		1,250
Incremental term loan facility to affiliates due 2022 | Affiliated Entity
Debt Instrument [Line Items]
Senior notes to affiliates	$ 2,000		0
6.000% Senior Notes due 2023
Debt Instrument [Line Items]
Interest rate, stated percentage	6.00%
Senior notes	$ 1,300		1,300
6.625% Senior Notes due 2023
Debt Instrument [Line Items]
Interest rate, stated percentage	6.625%
Senior notes	$ 1,750		1,750
6.836% Senior Notes due 2023
Debt Instrument [Line Items]
Interest rate, stated percentage	6.836%
Senior notes	$ 600		600
9.332% Senior Reset Notes to affiliates due 2023 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	9.332%
Senior notes to affiliates	$ 600		600
6.000% Senior Notes due 2024
Debt Instrument [Line Items]
Interest rate, stated percentage	6.00%
Senior notes	$ 1,000		1,000
6.500% Senior Notes due 2024
Debt Instrument [Line Items]
Interest rate, stated percentage	6.50%
Senior notes	$ 1,000		1,000
6.000% Senior Notes to affiliates due 2024 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	6.00%
6.000% Senior Notes to affiliates due 2024 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	6.00%
Senior notes to affiliates	$ 1,350		0
6.000% Senior Notes to affiliates due 2024 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	6.00%
6.000% Senior Notes to affiliates due 2024 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	6.00%
Senior notes to affiliates	$ 650		0
Incremental term loan facility to affiliates due 2024 | Affiliated Entity
Debt Instrument [Line Items]
Senior notes to affiliates	$ 2,000		0
5.125% Senior Notes due 2025
Debt Instrument [Line Items]
Interest rate, stated percentage	5.125%
Senior notes	$ 500		0
5.125% Senior Notes due 2025 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	5.125%
Senior notes to affiliates	$ 1,250		0
6.375% Senior Notes due 2025
Debt Instrument [Line Items]
Interest rate, stated percentage	6.375%
Senior notes	$ 1,700		1,700
6.500% Senior Notes due 2026
Debt Instrument [Line Items]
Interest rate, stated percentage	6.00%
Senior notes	$ 2,000		2,000
5.375% Senior Notes due 2027
Debt Instrument [Line Items]
Interest rate, stated percentage	5.375%
Senior notes	$ 500		0
5.375% Senior Notes due 2027 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	5.375%
Senior notes to affiliates	$ 1,250		$ 0

Debt - Debt to Third Parties -

Debt - Debt to Third Parties - Issuances and Borrowings (Details) - USD ($)	Jan. 25, 2018	Mar. 16, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 31, 2018	Sep. 30, 2017	Apr. 30, 2017	Mar. 31, 2017
Debt Instrument [Line Items]
Principal Issuances		$ 1,500,000,000	$ 1,500,000,000
Issuance Costs			5,000,000
Net Proceeds from Issuance of Long-Term Debt		$ 1,495,000,000	1,495,000,000
Proceeds from issuance of long-term debt			10,480,000,000	$ 997,000,000	$ 3,979,000,000
Subsequent Event
Debt Instrument [Line Items]
Issuance Costs	$ 7,000,000
4.000% Senior Notes Due 2022
Debt Instrument [Line Items]
Principal Issuances			500,000,000
Issuance Costs			2,000,000
Net Proceeds from Issuance of Long-Term Debt			$ 498,000,000
Interest rate, stated percentage			4.00%
4.000% Senior Notes Due 2022 | Issuer
Debt Instrument [Line Items]
Principal Issuances								$ 1,000,000,000	$ 500,000,000
Interest rate, stated percentage								4.00%	4.00%
5.125% Senior Notes due 2025
Debt Instrument [Line Items]
Principal Issuances			$ 500,000,000
Issuance Costs			2,000,000
Net Proceeds from Issuance of Long-Term Debt			$ 498,000,000
Interest rate, stated percentage			5.125%
5.125% Senior Notes due 2025 | Issuer
Debt Instrument [Line Items]
Principal Issuances								$ 1,250,000,000	$ 500,000,000
Interest rate, stated percentage								5.125%	5.125%
5.375% Senior Notes due 2027
Debt Instrument [Line Items]
Principal Issuances			$ 500,000,000
Issuance Costs			1,000,000
Net Proceeds from Issuance of Long-Term Debt			$ 499,000,000
Interest rate, stated percentage			5.375%
5.375% Senior Notes due 2027 | Issuer
Debt Instrument [Line Items]
Principal Issuances							$ 500,000,000	$ 750,000,000	$ 500,000,000
Interest rate, stated percentage							5.375%	5.375%	5.375%
4.500% Senior Notes due 2026 | Issuer | Subsequent Event
Debt Instrument [Line Items]
Principal Issuances	$ 1,000,000,000					$ 1,000,000,000
Interest rate, stated percentage	4.50%					4.50%
4.750% Senior Notes due 2028 | Issuer | Subsequent Event
Debt Instrument [Line Items]
Principal Issuances	$ 1,500,000,000					$ 1,500,000,000
Interest rate, stated percentage	4.75%					4.75%
4.500% Senior Notes due 2026 and 4.750% Senior Notes due 2028 | Issuer | Subsequent Event
Debt Instrument [Line Items]
Proceeds from issuance of long-term debt	$ 2,493,000,000
6.625% Senior Notes due 2023
Debt Instrument [Line Items]
Interest rate, stated percentage			6.625%
6.625% Senior Notes due 2023 | Issuer | Subsequent Event
Debt Instrument [Line Items]
Principal Issuances	1,750,000,000
6.836% Senior Notes due 2023
Debt Instrument [Line Items]
Interest rate, stated percentage			6.836%
6.836% Senior Notes due 2023 | Issuer | Subsequent Event
Debt Instrument [Line Items]
Principal Issuances	$ 600,000,000

Debt - Debt to Third Parties 62

Debt - Debt to Third Parties - Notes Redemption (Details) - USD ($)	Jan. 15, 2018	Apr. 28, 2017	Apr. 01, 2017	Mar. 04, 2017	Feb. 10, 2017	Dec. 31, 2017	Jan. 31, 2018
6.625% Senior Notes due 2020
Debt Instrument [Line Items]
Redemption price (as a percent)					102.208%
Interest rate, stated percentage						6.625%
5.250% Senior Notes due 2018
Debt Instrument [Line Items]
Redemption price (as a percent)				101.313%
Interest rate, stated percentage						5.25%
6.250% Senior Notes due 2021
Debt Instrument [Line Items]
Redemption price (as a percent)			103.125%
Interest rate, stated percentage						6.25%
6.464% Senior Notes due 2019
Debt Instrument [Line Items]
Redemption price (as a percent)		100.00%
Interest rate, stated percentage						6.464%
6.542% Senior Notes due 2020
Debt Instrument [Line Items]
Redemption price (as a percent)		101.636%
Interest rate, stated percentage						6.542%
6.633% Senior Notes due 2021
Debt Instrument [Line Items]
Redemption price (as a percent)		103.317%
Interest rate, stated percentage						6.633%
6.731% Senior Notes due 2022
Debt Instrument [Line Items]
Redemption price (as a percent)		103.366%
Interest rate, stated percentage						6.731%
6.125% Senior Notes due 2022
Debt Instrument [Line Items]
Interest rate, stated percentage						6.125%
Senior Notes
Debt Instrument [Line Items]
Principal Amount						$ 8,250,000,000
Write-off of Premiums, Discounts and Issuance Costs						115,000,000
Call Penalties						188,000,000
Senior Notes | 6.625% Senior Notes due 2020
Debt Instrument [Line Items]
Principal Amount						1,000,000,000
Write-off of Premiums, Discounts and Issuance Costs						45,000,000
Call Penalties						$ 22,000,000
Interest rate, stated percentage						6.625%
Senior Notes | 5.250% Senior Notes due 2018
Debt Instrument [Line Items]
Principal Amount						$ 500,000,000
Write-off of Premiums, Discounts and Issuance Costs						(1,000,000)
Call Penalties						$ 7,000,000
Interest rate, stated percentage						5.25%
Senior Notes | 6.250% Senior Notes due 2021
Debt Instrument [Line Items]
Principal Amount						$ 1,750,000,000
Write-off of Premiums, Discounts and Issuance Costs						71,000,000
Call Penalties						$ 55,000,000
Interest rate, stated percentage						6.25%
Senior Notes | 6.464% Senior Notes due 2019
Debt Instrument [Line Items]
Principal Amount						$ 1,250,000,000
Write-off of Premiums, Discounts and Issuance Costs						0
Call Penalties						$ 0
Interest rate, stated percentage						6.464%
Senior Notes | 6.542% Senior Notes due 2020
Debt Instrument [Line Items]
Principal Amount						$ 1,250,000,000
Write-off of Premiums, Discounts and Issuance Costs						0
Call Penalties						$ 21,000,000
Interest rate, stated percentage						6.542%
Senior Notes | 6.633% Senior Notes due 2021
Debt Instrument [Line Items]
Principal Amount						$ 1,250,000,000
Write-off of Premiums, Discounts and Issuance Costs						0
Call Penalties						$ 41,000,000
Interest rate, stated percentage						6.633%
Senior Notes | 6.731% Senior Notes due 2022
Debt Instrument [Line Items]
Principal Amount						$ 1,250,000,000
Write-off of Premiums, Discounts and Issuance Costs						0
Call Penalties						$ 42,000,000
Interest rate, stated percentage						6.731%
Senior Notes | 6.125% Senior Notes due 2022 | Subsequent Event
Debt Instrument [Line Items]
Principal Amount							$ 1,000,000,000
Redemption price (as a percent)	103.063%
Interest rate, stated percentage							6.125%
Redemption premium	$ 31,000,000
Write-off of issuance costs	$ 1,000,000

