T-Mobile US (TMUS) 10-K 7 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2018	Feb. 04, 2019	Jun. 30, 2018
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, 2018
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Document Fiscal Year Focus	2,018
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		850,221,464
Entity Public Float			$ 18.3

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 1,203	$ 1,219
Accounts receivable, net of allowances of $67 and $86	1,769	1,915
Equipment installment plan receivables, net	2,538	2,290
Accounts receivable from affiliates	11	22
Inventories	1,084	1,566
Other current assets	1,676	1,903
Total current assets	8,281	8,915
Property and equipment, net	23,359	22,196
Goodwill	1,901	1,683
Spectrum licenses	35,559	35,366
Other intangible assets, net	198	217
Equipment installment plan receivables due after one year, net	1,547	1,274
Other assets	1,623	912
Total assets	72,468	70,563
Current liabilities
Accounts payable and accrued liabilities	7,741	8,528
Payables to affiliates	200	182
Short-term debt	841	1,612
Deferred revenue	698	779
Other current liabilities	787	414
Total current liabilities	10,267	11,515
Long-term debt	12,124	12,121
Long-term debt to affiliates	14,582	14,586
Tower obligations	2,557	2,590
Deferred tax liabilities	4,472	3,537
Deferred rent expense	2,781	2,720
Other long-term liabilities	967	935
Total long-term liabilities	37,483	36,489
Commitments and contingencies (Note 15)
Stockholders' equity
Common Stock, par value $0.00001 per share, 1,000,000,000 shares authorized; 851,675,119 and 860,861,998 shares issued, 850,180,317 and 859,406,651 shares outstanding	0	0
Additional paid-in capital	38,010	38,629
Treasury stock, at cost, 1,494,802 and 1,455,347 shares issued	(6)	(4)
Accumulated other comprehensive income	(332)	8
Accumulated deficit	(12,954)	(16,074)
Total stockholders' equity	24,718	22,559
Total liabilities and stockholders' equity	$ 72,468	$ 70,563

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowances	$ 67	$ 86
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)	851,675,119	860,861,998
Common stock, shares outstanding (in shares)	850,180,317	859,406,651
Treasury stock, at cost (in shares)	1,494,802	1,455,347

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues
Revenues	$ 43,310	$ 40,604	$ 37,490
Operating expenses
Selling, general and administrative	13,161	12,259	11,378
Depreciation and amortization	6,486	5,984	6,243
Cost of MetroPCS business combination	0	0	104
Gains on disposal of spectrum licenses	0	(235)	(835)
Total operating expense	38,001	35,716	33,440
Operating income	5,309	4,888	4,050
Other income (expense)
Interest expense	(835)	(1,111)	(1,418)
Interest expense to affiliates	(522)	(560)	(312)
Interest income	19	17	13
Other income (expense), net	(54)	(73)	(6)
Total other expense, net	(1,392)	(1,727)	(1,723)
Income before income taxes	3,917	3,161	2,327
Income tax (expense) benefit	(1,029)	1,375	(867)
Net income	2,888	4,536	1,460
Dividends on preferred stock	0	(55)	(55)
Net income attributable to common stockholders	2,888	4,481	1,405
Net income	2,888	4,536	1,460
Other comprehensive (loss) income, net of tax
Unrealized gain on available-for-sale securities, net of tax effect of $0, $2 and $1	0	7	2
Unrealized loss on cash flow hedges, net of tax effect of ($115), $0 and $0	(332)
Unrealized loss on cash flow hedges, net of tax effect of ($115), $0 and $0		0	0
Other comprehensive (loss) income	(332)	7	2
Total comprehensive income	$ 2,556	$ 4,543	$ 1,462
Earnings per share
Basic (in USD per share)	$ 3.40	$ 5.39	$ 1.71
Diluted (in USD per share)	$ 3.36	$ 5.20	$ 1.69
Weighted average shares outstanding
Basic (in shares)	849,744,152	831,850,073	822,470,275
Diluted (in shares)	858,290,174	871,787,450	833,054,545
Branded postpaid revenues
Revenues
Revenues	$ 20,862	$ 19,448	$ 18,138
Branded prepaid revenues
Revenues
Revenues	9,598	9,380	8,553
Wholesale revenues
Revenues
Revenues	1,183	1,102	903
Roaming and other service revenues
Revenues
Revenues	349	230	250
Service
Revenues
Revenues	31,992	30,160	27,844
Operating expenses
Cost of services and equipment sales	6,307	6,100	5,731
Equipment
Revenues
Revenues	10,009	9,375	8,727
Operating expenses
Cost of services and equipment sales	12,047	11,608	10,819
Other revenues
Revenues
Revenues	$ 1,309	$ 1,069	$ 919

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Unrealized gain on available-for-sale securities, net of tax effect of $0, $2 and $1	$ 0	$ 2	$ 1
Unrealized loss on cash flow hedges, net of tax effect of ($115), $0 and $0	$ (115)
Unrealized loss on cash flow hedges, net of tax effect of ($115), $0 and $0		$ 0	$ 0

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income	$ 2,888	$ 4,536	$ 1,460
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	6,486	5,984	6,243
Stock-based compensation expense	424	306	235
Deferred income tax expense (benefit)	980	(1,404)	914
Bad debt expense	297	388	477
Losses from sales of receivables	157	299	228
Deferred rent expense	26	76	121
Losses on redemption of debt	122	86	0
Gains on disposal of spectrum licenses	0	(235)	(835)
Changes in operating assets and liabilities
Accounts receivable	(4,617)	(3,931)	(3,459)
Equipment installment plan receivables	(1,598)	(1,812)	(673)
Inventories	(201)	(844)	(802)
Other current and long-term assets	(181)	(575)	(133)
Accounts payable and accrued liabilities	(867)	1,079	(1,201)
Other current and long-term liabilities	(69)	(233)	158
Other, net	52	111	46
Net cash provided by operating activities	3,899	3,831	2,779
Investing activities
Purchases of property and equipment, including capitalized interest of $362, $136 and $142	(5,541)	(5,237)	(4,702)
Purchases of spectrum licenses and other intangible assets, including deposits	(127)	(5,828)	(3,968)
Proceeds related to beneficial interests in securitization transactions	5,406	4,319	3,356
Acquisition of companies, net of cash acquired	(338)	0	0
Sales of short-term investments	0	0	2,998
Other, net	21	1	(8)
Net cash used in investing activities	(579)	(6,745)	(2,324)
Financing activities
Proceeds from issuance of long-term debt	2,494	10,480	997
Proceeds from borrowing on revolving credit facility	6,265	2,910	0
Repayments of revolving credit facility	(6,265)	(2,910)	0
Repayments of capital lease obligations	(700)	(486)	(205)
Repayments of short-term debt for purchases of inventory, property and equipment, net	(300)	(300)	(150)
Repayments of long-term debt	(3,349)	(10,230)	(20)
Repurchases of common stock	(1,071)	(427)	0
Tax withholdings on share-based awards	(146)	(166)	(121)
Dividends on preferred stock	0	(55)	(55)
Cash payments for debt prepayment or debt extinguishment costs	(212)	(188)	0
Other, net	(52)	5	17
Net cash (used in) provided by financing activities	(3,336)	(1,367)	463
Change in cash and cash equivalents	(16)	(4,281)	918
Cash and cash equivalents
Beginning of period	1,219	5,500	4,582
End of period	1,203	1,219	5,500
Supplemental disclosure of cash flow information
Interest payments, net of amounts capitalized, $0, $79 and $0 of which recorded as debt discount	1,525	2,028	1,681
Income tax payments	51	31	25
Noncash beneficial interest obtained in exchange for securitized receivables	4,972	4,063	3,411
Noncash investing and financing activities
Changes in accounts payable for purchases of property and equipment	65	313	285
Leased devices transferred from inventory to property and equipment	1,011	1,131	1,588
Returned leased devices transferred from property and equipment to inventory	(326)	(742)	(602)
Issuance of short-term debt for financing of property and equipment	291	292	150
Assets acquired under capital lease obligations	$ 885	$ 887	$ 799

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Cash Flows [Abstract]
Capitalized interest	$ 362	$ 136	$ 142
Discount	$ 0	$ 79	$ 0