Debt - Debt to Affiliates - Iss

Debt - Debt to Affiliates - Issuances and Borrowings (Details) - USD ($)

Mar. 16, 2017

Dec. 31, 2017

Apr. 30, 2018

Jan. 31, 2018

Jan. 25, 2018

Jan. 22, 2018

Sep. 30, 2017

Jul. 31, 2017

May 31, 2017

Apr. 30, 2017

Mar. 31, 2017

Mar. 13, 2017

Jan. 31, 2017

Jan. 25, 2017

Dec. 31, 2016

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

$ 1,495,000,000

$ 1,495,000,000

Principal Issuances

$ 1,500,000,000

1,500,000,000

Issuance costs related to public debt issuance

5,000,000

Discount

0

$ (8,000,000)

Premium

78,000,000

212,000,000

Subsequent Event

Debt Instrument [Line Items]

Issuance costs related to public debt issuance

$ 7,000,000

Affiliated Entity

Debt Instrument [Line Items]

Discount

(73,000,000)

0

Premium

59,000,000

0

Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

921,000,000

Net Proceeds from Issuance of Long-Term Debt

921,000,000

Principal Issuances

1,000,000,000

Discount

$ (79,000,000)

LIBOR plus 2.00% Senior Secured Term Loan due 2022 | Affiliated Entity | London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Interest rate, stated percentage

2.00%

LIBOR plus 2.00% Senior Secured Term Loan due 2022 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Senior Secured Term Loans

$ 2,000,000,000

Applicable margin, percentage

2.00%

LIBOR plus 2.00% Senior Secured Term Loan due 2024 | Affiliated Entity | London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Interest rate, stated percentage

2.00%

LIBOR plus 2.00% Senior Secured Term Loan due 2024 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Senior Secured Term Loans

$ 2,000,000,000

Applicable margin, percentage

2.00%

LIBOR plus 2.750% Senior Secured Term Loan | Affiliated Entity | London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Interest rate, stated percentage

2.75%

Incremental Term Loan Facility

Debt Instrument [Line Items]

Principal Issuances

$ 4,000,000,000

Incremental Term Loan Facility | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Principal Issuances

$ 4,000,000,000

Refinanced Secured Term Loans

Debt Instrument [Line Items]

Senior Secured Term Loans

1,980,000,000

Refinanced Secured Term Loans | Affiliated Entity

Debt Instrument [Line Items]

Senior Secured Term Loans

1,980,000,000

2.25% Margin Plus LIBOR Secured Term Loan due 2024 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Senior Secured Term Loans

$ 2,000,000,000

Applicable margin, percentage

2.25%

2.00% Margin Plus LIBOR Secured Term Loan due 2022 and 2.25% Margin Plus LIBOR Secured Term Loan due 2024 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Issuance costs related to public debt issuance

$ 0

4.000% Senior Notes Due 2022

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

498,000,000

Principal Issuances

500,000,000

Issuance costs related to public debt issuance

$ 2,000,000

Interest rate, stated percentage

4.00%

4.000% Senior Notes Due 2022 | Issuer

Debt Instrument [Line Items]

Principal Issuances

$ 1,000,000,000

$ 500,000,000

Interest rate, stated percentage

4.00%

4.00%

4.000% Senior Notes Due 2022 | Affiliated Entity

Debt Instrument [Line Items]

Interest rate, stated percentage

4.00%

4.000% Senior Notes Due 2022 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

$ 977,000,000

Principal Issuances

1,000,000,000

Discount

(23,000,000)

5.125% Senior Notes due 2025

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

498,000,000

Principal Issuances

500,000,000

Issuance costs related to public debt issuance

$ 2,000,000

Interest rate, stated percentage

5.125%

5.125% Senior Notes due 2025 | Issuer

Debt Instrument [Line Items]

Principal Issuances

$ 1,250,000,000

$ 500,000,000

Interest rate, stated percentage

5.125%

5.125%

5.125% Senior Notes due 2025 | Affiliated Entity

Debt Instrument [Line Items]

Interest rate, stated percentage

5.125%

5.125% Senior Notes due 2025 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

$ 1,222,000,000

Principal Issuances

1,250,000,000

Discount

(28,000,000)

5.375% Senior Notes due 2027

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

499,000,000

Principal Issuances

500,000,000

Issuance costs related to public debt issuance

$ 1,000,000

Interest rate, stated percentage

5.375%

5.375% Senior Notes due 2027 | Issuer

Debt Instrument [Line Items]

Principal Issuances

$ 500,000,000

$ 750,000,000

$ 500,000,000

Interest rate, stated percentage

5.375%

5.375%

5.375%

5.375% Senior Notes due 2027 | Affiliated Entity

Debt Instrument [Line Items]

Interest rate, stated percentage

5.375%

5.375% Senior Notes due 2027 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

$ 1,222,000,000

Principal Issuances

1,250,000,000

Discount

$ (28,000,000)

6.288% Senior Reset Notes to affiliates due 2019 | Affiliated Entity

Debt Instrument [Line Items]

Interest rate, stated percentage

6.288%

6.288% Senior Reset Notes to affiliates due 2019 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

$ (1,250,000,000)

Note Redemptions

(1,250,000,000)

Discount

$ 0

Issuance price percentage of face value

103.144%

6.366% Senior Reset Notes to affiliates due 2020 | Affiliated Entity

Debt Instrument [Line Items]

Interest rate, stated percentage

6.366%

6.366% Senior Reset Notes to affiliates due 2020 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

$ (1,250,000,000)

Note Redemptions

(1,250,000,000)

Discount

$ 0

Issuance price percentage of face value

103.183%

5.300% Senior Notes to affiliates due 2021 | Issuer

Debt Instrument [Line Items]

Principal Issuances

$ 2,000,000,000

Interest rate, stated percentage

5.30%

5.300% Senior Notes to affiliates due 2021 | Affiliated Entity

Debt Instrument [Line Items]

Interest rate, stated percentage

5.30%

6.000% Senior Notes to affiliates due 2024 | Issuer

Debt Instrument [Line Items]

Principal Issuances

$ 1,350,000,000

Interest rate, stated percentage

6.00%

6.000% Senior Notes to affiliates due 2024 | Affiliated Entity

Debt Instrument [Line Items]

Interest rate, stated percentage

6.00%

6.000% Senior Notes to affiliates due 2024 | Issuer

Debt Instrument [Line Items]

Principal Issuances

$ 650,000,000

Interest rate, stated percentage

6.00%

6.000% Senior Notes to affiliates due 2024 | Affiliated Entity

Debt Instrument [Line Items]

Interest rate, stated percentage

6.00%

4.500% Senior Notes due 2026 | Issuer | Subsequent Event

Debt Instrument [Line Items]

Principal Issuances

$ 1,000,000,000

$ 1,000,000,000

Interest rate, stated percentage

4.50%

4.50%

4.500% Senior Notes due 2026 | Affiliated Entity | Issuer | Subsequent Event

Debt Instrument [Line Items]

Principal Issuances

$ 1,000,000,000

Interest rate, stated percentage

4.50%

4.750% Senior Notes due 2028 | Issuer | Subsequent Event

Debt Instrument [Line Items]

Principal Issuances

$ 1,500,000,000

$ 1,500,000,000

Interest rate, stated percentage

4.75%

4.75%

4.750% Senior Notes due 2028 | Affiliated Entity | Issuer | Subsequent Event

Debt Instrument [Line Items]

Principal Issuances

$ 1,500,000,000

Interest rate, stated percentage

4.75%

8.097% Senior Reset Notes to affiliates due 2021 | Affiliated Entity

Debt Instrument [Line Items]

Interest rate, stated percentage

8.097%

8.097% Senior Reset Notes to affiliates due 2021 | Affiliated Entity | Issuer | Scenario, Forecast

Debt Instrument [Line Items]

Principal Issuances

$ 1,250,000,000

Interest rate, stated percentage

8.097%

8.195% Senior Reset Notes to affiliates due 2022 | Affiliated Entity

Debt Instrument [Line Items]

Interest rate, stated percentage

8.195%

8.195% Senior Reset Notes to affiliates due 2022 | Affiliated Entity | Issuer | Scenario, Forecast

Debt Instrument [Line Items]

Principal Issuances

$ 1,250,000,000

Interest rate, stated percentage

8.195%

Senior Notes

Debt Instrument [Line Items]

Write-off of Discounts and Issuance Costs

$ (115,000,000)

Note Redemptions

(8,250,000,000)

Senior Notes | Affiliated Entity

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

4,000,000,000

Extinguishments

(1,980,000,000)

Write-off of Discounts and Issuance Costs

13,000,000

Senior Notes | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

4,064,000,000

Principal Issuances

4,000,000,000

$ 3,000,000,000

$ 3,500,000,000

Premium

64,000,000

Senior Notes | LIBOR plus 2.00% Senior Secured Term Loan due 2022 | Affiliated Entity

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

2,000,000,000

Extinguishments

0

Write-off of Discounts and Issuance Costs

0

Senior Notes | LIBOR plus 2.00% Senior Secured Term Loan due 2024 | Affiliated Entity

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

2,000,000,000

Extinguishments

0

Write-off of Discounts and Issuance Costs

0

Senior Notes | LIBOR plus 2.750% Senior Secured Term Loan | Affiliated Entity

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

0

Extinguishments

(1,980,000,000)

Write-off of Discounts and Issuance Costs

$ 13,000,000

Senior Notes | 4.000% Senior Notes Due 2022 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Interest rate, stated percentage