Consolidated Statement of Stock

Consolidated Statement 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, 2015		$ 16,557			$ 0	$ 38,666	$ (1)	$ (22,108)
Preferred stock, shares outstanding, beginning (in shares) at Dec. 31, 2015			20,000,000
Common stock, shares outstanding, beginning (in shares) at Dec. 31, 2015				818,391,219
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		1,460						1,460
Other comprehensive income		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					(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
Common stock, shares outstanding, ending (in shares) at Dec. 31, 2016				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		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					(3)	3
Dividends on preferred stock		$ (55)				(55)
Preferred stock, shares outstanding, ending (in shares) at Dec. 31, 2017			0
Common stock, shares outstanding, ending (in shares) at Dec. 31, 2017		859,406,651		859,406,651.4
Balance, end of period at Dec. 31, 2017		$ 22,559			(4)	38,629	8	(16,074)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		2,888						2,888
Other comprehensive income		(332)					(332)
Stock-based compensation		473				473
Exercise of stock options (in shares)				187,965
Exercise of stock options		3				3
Stock issued for employee stock purchase plan (in shares)				2,011,794
Stock issued for employee stock purchase plan		103				103
Issuance of vested restricted stock units (in shares)				7,448,148
Issuance of restricted stock awards (in shares)				225,799
Shares withheld related to net share settlement of stock awards and stock options (in shares)				(2,321,827)
Shares withheld related to net share settlement of stock awards and stock options		$ (146)				(146)
Repurchases of common stock (in shares)		(16,738,758)		(16,738,758)
Repurchases of common stock		$ (1,054)				(1,054)
Transfer RSU to NQDC plan (in shares)				(39,455)
Transfer RSU to NQDC plan					(2)	2
Prior year Retained Earnings	[1]	$ 224					(8)	232
Preferred stock, shares outstanding, ending (in shares) at Dec. 31, 2018			0
Common stock, shares outstanding, ending (in shares) at Dec. 31, 2018		850,180,317		850,180,317
Balance, end of period at Dec. 31, 2018		$ 24,718			$ (6)	$ 38,010	$ (332)	$ (12,954)
[1]	On January 1, 2018, we adopted three ASUs which resulted in adjustments to Accumulated other comprehensive income and Accumulated deficit. The adoption of the new revenue standard resulted in an adjustment to Accumulated deficit of $213 million. The adoption of ASU 2016-01 resulted in a reclassification of Accumulated other comprehensive income to Accumulated deficit of $8 million. The adoption of ASU 2016-16 resulted in an adjustment to Accumulated deficit of $11 million. 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.

Consolidated Statement of Sto_2

Consolidated Statement of Stockholders' Equity (Parenthetical) $ in Millions	Jan. 01, 2018USD ($)
Accounting Standards Update 2014-09
Adjustment for adoption of new accounting standard	$ 213
Accounting Standards Update 2016-01 | Accumulated Deficit
Adjustment for adoption of new accounting standard	8
Accounting Standards Update 2016-16 | Accumulated Deficit
Adjustment for adoption of new accounting standard	$ 11