4.00%

Senior Notes | 5.125% Senior Notes due 2025 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Interest rate, stated percentage

5.125%

Senior Notes | 5.375% Senior Notes due 2027 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Principal Issuances

$ 500,000,000

750,000,000

Interest rate, stated percentage

5.375%

Senior Notes | 6.288% Senior Reset Notes to affiliates due 2019 | Affiliated Entity

Debt Instrument [Line Items]

Principal Issuances

$ 1,250,000,000

Interest rate, stated percentage

6.288%

Senior Notes | 6.288% Senior Reset Notes to affiliates due 2019 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Interest rate, stated percentage

6.288%

Senior Notes | 6.366% Senior Reset Notes to affiliates due 2020 | Affiliated Entity

Debt Instrument [Line Items]

Principal Issuances

$ 1,250,000,000

Interest rate, stated percentage

6.366%

Senior Notes | 6.366% Senior Reset Notes to affiliates due 2020 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Interest rate, stated percentage

6.366%

Senior Notes | 5.300% Senior Notes to affiliates due 2021

Debt Instrument [Line Items]

Interest rate, stated percentage

5.30%

Senior Notes | 5.300% Senior Notes to affiliates due 2021 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

$ 2,000,000,000

Principal Issuances

2,000,000,000

Premium

$ 0

Senior Notes | 6.000% Senior Notes to affiliates due 2024

Debt Instrument [Line Items]

Interest rate, stated percentage

6.00%

Senior Notes | 6.000% Senior Notes to affiliates due 2024 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

$ 1,390,000,000

Principal Issuances

1,350,000,000

Premium

$ 40,000,000

Senior Notes | 6.000% Senior Notes to affiliates due 2024

Debt Instrument [Line Items]

Interest rate, stated percentage

6.00%

Senior Notes | 6.000% Senior Notes to affiliates due 2024 | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Net Proceeds from Issuance of Long-Term Debt

$ 674,000,000

Principal Issuances

650,000,000

Premium

24,000,000

Senior Notes | 4.500% Senior Notes due 2026 | Affiliated Entity | Deutsche Telekom AG | Subsequent Event

Debt Instrument [Line Items]

Principal Issuances

$ 1,000,000,000

Interest rate, stated percentage

4.50%

Senior Notes | 4.750% Senior Notes due 2028 | Affiliated Entity | Deutsche Telekom AG | Subsequent Event

Debt Instrument [Line Items]

Principal Issuances

$ 1,500,000,000

Interest rate, stated percentage

4.75%

Secured Debt

Debt Instrument [Line Items]

Senior Secured Term Loans

$ 0

1,980,000,000

Secured Debt | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Incremental term loan commitment

2,000,000,000

$ 660,000,000

Debt instrument, additional debt capacity

$ 2,000,000,000

Senior Reset Notes | Affiliated Entity | Deutsche Telekom AG

Debt Instrument [Line Items]

Principal Issuances

$ 2,500,000,000

Discount

$ (79,000,000)

Debt - Capital Leases (Details)

Debt - Capital Leases (Details) $ in Millions	Dec. 31, 2017USD ($)
Debt Disclosure [Abstract]
2,018	$ 682
2,019	634
2,020	338
2,021	151
2,022	67
Thereafter	172
Total	2,044
Included in Total
Interest	169
Maintenance	$ 51

Debt - Financing Arrangements (

Debt - Financing Arrangements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Short-term Debt [Line Items]
Proceeds from borrowings under financing arrangement	$ 2,910,000,000	$ 0	$ 0
Repayments of borrowings under financing arrangement	300,000,000	150,000,000	$ 564,000,000
Handset Financing Arrangement
Short-term Debt [Line Items]
Borrowing capacity	108,000,000
Proceeds from borrowings under financing arrangement		100,000,000
Repayments of borrowings under financing arrangement		100,000,000
Short-term debt, outstanding	0	0
Vendor Financing Arrangement
Short-term Debt [Line Items]
Proceeds from borrowings under financing arrangement	300,000,000
Repayments of borrowings under financing arrangement	300,000,000
Short-term debt, outstanding	$ 0	$ 0

Debt - Revolving Credit Facilit

Debt - Revolving Credit Facility and Standby Letters of Credit (Details) - USD ($)	1 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Feb. 05, 2018	Jan. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Letters of credit, amount outstanding	$ 74,000,000	$ 74,000,000			$ 79,000,000
JP Morgan Chase
Debt Instrument [Line Items]
Letters of credit, amount outstanding	20,000,000	20,000,000			20,000,000
Deutsche Bank
Debt Instrument [Line Items]
Letters of credit, amount outstanding	54,000,000	54,000,000			59,000,000
Senior Notes
Debt Instrument [Line Items]
Principal Amount					8,250,000,000
Revolving Credit Facility [$0.5B] | Affiliated Entity
Debt Instrument [Line Items]
Incremental term loan commitment	500,000,000	500,000,000
Unsecured revolving credit facility	(500,000,000)
Revolving Credit Facility [$2.5B] | Affiliated Entity
Debt Instrument [Line Items]
Revolving credit facility	2,500,000,000	2,500,000,000
Revolving Credit Facility [$2.5B] | Affiliated Entity | Unsecured Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility	$ 1,000,000,000	$ 1,000,000,000
Revolving credit agreement term		3 years
Revolving Credit Facility [$2.5B] | Affiliated Entity | Unsecured Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Applicable margin, percentage	2.00%	2.00%
Revolving Credit Facility [$2.5B] | Affiliated Entity | Unsecured Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Applicable margin, percentage	3.25%	3.25%
Revolving Credit Facility [$2.5B] | Affiliated Entity | Secured Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Applicable margin, percentage	1.00%	1.00%
Revolving Credit Facility [$2.5B] | Affiliated Entity | Secured Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Applicable margin, percentage	1.75%	1.75%
Revolving Credit Facility [$2.5B] | Affiliated Entity | Secured Revolving Credit Facility | Line of Credit | Deutsche Telekom AG
Debt Instrument [Line Items]
Short-term debt to affiliates					$ 0
Revolving Credit Facility [$2.5B] | Affiliated Entity | Secured Revolving Credit Facility | Line of Credit | Deutsche Telekom AG | Subsequent Event
Debt Instrument [Line Items]
Short-term debt to affiliates			$ 0
Revolving Credit Facility [$1.5B] | Affiliated Entity | Secured Revolving Credit Facility | Line of Credit | Deutsche Telekom AG
Debt Instrument [Line Items]
Incremental term loan commitment	$ 1,500,000,000	$ 1,500,000,000
Revolving credit agreement term		3 years
Short-term debt to affiliates	$ 0	$ 0
6.125% Senior Notes due 2022
Debt Instrument [Line Items]
Interest rate, stated percentage					6.125%
6.125% Senior Notes due 2022 | Senior Notes | Subsequent Event
Debt Instrument [Line Items]
Principal Amount				$ 1,000,000,000
Interest rate, stated percentage				6.125%

Tower Obligations - Narrative (

Tower Obligations - Narrative (Details) $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2012USD ($)	Dec. 31, 2017	Dec. 31, 2015USD ($)
Tower Transaction
Sale Leaseback Transaction [Line Items]
Property subject to sale, number of units	7,100
Net proceeds, financing activities	$ 2,500
Property subject to failed sale leaseback transaction, number of units	6,200
Lessee leasing arrangements, operating leases, term of contract	10 years	10 years
Sale leaseback transaction, fixed-price purchase options	$ 2,000
Imputed interest rate, financial obligation	8.00%
Tower Transaction | Minimum
Sale Leaseback Transaction [Line Items]
Lessee leasing arrangements, operating leases, term of contract	23 years
Tower Transaction | Maximum
Sale Leaseback Transaction [Line Items]
Lessee leasing arrangements, operating leases, term of contract	37 years
Tower Transaction PTI
Sale Leaseback Transaction [Line Items]
Property subject to sale, number of units			600
Net proceeds, financing activities			$ 140
Property subject to failed sale leaseback transaction, number of units		200
Imputed interest rate, financial obligation			5.00%

Tower Obligations - Sale Leaseb

Tower Obligations - Sale Leaseback Transaction (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Leases [Abstract]
Property and equipment, net	$ 402	$ 485
Long-term financial obligation	$ 2,590	$ 2,621

Tower Obligations - Future Mini

Tower Obligations - Future Minimum Payments (Details) $ in Millions	Dec. 31, 2017USD ($)
Leases [Abstract]
Tower obligation payments, due 2018	$ 189
Tower obligation payments, due 2019 and 2020	379
Tower obligation payments, due 2021 and 2022	381
Tower obligation payments due thereafter	$ 1,000

Employee Compensation and Ben70

Employee Compensation and Benefit Plans - Stock Awards (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 306	$ 235	$ 201
Income tax benefit related to stock-based compensation	73	80	71
RSU and PSU Weighted Average Grant-Date Fair Value
Taxes paid related to net share settlement of stock awards	$ 166	$ 121	$ 156
Restricted Stock Units and Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value per stock award granted (usd per share)	$ 60.21	$ 45.07	$ 35.56
Unrecognized compensation expense	$ 445	$ 389	$ 327
Weighted average period to be recognized (years)	1 year 11 months	2 years	2 years
Fair value of stock awards vested	$ 503	$ 354	$ 445
RSU and PSU Shares
Nonvested, beginning (in shares)	15,715,391
Granted (in shares)	7,133,359
Vested (in shares)	(8,338,271)
Forfeited (in shares)	(814,936)
Nonvested, ending (in shares)	13,695,543	15,715,391
RSU and PSU Weighted Average Grant-Date Fair Value
Nonvested, beginning (usd per share)	$ 37.93
Granted (usd per share)	60.21	$ 45.07	$ 35.56
Vested (usd per share)	35.47
Forfeited (usd per share)	49.02
Nonvested, ending (usd per share)	$ 50.38	$ 37.93
Weighted Average Remaining Contractual Term (Years)	1 year 1 month	1 year 1 month
Aggregate Intrinsic Value	$ 870	$ 904
Share paid for tax withholding for share based compensation (in shares)	2,754,721	2,605,807
Minimum
RSU and PSU Weighted Average Grant-Date Fair Value
Share payout percentage	0.00%
Maximum
RSU and PSU Weighted Average Grant-Date Fair Value
Share payout percentage	200.00%
Maximum | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years
Maximum | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years
2013 Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance (in shares)	63,000,000
Shares available for future grant (in shares)	15,000,000
Predecessor Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Realized excess tax benefit	$ 0	$ 0	$ 79

Employee Compensation and Ben71

Employee Compensation and Benefit Plans - Employee Stock Purchase Plan (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Contribution percentage (up to)	15.00%
Stock purchase discount percentage	15.00%
ESPP, offering period	6 months
Common Stock
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Number of shares issued under ESPP (in shares)	1,832,043	1,905,534	761,085

Employee Compensation and Ben72

Employee Compensation and Benefit Plans - Stock Options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Proceeds from exercise of stock options	$ 21	$ 29	$ 47
Predecessor Plans
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding and exercisable, beginning (in shares)	833,931
Exercised (in shares)	(450,873)
Expired (in shares)	(9,900)
Outstanding and exercisable, ending (in shares)	373,158	833,931
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding and exercisable, beginning (usd per share)	$ 31.75
Exercised (usd per share)	44.18
Expired (usd per share)	45.76
Outstanding and exercisable, ending (usd per share)	$ 16.36	$ 31.75
Weighted Average Remaining Contractual Term (Years)	2 years 9 months	2 years 4 months
Proceeds from exercise of stock options	$ 21	$ 29

Employee Compensation and Ben73

Employee Compensation and Benefit Plans - Employee Retirement Savings and Compensation Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Employer retirement savings plan, matching contributions	$ 87	$ 83	$ 73
Long Term Incentive Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Compensation expense	0	0	27
Payments	$ 0	$ 52	$ 57

Repurchases of Common Stock - N

Repurchases of Common Stock - Narrative (Details) - USD ($)	2 Months Ended	12 Months Ended
	Feb. 05, 2018	Dec. 31, 2017	Dec. 06, 2017
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount			$ 1,500,000,000
Number of Shares Repurchased		7,010,889
Total Purchase Price		$ 444,000,000
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Number of Shares Repurchased	12,300,000
Average Price Paid Per Share (usd per share)	$ 63.68
Total Purchase Price	$ 783,000,000
Repurchase authority remaining	$ 717,000,000

Repurchases of Common Stock - S

Repurchases of Common Stock - Schedule of Repurchases of Common Stock (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Equity [Abstract]
Number of Shares Repurchased | shares	7,010,889
Average Price Paid Per Share (usd per share) | $ / shares	$ 63.34
Total Purchase Price | $	$ 444

Income Taxes - Income Tax Domes

Income Taxes - Income Tax Domestic and Foreign (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S.	$ 3,274	$ 2,286	$ 898
Puerto Rico	(113)	41	80
Income before income taxes	$ 3,161	$ 2,327	$ 978

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current tax benefit (expense)
Federal	$ 0	$ 66	$ 30
State	(28)	(29)	(2)
Puerto Rico	(1)	10	(17)
Total current tax benefit (expense)	(29)	47	11
Deferred tax benefit (expense)
Federal	1,182	(804)	(281)
State	173	(96)	37
Puerto Rico	49	(14)	(12)
Total deferred tax benefit (expense)	1,404	(914)	(256)
Total income tax benefit (expense)	$ 1,375	$ (867)	$ (245)

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory income tax rate	35.00%	35.00%	35.00%
Effect of the Tax Cuts and Jobs Act	(68.90%)	0.00%	0.00%
Change in valuation allowance	(11.40%)	1.00%	(3.20%)
State taxes, net of federal benefit	4.80%	4.00%	(1.10%)
Equity-based compensation	(2.40%)	(2.20%)	0.00%
Puerto Rico taxes, net of federal benefit	(1.50%)	0.00%	3.30%
Permanent differences	0.50%	0.60%	1.60%
Federal tax credits, net of reserves	0.30%	(0.50%)	(9.50%)
Other, net	0.10%	(0.60%)	(1.00%)
Effective income tax rate	(43.50%)	37.30%	25.10%

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets
Loss carryforwards	$ 1,576	$ 1,442
Deferred rents	759	1,153
Reserves and accruals	667	1,058
Federal and state tax credits	298	284
Debt fair market value adjustment	0	83
Other	403	430
Deferred tax assets, gross	3,703	4,450
Valuation allowance	(273)	(573)
Deferred tax assets, net	3,430	3,877
Deferred tax liabilities
Spectrum licenses	5,038	6,952
Property and equipment	1,840	1,732
Other intangible assets	41	119
Other	48	12
Total deferred tax liabilities	6,967	8,815
Net deferred tax liabilities	3,537	4,938
Deferred tax liabilities	$ 3,537	$ 4,938

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Net tax benefit associated with enactment of the TCJA	$ 2,200
Alternative minimum tax credit carryforward	86	$ 86
Foreign tax credits	298	298	$ 284
Valuation allowance	(273)	(273)	$ (573)
Net tax benefits		359
Valuation allowance established for impact of TCJA	26	26
Valuation allowance no longer necessary as a result of certain state jurisdictions		319
Reduced Federal Benefit of State Items
Operating Loss Carryforwards [Line Items]
Valuation allowance, change in amount		33
Federal
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits, net operating loss	1,000	1,000
Operating loss carryforwards	123	123
Federal | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Foreign tax credits	198	198
State
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits, net operating loss	832	832
Operating loss carryforwards	$ 242	$ 242

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning of year	$ 410	$ 411	$ 388
Gross decreases to tax positions in prior periods	(10)	(5)	(112)
Gross increases to current period tax positions	12	4	135
Unrecognized tax benefits, end of year	412	410	$ 411
Unrecognized tax benefits that would impact effective tax rate	$ 254	$ 168

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income	$ 2,707	$ 550	$ 581	$ 698	$ 390	$ 366	$ 225	$ 479	$ 4,536	$ 1,460	$ 733
Less: Dividends on mandatory convertible preferred stock	(14)	(13)	(14)	(14)	(14)	(13)	(14)	(14)	(55)	(55)	(55)
Net income attributable to common stockholders	$ 2,693	$ 537	$ 567	$ 684	$ 376	$ 353	$ 211	$ 465	4,481	1,405	678
Add: Dividends related to mandatory convertible preferred stock									55	0	0
Net income attributable to common stockholders - diluted									$ 4,536	$ 1,405	$ 678
Weighted average shares outstanding - basic (in shares)	837,416,683	831,189,779	830,971,528	827,723,034	824,982,734	822,998,697	822,434,490	819,431,761	831,850,073	822,470,275	812,994,028
Outstanding stock options and unvested stock awards (in shares)									9,200,873	10,584,270	9,623,910
Mandatory convertible preferred stock (in shares)									30,736,504	0	0
Weighted average shares outstanding - diluted (in shares)	871,501,578	871,420,065	870,456,447	869,395,250	867,262,400	832,257,819	829,752,956	859,382,827	871,787,450	833,054,545	822,617,938
Earnings per share - basic (in USD per share)	$ 3.22	$ 0.65	$ 0.68	$ 0.83	$ 0.46	$ 0.43	$ 0.26	$ 0.57	$ 5.39	$ 1.71	$ 0.83
Earnings per share - diluted (in USD per share)	$ 3.11	$ 0.63	$ 0.67	$ 0.80	$ 0.45	$ 0.42	$ 0.25	$ 0.56	$ 5.20	$ 1.69	$ 0.82
Outstanding stock options and unvested stock awards (in shares)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)									33,980	3,528,683	4,842,370
Mandatory convertible preferred stock (in shares)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)									0	32,238,000	32,238,000

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details)	Dec. 15, 2017shares
Class of Stock [Line Items]
Shares issued upon conversion	20,000,000
Common Stock
Class of Stock [Line Items]
Shares issued upon conversion	1.6119
Issuance of stock, shares	32,238,000

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions	Jan. 22, 2018	Jan. 01, 2018	Feb. 28, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Leased Assets [Line Items]
Operating leases, due 2018					$ 2,400
Operating leases, total due 2019 and 2020					4,100
Operating leases, total due 2021 and 2022					2,700
Operating leases total due thereafter					2,300
Rent expense under operating leases					2,900	$ 2,800	$ 2,800
Purchase obligation, due 2018					2,100
Purchase obligation, due 2019 and 2020					2,200
Purchase obligation, due 2021 and 2022					1,500
Purchase obligation total due thereafter					$ 1,000
Iowa Wireless
Operating Leased Assets [Line Items]
Unconsolidated subsidiary ownership percentage				54.00%
Purchase price of unconsolidated subsidiary				$ 25
Scenario, Forecast
Operating Leased Assets [Line Items]
Increase in minimum lease payments			$ 400
Subsequent Event | Iowa Wireless
Operating Leased Assets [Line Items]
Unconsolidated subsidiary ownership percentage		54.00%
Purchase price of unconsolidated subsidiary		$ 25
Subsequent Event | Layer3 TV
Operating Leased Assets [Line Items]
Purchase price of wholly-owned consolidated subsidiary	$ 325
Cell Sites | Minimum
Operating Leased Assets [Line Items]
Initial non-cancelable term					5 years
Cell Sites | Maximum
Operating Leased Assets [Line Items]
Initial non-cancelable term					10 years