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
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 Metro™ by T-Mobile (“Metro by T-Mobile”), in the United States (“U.S.”), Puerto Rico and the U.S. Virgin Islands. All of our revenues were earned in, and all of our long-lived assets are located in, the 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 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 standalone 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, fair value 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 these estimates. We operate as a single operating segment. Certain prior year amounts have been reclassified to conform to the current year’s presentation. See “Accounting Pronouncements Adopted in the Current Year” below. 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 our Consolidated Balance Sheets 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 36 months using an EIP. EIP receivables not held for sale are reported in our Consolidated Balance Sheets 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 if the EIP term exceeds 12 months as there is no stated rate of interest on the EIP receivables. The EIP receivables are recorded at their present value, which is determined by discounting future cash payments at the imputed interest rate. The difference between the recorded amount of the EIP receivables and their unpaid principal balance (i.e., the contractual amount due from the customer) results in a discount which is allocated to the performance obligation of the arrangement and recorded as a reduction in transaction price in Total service revenues and 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 credit loss allowance at the time of issuance as the effects of uncertainty about future cash flows resulting from credit risk 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. Total imputed discount and allowances was approximately 8.1% of the total amount of gross accounts receivable, including EIP receivables at both December 31, 2018 and 2017. 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. All of our long-lived assets are located in the U.S., including Puerto Rico and the U.S. Virgin Islands. 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 depreciable 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. JUMP! On Demand 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 that the fair value of the two reporting units, wireless business and Layer3 TV, 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 that 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. 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. All assumptions are reviewed periodically. 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 are recognized as either assets or liabilities and are measured at fair value. We do not use derivatives for trading or speculative purposes. For derivative instruments designated as cash flow hedges, changes in fair value are reported as a component of Accumulated other comprehensive income (“AOCI”) until reclassified into Interest expense in the same period the hedged transaction affects earnings, generally over the life of the related debt. Unrealized gains on derivatives designated as cash flow hedges are recorded at fair value as assets, and unrealized losses on derivatives designated as cash flow hedges are recorded at fair value as liabilities. We have 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. Revenue Recognition (effective January 1, 2018) We primarily generate our revenue from providing wireless services to customers and selling or leasing devices and accessories. Our contracts with customers may involve multiple performance obligations, which include wireless services, wireless devices or a combination thereof, and we allocate the transaction price between each performance obligation based on its relative standalone selling price. Significant Judgments The most significant judgments affecting the amount and timing of revenue from contracts with our customers include the following items: • Revenue for service contracts that we assess are not probable of collection is not recognized until the contract is completed and cash is received. Collectibility is re-assessed when there is a significant change in facts or circumstances. Our assessment of collectibility considers whether we may limit our exposure to credit risk through our right to stop transferring additional service in the event the customer is delinquent as well as certain contract terms such as down payments that reduce our exposure to credit risk. Customer credit behavior is inherently uncertain. See “Receivables and Allowance for Credit Losses”, above, for more discussion on how we assess credit risk. • Promotional EIP bill credits offered to a customer on an equipment sale that are paid over time and are contingent on the customer maintaining a service contract may result in an extended service contract based on whether a substantive penalty is deemed to exist. Determining whether contingent EIP bill credits result in a substantive termination penalty may require significant judgment. • The identification of distinct performance obligations within our service plans may require significant judgment. • Revenue is recorded net of costs paid to another party for performance obligations where we arrange for the other party to transfer goods or services to the customer (i.e., when we are acting as an agent). For example, performance obligations relating to services provided by third-party content providers where we neither controls a right to the content provider’s service nor controls the underlying service itself are presented net because we are acting as an agent. The determination of whether we control the underlying service or right to the service prior to our transfer to the customer requires, at times, significant judgment. • For transactions where we recognize a significant financing component, judgment is required to determine the discount rate. For EIP sales, the discount rate used to adjust the transaction price primarily reflects current market interest rates and the estimated credit risk of the customer. Customer credit behavior is inherently uncertain. See “Receivables and Allowance for Credit Losses”, above, for more discussion on how we assess credit risk. • Our products are generally sold with a right of return, which is accounted for as variable consideration when estimating the amount of revenue to recognize. Device return levels are estimated based on the expected value method as there are a large number of contracts with similar characteristics and the outcome of each contract is independent of