Additional Financial Informat85

Additional Financial Information - Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Supplemental Financial Statement Elements [Abstract]
Accounts payable	$ 6,182	$ 5,163
Payroll and related benefits	614	559
Property and other taxes, including payroll	620	525
Interest	253	423
Commissions	324	159
Network decommissioning	92	101
Toll and interconnect	109	85
Advertising	46	44
Other	288	93
Accounts payable and accrued liabilities	8,528	7,152
Accounts Payable and Accrued Liabilities
Accounts Payable and Accrued Liabilities [Line Items]
Outstanding checks	$ 455	$ 356

Additional Financial Informat86

Additional Financial Information - Narrative (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant Transactions [Line Items]
Operating income	$ 1,112	$ 1,323	$ 1,416	$ 1,037	$ 1,001	$ 1,048	$ 833	$ 1,168	$ 4,888	$ 4,050	$ 2,479
Hurricane
Significant Transactions [Line Items]
Operating income									(201)
Insurance recoveries related to hurricane losses									$ (93)

Additional Financial Informat87

Additional Financial Information - Related Party Transactions (Details) - Affiliated Entity - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Discount related to roaming expenses	$ 0	$ (15)	$ (21)
Fees incurred for use of the T-Mobile brand	79	74	65
Expenses for telecommunications and IT services	12	25	23
International long distance agreement	55	60	0
Reimbursement of certain administrative expenses	$ 11	$ 11	$ 2

Subsequent Events - Narrative (

Subsequent Events - Narrative (Details) - USD ($)	Jan. 22, 2018	Jan. 01, 2018	Sep. 30, 2017	Jan. 31, 2018	Jan. 25, 2018	Dec. 31, 2017	Apr. 30, 2017	Mar. 16, 2017	Mar. 13, 2017
Subsequent Event [Line Items]
Principal Issuances						$ 1,500,000,000		$ 1,500,000,000
Affiliated Entity | Deutsche Telekom AG
Subsequent Event [Line Items]
Principal Issuances						1,000,000,000
Senior Notes
Subsequent Event [Line Items]
Redemption of aggregate principal amount						8,250,000,000
Senior Notes | Affiliated Entity | Deutsche Telekom AG
Subsequent Event [Line Items]
Principal Issuances						$ 4,000,000,000	$ 3,000,000,000		$ 3,500,000,000
6.125% Senior Notes due 2022
Subsequent Event [Line Items]
Interest rate, stated percentage						6.125%
Iowa Wireless
Subsequent Event [Line Items]
Unconsolidated subsidiary ownership percentage			54.00%
Purchase price of unconsolidated subsidiary			$ 25,000,000
Subsequent Event | 6.125% Senior Notes due 2022 | Senior Notes
Subsequent Event [Line Items]
Redemption of aggregate principal amount				$ 1,000,000,000
Interest rate, stated percentage				6.125%
Subsequent Event | 4.500% Senior Notes due 2026 | Issuer
Subsequent Event [Line Items]
Interest rate, stated percentage				4.50%	4.50%
Principal Issuances				$ 1,000,000,000	$ 1,000,000,000
Subsequent Event | 4.500% Senior Notes due 2026 | Affiliated Entity | Issuer
Subsequent Event [Line Items]
Interest rate, stated percentage	4.50%
Principal Issuances	$ 1,000,000,000
Subsequent Event | 4.500% Senior Notes due 2026 | Senior Notes | Affiliated Entity | Deutsche Telekom AG
Subsequent Event [Line Items]
Interest rate, stated percentage				4.50%
Principal Issuances				$ 1,000,000,000
Subsequent Event | 4.750% Senior Notes due 2028 | Issuer
Subsequent Event [Line Items]
Interest rate, stated percentage				4.75%	4.75%
Principal Issuances				$ 1,500,000,000	$ 1,500,000,000
Subsequent Event | 4.750% Senior Notes due 2028 | Affiliated Entity | Issuer
Subsequent Event [Line Items]
Interest rate, stated percentage	4.75%
Principal Issuances	$ 1,500,000,000
Subsequent Event | 4.750% Senior Notes due 2028 | Senior Notes | Affiliated Entity | Deutsche Telekom AG
Subsequent Event [Line Items]
Interest rate, stated percentage				4.75%
Principal Issuances				$ 1,500,000,000
Subsequent Event | Iowa Wireless
Subsequent Event [Line Items]
Unconsolidated subsidiary ownership percentage		54.00%
Purchase price of unconsolidated subsidiary		$ 25,000,000
Subsequent Event | Layer3 TV
Subsequent Event [Line Items]
Purchase price of wholly-owned consolidated subsidiary	$ 325,000,000

Guarantor Financial Informati89

Guarantor Financial Information - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	May 31, 2017	Apr. 30, 2017	Mar. 31, 2017	Mar. 16, 2017	Jan. 31, 2017	Jan. 25, 2017
Condensed Financial Statements, Captions [Line Items]
Long-term debt	$ 1,500,000,000							$ 1,500,000,000
Net cash provided by (used in) operating activities	7,962,000,000	$ 6,135,000,000	$ 5,414,000,000
Net cash (used in) provided by financing activities	(1,179,000,000)	463,000,000	3,413,000,000
Issuer | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(1,613,000,000)	(1,335,000,000)	(1,147,000,000)
Net cash (used in) provided by financing activities	(1,119,000,000)	301,000,000	2,667,000,000
Issuer | Reportable Legal Entities | Reclassification Adjustment
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		696,000,000	3,400,000,000
Net cash (used in) provided by financing activities		(696,000,000)	(3,400,000,000)
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	9,616,000,000	7,541,000,000	6,652,000,000
Net cash (used in) provided by financing activities	192,000,000	117,000,000	2,576,000,000
Guarantor Subsidiaries | Reportable Legal Entities | Reclassification Adjustment
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		625,000,000	3,300,000,000
Net cash (used in) provided by financing activities		(625,000,000)	(3,300,000,000)
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	58,000,000	33,000,000	85,000,000
Net cash (used in) provided by financing activities	(67,000,000)	(39,000,000)	(106,000,000)
Non-Guarantor Subsidiaries | Reportable Legal Entities | Reclassification Adjustment
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities		71,000,000	69,000,000
Net cash (used in) provided by financing activities		$ (71,000,000)	$ (69,000,000)
Incremental Term Loan Facility
Condensed Financial Statements, Captions [Line Items]
Long-term debt									$ 4,000,000,000
Refinanced Secured Term Loans
Condensed Financial Statements, Captions [Line Items]
Senior Secured Term Loans									$ 1,980,000,000
Refinanced Secured Term Loans | Affiliated Entity
Condensed Financial Statements, Captions [Line Items]
Senior Secured Term Loans										$ 1,980,000,000
4.000% Senior Notes Due 2022
Condensed Financial Statements, Captions [Line Items]
Long-term debt	$ 500,000,000
Interest rate, stated percentage	4.00%
4.000% Senior Notes Due 2022 | Issuer
Condensed Financial Statements, Captions [Line Items]
Long-term debt						$ 1,000,000,000	$ 500,000,000
Interest rate, stated percentage						4.00%	4.00%
4.000% Senior Notes Due 2022 | Affiliated Entity
Condensed Financial Statements, Captions [Line Items]
Interest rate, stated percentage	4.00%
5.125% Senior Notes due 2025
Condensed Financial Statements, Captions [Line Items]
Long-term debt	$ 500,000,000
Interest rate, stated percentage	5.125%
5.125% Senior Notes due 2025 | Issuer
Condensed Financial Statements, Captions [Line Items]
Long-term debt						$ 1,250,000,000	$ 500,000,000
Interest rate, stated percentage						5.125%	5.125%
5.125% Senior Notes due 2025 | Affiliated Entity
Condensed Financial Statements, Captions [Line Items]
Interest rate, stated percentage	5.125%
5.375% Senior Notes due 2027
Condensed Financial Statements, Captions [Line Items]
Long-term debt	$ 500,000,000
Interest rate, stated percentage	5.375%
5.375% Senior Notes due 2027 | Issuer
Condensed Financial Statements, Captions [Line Items]
Long-term debt				$ 500,000,000		$ 750,000,000	$ 500,000,000
Interest rate, stated percentage				5.375%		5.375%	5.375%
5.375% Senior Notes due 2027 | Affiliated Entity
Condensed Financial Statements, Captions [Line Items]
Interest rate, stated percentage	5.375%
6.288% Senior Reset Notes to affiliates due 2019 | Affiliated Entity
Condensed Financial Statements, Captions [Line Items]
Interest rate, stated percentage	6.288%
6.288% Senior Reset Notes to affiliates due 2019 | Senior Notes | Affiliated Entity
Condensed Financial Statements, Captions [Line Items]
Long-term debt						$ 1,250,000,000
Interest rate, stated percentage						6.288%
6.366% Senior Reset Notes to affiliates due 2020 | Affiliated Entity
Condensed Financial Statements, Captions [Line Items]
Interest rate, stated percentage	6.366%
6.366% Senior Reset Notes to affiliates due 2020 | Senior Notes | Affiliated Entity
Condensed Financial Statements, Captions [Line Items]
Long-term debt						$ 1,250,000,000
Interest rate, stated percentage						6.366%
5.300% Senior Notes to affiliates due 2021 | Issuer
Condensed Financial Statements, Captions [Line Items]
Long-term debt					$ 2,000,000,000
Interest rate, stated percentage					5.30%
5.300% Senior Notes to affiliates due 2021 | Affiliated Entity
Condensed Financial Statements, Captions [Line Items]
Interest rate, stated percentage	5.30%
5.300% Senior Notes to affiliates due 2021 | Senior Notes
Condensed Financial Statements, Captions [Line Items]
Interest rate, stated percentage	5.30%
6.000% Senior Notes to affiliates due 2024 | Issuer
Condensed Financial Statements, Captions [Line Items]
Long-term debt					$ 1,350,000,000
Interest rate, stated percentage					6.00%
6.000% Senior Notes to affiliates due 2024 | Affiliated Entity
Condensed Financial Statements, Captions [Line Items]
Interest rate, stated percentage	6.00%
6.000% Senior Notes to affiliates due 2024 | Senior Notes
Condensed Financial Statements, Captions [Line Items]
Interest rate, stated percentage	6.00%
6.000% Senior Notes to affiliates due 2024 | Issuer
Condensed Financial Statements, Captions [Line Items]
Long-term debt					$ 650,000,000
Interest rate, stated percentage					6.00%
6.000% Senior Notes to affiliates due 2024 | Affiliated Entity
Condensed Financial Statements, Captions [Line Items]
Interest rate, stated percentage	6.00%
6.000% Senior Notes to affiliates due 2024 | Senior Notes
Condensed Financial Statements, Captions [Line Items]
Interest rate, stated percentage	6.00%