the others. Historical return rate experience is a significant input to our expected value methodology. • Sales of equipment to indirect dealers who have been identified as our customer (referred to as the sell-in model) often include credits subsequently paid to the dealer as a reimbursement for any discount promotions offered to the end consumer. These credits (payments to a customer) are accounted for as variable consideration when estimating the amount of revenue to recognize from the sales of equipment to indirect dealers and are estimated based on historical experience and other factors, such as expected promotional activity. • The determination of the standalone selling price for contracts that involve more than one performance obligation may require significant judgment, such as when the selling price of a good or service is not readily observable. • For capitalized contract costs, determining the amortization period over which such costs are recognized as well as assessing the indicators of impairment may require significant judgment. Wireless Services Revenue We generate our wireless services 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 contracts are billed monthly either in advance or arrears, or are prepaid. Generally, service revenue is recognized as we satisfy our performance obligation to transfer service to our customers. We typically satisfy our stand-ready performance obligations, including unlimited wireless services, evenly over the contract term. For usage-based and prepaid wireless services, we satisfy our performance obligations when services are rendered. Revenue for service contracts that we assess are not probable of collection is not recognized until the contract is completed and cash is received. Collectibility is re-assessed when there is a significant change in facts or circumstances. Our assessment of collectibility considers whether we may limit our exposure to credit risk through our right to stop transferring additional service in the event the customer is delinquent. Consideration payable to a customer is treated as a reduction of the total transaction price, unless the payment is in exchange for a distinct good or service, such as certain commissions paid to dealers. Revenue is recorded net of costs paid to another party for performance obligations where we arrange for the other party to transfer goods or services to the customer (i.e., when we are acting as an agent). For example, performance obligations relating to services provided by third-party content providers where we neither controls a right to the content provider’s service nor controls the underlying service itself are presented net because we are acting as an agent. Federal Universal Service Fund (“USF”) and other regulatory fees are assessed by various governmental authorities in connection with the services we provide to our customers and are included in Cost of services. When we separately bill and collect these regulatory fees from customers, they are recorded gross in Total service revenues in our Consolidated Statements of Comprehensive Income . For the years ended December 31, 2018, 2017 and 2016, we recorded approximately $161 million , $258 million and $409 million , respectively, of USF fees on a gross basis. We have made an accounting policy election to exclude from the measurement of the transaction price all taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction and collected by us from a customer (for example, sales, use, value added, and some excise taxes). Equipment Revenues We generate equipment revenues from the sale or lease of mobile communication devices and accessories. For performance obligations related to equipment contracts, we typically transfer control at a point in time when the device or accessory is delivered to, and accepted by, the customer or dealer. We have elected to account for shipping and handling activities that occur after control of the related good transfers as fulfillment activities instead of assessing such activities as performance obligations. We estimate variable consideration (e.g., device returns or certain payments to indirect dealers) primarily based on historical experience. Equipment sales not probable of collection are generally recorded as payments are received. Our assessment of collectibility considers contract terms such as down payments that reduce our exposure to credit risk. We offer certain customers the option to pay for devices and accessories in installments using an EIP. Generally, we recognize as a reduction of the total transaction price the effects of a financing component in contracts where customers purchase their devices and accessories on an EIP with a term of more than one year, including those financing components that are not considered to be significant to the contract. However, we have elected the practical expedient to not recognize the effects of a significant financing component for contracts where we expect, at contract inception, that the period between the transfer of a performance obligation to a customer and the customer’s payment for that performance obligation will be one year or less. In addition, for customers who enroll in our JUMP! program, we recognize a liability based on the estimated fair value of the specified-price trade-in right guarantee. The fair value of the guarantee is deducted from the transaction price and the remaining transaction price is allocated to other elements of the contract, including service and equipment performance obligations. See “Guarantee Liabilities” above for further information. JUMP! On Demand 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 wireless devices are accounted for as operating leases and estimated contract consideration is allocated between lease elements and non-lease elements (such as service and equipment performance obligations) based on the relative standalone selling price of each performance obligation in the contract. Lease revenues are recorded as equipment revenues and recognized as earned on a straight-line basis over the lease term. Lease revenues on contracts not probable of collection are limited to the amount of payments received. See “Property and Equipment” above for further information. Contract Balances Generally, our devices and service plans are available at standard prices, which are maintained on price lists and published on our website and/or within our retail stores. For contracts that involve more than one product or service that are identified as separate performance obligations, the transaction price is allocated to the performance obligations based on their relative standalone selling prices. The

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Business Combinations	Note 2 – Business Combinations Proposed Sprint Transactions On April 29, 2018, we entered into a Business Combination Agreement to merge with Sprint in an all-stock transaction at a fixed exchange ratio of 0.10256 shares of T-Mobile common stock for each share of Sprint common stock, or 9.75 shares of Sprint common stock for each share of T-Mobile common stock (the “Merger”). The combined company will be named “T-Mobile” and, as a result of the Merger, is expected to be able to rapidly launch a nationwide 5G network, accelerate innovation and increase competition in the U.S. wireless, video and broadband industries. Neither T-Mobile nor Sprint on its own could generate comparable benefits to consumers. The Transactions have been approved by the boards of directors of T-Mobile and Sprint and the required approvals of each of T-Mobile and Sprint have been obtained. Immediately following the Merger, it is anticipated that Deutsche Telekom (“DT”) and SoftBank Group Corp. will hold, directly or indirectly, on a fully diluted basis, approximately 41.7% and 27.4% , respectively, of the outstanding T-Mobile common stock, with the remaining approximately 30.9% of the outstanding T-Mobile common stock held by other stockholders, based on closing share prices and certain other assumptions as of December 31, 2018. In connection with the entry into the Business Combination Agreement, T-Mobile USA, Inc. (“T-Mobile USA”) entered into a commitment letter, dated as of April 29, 2018 (as amended and restated on May 15, 2018, the “Commitment Letter”). The funding of the debt facilities provided for in the Commitment Letter is subject to the satisfaction of the conditions set forth therein, including consummation of the Merger. The proceeds of the debt financing provided for in the Commitment Letter will be used to refinance certain existing debt of us, Sprint and our and Sprint’s respective subsidiaries and for post-closing working capital needs of the combined company. See Note 8 – Debt for further information. In connection with the entry into the Business Combination Agreement, DT and T-Mobile USA entered into a financing matters agreement, dated as of April 29, 2018 (the “Financing Matters Agreement”). See Note 8 – Debt for further information. On May 18, 2018, under the terms and conditions described in the Consent Solicitation Statement dated as of May 14, 2018, (the “Consent Solicitation Statement”) we obtained consents necessary to effect certain amendments to certain existing debt of us and our subsidiaries. In connection with receiving the requisite consents, we made upfront payments to third-party note holders of approximately $31 million during 2018. These payments were recognized as a reduction to Long-term debt . We paid third-party bank fees associated with obtaining the requisite consents of $6 million during 2018, which we recognized as Selling, general and administrative expenses in our Consolidated Statements of Comprehensive Income . Under the terms of the Business Combination Agreement, Sprint may be required to reimburse us for 33% of the upfront consent and related bank fees we paid, or $14 million , if the Business Combination Agreement is terminated. There was no reimbursement accrued as of December 31, 2018 . On May 18, 2018, Sprint also obtained consents necessary to effect certain amendments to certain existing debt of it and its subsidiaries. In connection with receiving the requisite consents, Sprint made upfront payments to third-party note holders and related bank fees of $241 million during 2018. Under the terms of the Business Combination Agreement, we may also be required to reimburse Sprint for 67% of the upfront consent and related bank fees it paid, or $161 million , if the Business Combination Agreement is terminated. There was no fee accrued as of December 31, 2018 . For the year ended December 31, 2018 , we recognized costs associated with the Transactions of $196 million . These costs generally included bank fees associated with obtaining the requisite consents on debt to third parties, consulting and legal fees and were recognized as Selling, general and administrative expenses in our Consolidated Statements of Comprehensive Income . The consummation of the Transactions is subject to regulatory approvals and certain other customary closing conditions. We expect to receive regulatory approval in the first half of 2019. The Business Combination Agreement contains certain termination rights for both Sprint and us. If we terminate the Business Combination Agreement in connection with a failure to satisfy the closing condition related to specified minimum credit ratings for the combined company on the closing date of the Merger (after giving effect to the Merger) from at least two of the three credit rating agencies, then in certain circumstances, we may be required to pay Sprint an amount equal to $600 million . On June 18, 2018, we filed the Public Interest Statement and applications for approval of our Merger with Sprint with the FCC. On July 18, 2018, the FCC issued a Public Notice formally accepting our applications and establishing a period for public comment. The FCC is reviewing the modeling provided by us and Sprint under its informal 180-day transaction shot clock. On July 30, 2018, we filed a registration statement on Form S-4 with the SEC related to the Merger. The registration statement became effective on October 29, 2018. Acquisition of Layer3 TV On January 22, 2018, we completed our acquisition of television innovator Layer3 TV, Inc. (“Layer3 TV”) for cash consideration of $318 million . The consideration included a $5 million payment that was made after the closing date in the second quarter of 2018. Upon closing of the transaction, Layer3 TV became a wholly-owned consolidated subsidiary. Layer3 TV acquires and distributes digital entertainment programming primarily through the internet to residential customers, offering direct to home digital television and multi-channel video programming distribution services. This transaction represented an opportunity to acquire a complementary service to our existing wireless service to advance our video strategy. We accounted for the purchase of Layer3 TV as a