Guarantor Financial Informati90

Guarantor Financial Information - Condensed Consolidating Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 1,219	$ 5,500	$ 4,582	$ 5,315
Accounts receivable, net	1,915	1,896
Equipment installment plan receivables, net	2,290	1,930
Accounts receivable from affiliates	22	40
Inventories	1,566	1,111
Asset purchase deposit	0	2,203
Other current assets	1,903	1,537
Total current assets	8,915	14,217
Property and equipment, net	22,196	20,943
Goodwill	1,683	1,683
Spectrum licenses	35,366	27,014
Other intangible assets, net	217	376
Investments in subsidiaries, net	0	0
Intercompany receivables and note receivables	0	0
Equipment installment plan receivables due after one year, net	1,274	984
Other assets	912	674
Total assets	70,563	65,891
Current liabilities
Accounts payable and accrued liabilities	8,528	7,152
Payables to affiliates	182	125
Short-term debt	1,612	354
Deferred revenue	779	986
Other current liabilities	414	405
Total current liabilities	11,515	9,022
Long-term debt	12,121	21,832
Long-term debt to affiliates	14,586	5,600
Tower obligations	2,590	2,621
Deferred tax liabilities	3,537	4,938
Deferred rent expense	2,720	2,616
Negative carrying value of subsidiaries, net	0	0
Intercompany payables and debt	0	0
Other long-term liabilities	935	1,026
Total long-term liabilities	36,489	38,633
Total stockholders' equity (deficit)	22,559	18,236	16,557	15,663
Total liabilities and stockholders' equity	70,563	65,891
Consolidating and Eliminating Adjustments
Current assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0
Equipment installment plan receivables, net	0	0
Accounts receivable from affiliates	0	0
Inventories	0	0
Asset purchase deposit		0
Other current assets	0	0
Total current assets	0	0
Property and equipment, net	0	0
Goodwill	0	0
Spectrum licenses	0	0
Other intangible assets, net	0	0
Investments in subsidiaries, net	(63,522)	(52,777)
Intercompany receivables and note receivables	(8,503)	(7,022)
Equipment installment plan receivables due after one year, net	0	0
Other assets	(140)	(195)
Total assets	(72,165)	(59,994)
Current liabilities
Accounts payable and accrued liabilities	0	0
Payables to affiliates	0	0
Short-term debt	0	0
Deferred revenue	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Long-term debt	0	0
Long-term debt to affiliates	0	0
Tower obligations	0	0
Deferred tax liabilities	(140)	(195)
Deferred rent expense	0	0
Negative carrying value of subsidiaries, net	(629)	(568)
Intercompany payables and debt	(8,503)	(7,022)
Other long-term liabilities	0	0
Total long-term liabilities	(9,272)	(7,785)
Total stockholders' equity (deficit)	(62,893)	(52,209)
Total liabilities and stockholders' equity	(72,165)	(59,994)
Parent | Reportable Legal Entities
Current assets
Cash and cash equivalents	74	358	378	2,278
Accounts receivable, net	0	0
Equipment installment plan receivables, net	0	0
Accounts receivable from affiliates	0	0
Inventories	0	0
Asset purchase deposit		0
Other current assets	0	0
Total current assets	74	358
Property and equipment, net	0	0
Goodwill	0	0
Spectrum licenses	0	0
Other intangible assets, net	0	0
Investments in subsidiaries, net	22,534	17,682
Intercompany receivables and note receivables	0	196
Equipment installment plan receivables due after one year, net	0	0
Other assets	0	0
Total assets	22,608	18,236
Current liabilities
Accounts payable and accrued liabilities	0	0
Payables to affiliates	0	0
Short-term debt	0	0
Deferred revenue	0	0
Other current liabilities	17	0
Total current liabilities	17	0
Long-term debt	0	0
Long-term debt to affiliates	0	0
Tower obligations	0	0
Deferred tax liabilities	0	0
Deferred rent expense	0	0
Negative carrying value of subsidiaries, net	0	0
Intercompany payables and debt	32	0
Other long-term liabilities	0	0
Total long-term liabilities	32	0
Total stockholders' equity (deficit)	22,559	18,236
Total liabilities and stockholders' equity	22,608	18,236
Issuer | Reportable Legal Entities
Current assets
Cash and cash equivalents	1	2,733	1,767	2,246
Accounts receivable, net	0	0
Equipment installment plan receivables, net	0	0
Accounts receivable from affiliates	0	0
Inventories	0	0
Asset purchase deposit		0
Other current assets	0	0
Total current assets	1	2,733
Property and equipment, net	0	0
Goodwill	0	0
Spectrum licenses	0	0
Other intangible assets, net	0	0
Investments in subsidiaries, net	40,988	35,095
Intercompany receivables and note receivables	8,503	6,826
Equipment installment plan receivables due after one year, net	0	0
Other assets	2	7
Total assets	49,494	44,661
Current liabilities
Accounts payable and accrued liabilities	253	423
Payables to affiliates	146	79
Short-term debt	999	20
Deferred revenue	0	0
Other current liabilities	0	0
Total current liabilities	1,398	522
Long-term debt	10,911	20,741
Long-term debt to affiliates	14,586	5,600
Tower obligations	0	0
Deferred tax liabilities	0	0
Deferred rent expense	0	0
Negative carrying value of subsidiaries, net	0	0
Intercompany payables and debt	0	0
Other long-term liabilities	65	116
Total long-term liabilities	25,562	26,457
Total stockholders' equity (deficit)	22,534	17,682
Total liabilities and stockholders' equity	49,494	44,661
Guarantor Subsidiaries | Reportable Legal Entities
Current assets
Cash and cash equivalents	1,086	2,342	2,364	697
Accounts receivable, net	1,659	1,675
Equipment installment plan receivables, net	2,290	1,930
Accounts receivable from affiliates	22	40
Inventories	1,566	1,111
Asset purchase deposit		2,203
Other current assets	1,275	972
Total current assets	7,898	10,273
Property and equipment, net	21,890	20,568
Goodwill	1,683	1,683
Spectrum licenses	35,366	27,014
Other intangible assets, net	217	376
Investments in subsidiaries, net	0	0
Intercompany receivables and note receivables	0	0
Equipment installment plan receivables due after one year, net	1,274	984
Other assets	814	600
Total assets	69,142	61,498
Current liabilities
Accounts payable and accrued liabilities	8,014	6,474
Payables to affiliates	36	46
Short-term debt	613	334
Deferred revenue	779	986
Other current liabilities	192	258
Total current liabilities	9,634	8,098
Long-term debt	1,210	1,091
Long-term debt to affiliates	0	0
Tower obligations	392	400
Deferred tax liabilities	3,677	5,133
Deferred rent expense	2,720	2,616
Negative carrying value of subsidiaries, net	629	568
Intercompany payables and debt	8,201	6,785
Other long-term liabilities	866	906
Total long-term liabilities	17,695	17,499
Total stockholders' equity (deficit)	41,813	35,901
Total liabilities and stockholders' equity	69,142	61,498
Non-Guarantor Subsidiaries | Reportable Legal Entities
Current assets
Cash and cash equivalents	58	67	$ 73	$ 94
Accounts receivable, net	256	221
Equipment installment plan receivables, net	0	0
Accounts receivable from affiliates	0	0
Inventories	0	0
Asset purchase deposit		0
Other current assets	628	565
Total current assets	942	853
Property and equipment, net	306	375
Goodwill	0	0
Spectrum licenses	0	0
Other intangible assets, net	0	0
Investments in subsidiaries, net	0	0
Intercompany receivables and note receivables	0	0
Equipment installment plan receivables due after one year, net	0	0
Other assets	236	262
Total assets	1,484	1,490
Current liabilities
Accounts payable and accrued liabilities	261	255
Payables to affiliates	0	0
Short-term debt	0	0
Deferred revenue	0	0
Other current liabilities	205	147
Total current liabilities	466	402
Long-term debt	0	0
Long-term debt to affiliates	0	0
Tower obligations	2,198	2,221
Deferred tax liabilities	0	0
Deferred rent expense	0	0
Negative carrying value of subsidiaries, net	0	0
Intercompany payables and debt	270	237
Other long-term liabilities	4	4
Total long-term liabilities	2,472	2,462
Total stockholders' equity (deficit)	(1,454)	(1,374)
Total liabilities and stockholders' equity	$ 1,484	$ 1,490

Guarantor Financial Informati91

Guarantor Financial Information - Condensed Consolidating Statement of Comprehensive Income Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues
Service revenues									$ 30,160	$ 27,844	$ 24,821
Equipment revenues									9,375	8,727	6,718
Other revenues									1,069	919	928
Total revenues	$ 10,759	$ 10,019	$ 10,213	$ 9,613	$ 10,234	$ 9,305	$ 9,287	$ 8,664	40,604	37,490	32,467
Operating expenses
Cost of services, exclusive of depreciation and amortization shown separately below									6,100	5,731	5,554
Cost of equipment sales									11,608	10,819	9,344
Selling, general and administrative									12,259	11,378	10,189
Depreciation and amortization									5,984	6,243	4,688
Cost of MetroPCS business combination					(6)	15	59	36	0	104	376
Gains on disposal of spectrum licenses	(168)	(29)	(1)	(37)	0	(199)	0	(636)	(235)	(835)	(163)
Total operating expense									35,716	33,440	29,988
Operating income	1,112	1,323	1,416	1,037	1,001	1,048	833	1,168	4,888	4,050	2,479
Other income (expense)
Interest expense									(1,111)	(1,418)	(1,085)
Interest expense to affiliates									(560)	(312)	(411)
Interest income									17	13	6
Other expense, net									(73)	(6)	(11)
Total other expense, net									(1,727)	(1,723)	(1,501)
Income before income taxes									3,161	2,327	978
Income tax benefit (expense)									1,375	(867)	(245)
Earnings (loss) of subsidiaries									0	0	0
Net income	2,707	550	581	698	390	366	225	479	4,536	1,460	733
Dividends on preferred stock	(14)	(13)	(14)	(14)	(14)	(13)	(14)	(14)	(55)	(55)	(55)
Net income attributable to common stockholders	$ 2,693	$ 537	$ 567	$ 684	$ 376	$ 353	$ 211	$ 465	4,481	1,405	678
Other comprehensive income (loss), net of tax									7	2	(2)
Total comprehensive income									4,543	1,462	731
Consolidating and Eliminating Adjustments
Revenues
Service revenues									(847)	(792)	(596)
Equipment revenues									(245)	(418)	(430)
Other revenues									(25)	(18)	(14)
Total revenues									(1,117)	(1,228)	(1,040)
Operating expenses
Cost of services, exclusive of depreciation and amortization shown separately below									0	0	0
Cost of equipment sales									(244)	(417)	(431)
Selling, general and administrative									(873)	(811)	(609)
Depreciation and amortization									0	0	0
Cost of MetroPCS business combination										0	0
Gains on disposal of spectrum licenses									0	0	0
Total operating expense									(1,117)	(1,228)	(1,040)
Operating income									0	0	0
Other income (expense)
Interest expense									0	0	0
Interest expense to affiliates									23	0	0
Interest income									(23)	0	0
Other expense, net									0	0	0
Total other expense, net									0	0	0
Income before income taxes									0	0	0
Income tax benefit (expense)									0	0	0
Earnings (loss) of subsidiaries									(10,440)	(4,326)	(2,683)
Net income									(10,440)	(4,326)	(2,683)
Dividends on preferred stock									0	0	0
Net income attributable to common stockholders									(10,440)	(4,326)	(2,683)
Other comprehensive income (loss), net of tax									(14)	(6)	4
Total comprehensive income									(10,454)	(4,332)	(2,679)
Parent | Reportable Legal Entities
Revenues
Service revenues									0	0	0
Equipment revenues									0	0	0
Other revenues									0	0	0
Total revenues									0	0	0
Operating expenses
Cost of services, exclusive of depreciation and amortization shown separately below									0	0	0
Cost of equipment sales									0	0	0
Selling, general and administrative									0	0	0
Depreciation and amortization									0	0	0
Cost of MetroPCS business combination										0	0
Gains on disposal of spectrum licenses									0	0	0
Total operating expense									0	0	0
Operating income									0	0	0
Other income (expense)
Interest expense									0	0	0
Interest expense to affiliates									0	0	0
Interest income									1	0	0
Other expense, net									0	0	0
Total other expense, net									1	0	0
Income before income taxes									1	0	0
Income tax benefit (expense)									0	0	0
Earnings (loss) of subsidiaries									4,535	1,460	733
Net income									4,536	1,460	733
Dividends on preferred stock									(55)	(55)	(55)
Net income attributable to common stockholders									4,481	1,405	678
Other comprehensive income (loss), net of tax									7	2	(2)
Total comprehensive income									4,543	1,462	731
Issuer | Reportable Legal Entities
Revenues
Service revenues									0	0	0
Equipment revenues									0	0	0
Other revenues									3	3	1
Total revenues									3	3	1
Operating expenses
Cost of services, exclusive of depreciation and amortization shown separately below									0	0	0
Cost of equipment sales									0	0	0
Selling, general and administrative									0	0	0
Depreciation and amortization									0	0	0
Cost of MetroPCS business combination										0	0
Gains on disposal of spectrum licenses									0	0	0
Total operating expense									0	0	0
Operating income									3	3	1
Other income (expense)
Interest expense									(811)	(1,147)	(847)
Interest expense to affiliates									(560)	(312)	(411)
Interest income									29	31	2
Other expense, net									(88)	2	(10)
Total other expense, net									(1,430)	(1,426)	(1,266)
Income before income taxes									(1,427)	(1,423)	(1,265)
Income tax benefit (expense)									0	0	0
Earnings (loss) of subsidiaries									5,962	2,883	1,998
Net income									4,535	1,460	733
Dividends on preferred stock									0	0	0
Net income attributable to common stockholders									4,535	1,460	733
Other comprehensive income (loss), net of tax									7	2	(2)
Total comprehensive income									4,542	1,462	731
Guarantor Subsidiaries | Reportable Legal Entities
Revenues
Service revenues									28,894	26,613	23,748
Equipment revenues									9,620	9,145	7,148
Other revenues									879	739	770
Total revenues									39,393	36,497	31,666
Operating expenses
Cost of services, exclusive of depreciation and amortization shown separately below									6,076	5,707	5,530
Cost of equipment sales									10,849	10,209	9,055
Selling, general and administrative									12,276	11,321	10,065
Depreciation and amortization									5,914	6,165	4,605
Cost of MetroPCS business combination										104	376
Gains on disposal of spectrum licenses									(235)	(835)	(163)
Total operating expense									34,880	32,671	29,468
Operating income									4,513	3,826	2,198
Other income (expense)
Interest expense									(109)	(82)	(50)
Interest expense to affiliates									(23)	0	0
Interest income									10	(18)	4
Other expense, net									16	(8)	0
Total other expense, net									(106)	(108)	(46)
Income before income taxes									4,407	3,718	2,152
Income tax benefit (expense)									1,527	(857)	(214)
Earnings (loss) of subsidiaries									(57)	(17)	(48)
Net income									5,877	2,844	1,890
Dividends on preferred stock									0	0	0
Net income attributable to common stockholders									5,877	2,844	1,890
Other comprehensive income (loss), net of tax									7	2	(2)
Total comprehensive income									5,884	2,846	1,888
Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenues
Service revenues									2,113	2,023	1,669
Equipment revenues									0	0	0
Other revenues									212	195	171
Total revenues									2,325	2,218	1,840
Operating expenses
Cost of services, exclusive of depreciation and amortization shown separately below									24	24	24
Cost of equipment sales									1,003	1,027	720
Selling, general and administrative									856	868	733
Depreciation and amortization									70	78	83
Cost of MetroPCS business combination										0	0
Gains on disposal of spectrum licenses									0	0	0
Total operating expense									1,953	1,997	1,560
Operating income									372	221	280
Other income (expense)
Interest expense									(191)	(189)	(188)
Interest expense to affiliates									0	0	0
Interest income									0	0	0
Other expense, net									(1)	0	(1)
Total other expense, net									(192)	(189)	(189)
Income before income taxes									180	32	91
Income tax benefit (expense)									(152)	(10)	(31)
Earnings (loss) of subsidiaries									0	0	0
Net income									28	22	60
Dividends on preferred stock									0	0	0
Net income attributable to common stockholders									28	22	60
Other comprehensive income (loss), net of tax									0	2	0
Total comprehensive income									$ 28	$ 24	$ 60

Guarantor Financial Informati92

Guarantor Financial Information - Condensed Consolidating Statement of Cash Flows Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net cash provided by (used in) operating activities	$ 7,962	$ 6,135	$ 5,414
Investing activities
Purchases of property and equipment	(5,237)	(4,702)	(4,724)
Purchases of spectrum licenses and other intangible assets, including deposits	(5,828)	(3,968)	(1,935)
Purchases of short-term investments	0	0	(2,997)
Sales of short-term investments	0	2,998	0
Equity investment in subsidiary	0		0
Other, net	1	(8)	96
Net cash used in investing activities	(11,064)	(5,680)	(9,560)
Financing activities
Proceeds from capital contribution			0
Proceeds from issuance of long-term debt	10,480	997	3,979
Proceeds from tower obligations	0	0	140
Proceeds from borrowing on revolving credit facility	2,910	0	0
Repayments of revolving credit facility	(2,910)	0	0
Repayments of capital lease obligations	(486)	(205)	(57)
Repayments of short-term debt for purchases of inventory, property and equipment, net	(300)	(150)	(564)
Repayments of long-term debt	(10,230)	(20)	0
Proceeds from exercise of stock options	21	29	47
Repurchases of common shares	(427)	0	0
Intercompany advances, net	0	0	0
Equity investment from parent	0
Tax withholdings on share-based awards	(166)	(121)	(156)
Intercompany dividend paid	0	0	0
Dividends on preferred stock	(55)	(55)	(55)
Other, net	(16)	(12)	79
Net cash (used in) provided by financing activities	(1,179)	463	3,413
Change in cash and cash equivalents	(4,281)	918	(733)
Beginning of period	5,500	4,582	5,315
End of period	1,219	5,500	4,582
Consolidating and Eliminating Adjustments
Operating activities
Net cash provided by (used in) operating activities	(100)	(110)	(175)
Investing activities
Purchases of property and equipment	0	0	0
Purchases of spectrum licenses and other intangible assets, including deposits	0	0	0
Purchases of short-term investments			0
Sales of short-term investments		0
Equity investment in subsidiary	308		1,905
Other, net	0	0	0
Net cash used in investing activities	308	0	1,905
Financing activities
Proceeds from capital contribution			(1,905)
Proceeds from issuance of long-term debt	0	0	0
Proceeds from tower obligations			0
Proceeds from borrowing on revolving credit facility	0
Repayments of revolving credit facility	0
Repayments of capital lease obligations	0	0	0
Repayments of short-term debt for purchases of inventory, property and equipment, net	0	0	0
Repayments of long-term debt	0	0
Proceeds from exercise of stock options	0	0	0
Repurchases of common shares	0
Intercompany advances, net	0	0	0
Equity investment from parent	(308)
Tax withholdings on share-based awards	0	0	0
Intercompany dividend paid	100	110	175
Dividends on preferred stock	0	0	0
Other, net	0	0	0
Net cash (used in) provided by financing activities	(208)	110	(1,730)
Change in cash and cash equivalents	0	0	0
Beginning of period	0	0	0
End of period	0	0	0
Parent | Reportable Legal Entities
Operating activities
Net cash provided by (used in) operating activities	1	6	(1)
Investing activities
Purchases of property and equipment	0	0	0
Purchases of spectrum licenses and other intangible assets, including deposits	0	0	0
Purchases of short-term investments			0
Sales of short-term investments		0
Equity investment in subsidiary	(308)		(1,905)
Other, net	0	0	0
Net cash used in investing activities	(308)	0	(1,905)
Financing activities
Proceeds from capital contribution			0
Proceeds from issuance of long-term debt	0	0	0
Proceeds from tower obligations			0
Proceeds from borrowing on revolving credit facility	0
Repayments of revolving credit facility	0
Repayments of capital lease obligations	0	0	0
Repayments of short-term debt for purchases of inventory, property and equipment, net	0	0	0
Repayments of long-term debt	0	0
Proceeds from exercise of stock options	21	29	47
Repurchases of common shares	(427)
Intercompany advances, net	484	0	0
Equity investment from parent	0
Tax withholdings on share-based awards	0	0	0
Intercompany dividend paid	0	0	0
Dividends on preferred stock	(55)	(55)	(41)
Other, net	0	0	0
Net cash (used in) provided by financing activities	23	(26)	6
Change in cash and cash equivalents	(284)	(20)	(1,900)
Beginning of period	358	378	2,278
End of period	74	358	378
Issuer | Reportable Legal Entities
Operating activities
Net cash provided by (used in) operating activities	(1,613)	(1,335)	(1,147)
Investing activities
Purchases of property and equipment	0	0	0
Purchases of spectrum licenses and other intangible assets, including deposits	0	0	0
Purchases of short-term investments			(1,999)
Sales of short-term investments		2,000
Equity investment in subsidiary	0		0
Other, net	0	0	0
Net cash used in investing activities	0	2,000	(1,999)
Financing activities
Proceeds from capital contribution			1,905
Proceeds from issuance of long-term debt	10,480	997	3,979
Proceeds from tower obligations			140
Proceeds from borrowing on revolving credit facility	2,910
Repayments of revolving credit facility	0
Repayments of capital lease obligations	0	0	0
Repayments of short-term debt for purchases of inventory, property and equipment, net	0	0	0
Repayments of long-term debt	0	0
Proceeds from exercise of stock options	0	0	0
Repurchases of common shares	0
Intercompany advances, net	(14,817)	(696)	(3,357)
Equity investment from parent	308
Tax withholdings on share-based awards	0	0	0
Intercompany dividend paid	0	0	0
Dividends on preferred stock	0	0	0
Other, net	0	0	0
Net cash (used in) provided by financing activities	(1,119)	301	2,667
Change in cash and cash equivalents	(2,732)	966	(479)
Beginning of period	2,733	1,767	2,246
End of period	1	2,733	1,767
Guarantor Subsidiaries | Reportable Legal Entities
Operating activities
Net cash provided by (used in) operating activities	9,616	7,541	6,652
Investing activities
Purchases of property and equipment	(5,237)	(4,702)	(4,724)
Purchases of spectrum licenses and other intangible assets, including deposits	(5,828)	(3,968)	(1,935)
Purchases of short-term investments			(998)
Sales of short-term investments		998
Equity investment in subsidiary	0		0
Other, net	1	(8)	96
Net cash used in investing activities	(11,064)	(7,680)	(7,561)
Financing activities
Proceeds from capital contribution			0
Proceeds from issuance of long-term debt	0	0	0
Proceeds from tower obligations			0
Proceeds from borrowing on revolving credit facility	0
Repayments of revolving credit facility	(2,910)
Repayments of capital lease obligations	(486)	(205)	(57)
Repayments of short-term debt for purchases of inventory, property and equipment, net	(300)	(150)	(564)
Repayments of long-term debt	(10,230)	(20)
Proceeds from exercise of stock options	0	0	0
Repurchases of common shares	0
Intercompany advances, net	14,300	625	3,288
Equity investment from parent	0
Tax withholdings on share-based awards	(166)	(121)	(156)
Intercompany dividend paid	0	0	0
Dividends on preferred stock	0	0	(14)
Other, net	(16)	(12)	79
Net cash (used in) provided by financing activities	192	117	2,576
Change in cash and cash equivalents	(1,256)	(22)	1,667
Beginning of period	2,342	2,364	697
End of period	1,086	2,342	2,364
Non-Guarantor Subsidiaries | Reportable Legal Entities
Operating activities
Net cash provided by (used in) operating activities	58	33	85
Investing activities
Purchases of property and equipment	0	0	0
Purchases of spectrum licenses and other intangible assets, including deposits	0	0	0
Purchases of short-term investments			0
Sales of short-term investments		0
Equity investment in subsidiary	0		0
Other, net	0	0	0
Net cash used in investing activities	0	0	0
Financing activities
Proceeds from capital contribution			0
Proceeds from issuance of long-term debt	0	0	0
Proceeds from tower obligations			0
Proceeds from borrowing on revolving credit facility	0
Repayments of revolving credit facility	0
Repayments of capital lease obligations	0	0	0
Repayments of short-term debt for purchases of inventory, property and equipment, net	0	0	0
Repayments of long-term debt	0	0
Proceeds from exercise of stock options	0	0	0
Repurchases of common shares	0
Intercompany advances, net	33	71	69
Equity investment from parent	0
Tax withholdings on share-based awards	0	0	0
Intercompany dividend paid	(100)	(110)	(175)
Dividends on preferred stock	0	0	0
Other, net	0	0	0
Net cash (used in) provided by financing activities	(67)	(39)	(106)
Change in cash and cash equivalents	(9)	(6)	(21)
Beginning of period	67	73	94
End of period	$ 58	$ 67	$ 73

Quarterly Financial Informati93

Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information [Abstract]
Total revenues	$ 10,759	$ 10,019	$ 10,213	$ 9,613	$ 10,234	$ 9,305	$ 9,287	$ 8,664	$ 40,604	$ 37,490	$ 32,467
Operating income	1,112	1,323	1,416	1,037	1,001	1,048	833	1,168	4,888	4,050	2,479
Net income	2,707	550	581	698	390	366	225	479	4,536	1,460	733
Dividends on preferred stock	(14)	(13)	(14)	(14)	(14)	(13)	(14)	(14)	(55)	(55)	(55)
Net income attributable to common stockholders	$ 2,693	$ 537	$ 567	$ 684	$ 376	$ 353	$ 211	$ 465	$ 4,481	$ 1,405	$ 678
Earnings per share - basic (in USD per share)	$ 3.22	$ 0.65	$ 0.68	$ 0.83	$ 0.46	$ 0.43	$ 0.26	$ 0.57	$ 5.39	$ 1.71	$ 0.83
Earnings per share - diluted (in USD per share)	$ 3.11	$ 0.63	$ 0.67	$ 0.80	$ 0.45	$ 0.42	$ 0.25	$ 0.56	$ 5.20	$ 1.69	$ 0.82
Weighted average shares outstanding - basic (in shares)	837,416,683	831,189,779	830,971,528	827,723,034	824,982,734	822,998,697	822,434,490	819,431,761	831,850,073	822,470,275	812,994,028
Weighted average shares outstanding - diluted (in shares)	871,501,578	871,420,065	870,456,447	869,395,250	867,262,400	832,257,819	829,752,956	859,382,827	871,787,450	833,054,545	822,617,938
Cost of MetroPCS business combination					$ (6)	$ 15	$ 59	$ 36	$ 0	$ 104	$ 376
Gains on disposal of spectrum licenses	$ (168)	$ (29)	$ (1)	$ (37)	$ 0	$ (199)	$ 0	$ (636)	$ (235)	$ (835)	$ (163)