business combination. Costs related to this acquisition were immaterial to our Consolidated Statements of Comprehensive Income . The grant-date fair value of cash-based and share-based incentive compensation awards attributable to post-combination services was approximately $37 million . The following table shows the amounts recognized as of the acquisition date for each major class of assets acquired and liabilities assumed and the resultant purchase price allocation: (in millions) January 22, Assets acquired Cash and cash equivalents $ 2 Other current assets 14 Property and equipment, net 11 Intangible assets 100 Goodwill 218 Deferred tax assets 2 Total assets acquired $ 347 Liabilities assumed Accounts payable and accrued liabilities $ 27 Short-term debt 2 Total liabilities assumed 29 Total consideration transferred $ 318 We recognized a liability of $21 million within Accounts payable and accrued liabilities in our Consolidated Balance Sheets and an associated indemnification asset of $12 million in our Consolidated Balance Sheets related to minimum commitments under acquired content agreements. As of December 31, 2018 , the $12 million had been received. Goodwill of $218 million is calculated as the excess of the purchase price paid over the net assets acquired. The goodwill recorded as part of the Layer3 TV acquisition primarily reflects industry knowledge of the retained management team, as well as intangible assets that do not qualify for separate recognition. None of the goodwill is deductible for tax purposes. See Note 6 – Goodwill, Spectrum Licenses and Other Intangible Assets for further information. As part of the transaction, we acquired an identifiable intangible asset of developed technology with an estimated fair value of $100 million , which is being amortized on a straight-line basis over a useful life of 5 years . The financial results from the acquisition of Layer3 TV since the closing date through December 31, 2018 were not material to our Consolidated Statements of Comprehensive Income . Acquisition of Iowa Wireless On January 1, 2018 (the “IWS Acquisition Date”), we closed on our previously announced Unit Purchase Agreement to acquire the remaining equity in Iowa Wireless Services, LLC (“IWS”), a 54% owned unconsolidated subsidiary, for a purchase price of $25 million . We accounted for our acquisition of IWS as a business combination. Prior to the IWS Acquisition Date, we accounted for our previously-held investment in IWS under the equity method as we had significant influence, but not control. Authoritative guidance on accounting for business combinations requires that an acquirer re-measure its previously held equity interest in the acquiree at its acquisition date fair value and recognize the resulting gain or loss in earnings. As such, we valued our previously held equity interest in IWS at $56 million as of the IWS Acquisition Date and recognized a gain of $15 million . The following table highlights the consideration transferred, the fair value of our previously held equity interest and bargain purchase: (in millions) January 1, Consideration transferred: Cash paid $ 25 Previously held equity interest: Acquisition date fair value of previously held equity interest 56 Bargain purchase gain 25 Net assets acquired $ 106 As part of the acquisition of IWS, we recognized a bargain purchase gain of approximately $25 million , which represents the fair value of the identifiable net assets acquired, primarily IWS spectrum licenses, in excess of the purchase price and fair value of our previously held equity interest. We were in a favorable position to acquire the remaining shares of IWS as a result of our previously held 54% equity interest in IWS, an unprofitable business with valuable spectrum holdings. The following table shows the amounts recognized as of the IWS Acquisition Date for each major class of assets acquired and liabilities assumed and the resultant purchase price allocation: (in millions) January 1, Assets acquired Current assets Cash and cash equivalents $ 3 Accounts receivable, net 6 Equipment installment plan receivables, net 3 Inventories 1 Other current assets 2 Current assets, total 15 Property and equipment, net 36 Spectrum licenses 87 Total assets acquired $ 138 Liabilities assumed Accounts payable and accrued liabilities $ 6 Deferred revenue 2 Current liabilities, total 8 Deferred tax liabilities 17 Other long-term liabilities 7 Total long-term liabilities 24 Net assets acquired $ 106 We included both the gain on our previously held equity interest in IWS and the bargain purchase gain within Other income (expense), net for the year ended December 31, 2018 . Pro Forma Information The acquisitions of Layer3 TV and IWS were not material to our prior period consolidated results on a pro forma basis.

Receivables and Allowance for C

Receivables and Allowance for Credit Losses	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Receivables and Allowance for Credit Losses	Note 3 – 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 receivables 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. 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 using several factors, such as credit bureau information, consumer credit risk scores and service and device 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 $ 4,534 $ 3,960 Unamortized imputed discount (330 ) (264 ) EIP receivables, net of unamortized imputed discount 4,204 3,696 Allowance for credit losses (119 ) (132 ) EIP receivables, net $ 4,085 $ 3,564 Classified on the balance sheet as: Equipment installment plan receivables, net $ 2,538 $ 2,290 Equipment installment plan receivables due after one year, net 1,547 1,274 EIP receivables, net $ 4,085 $ 3,564 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 10.0% , 9.6% and 9.0% as of December 31, 2018 , 2017 and 2016 , respectively. Activity for the years ended December 31, 2018 , 2017 and 2016 in the allowance for credit losses and unamortized imputed discount balances for the accounts receivable and EIP receivables segments were as follows: December 31, 2018 December 31, 2017 December 31, 2016 (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 $ 86 $ 396 $ 482 $ 102 $ 316 $ 418 $ 116 $ 333 $ 449 Bad debt expense 69 228 297 104 284 388 227 250 477 Write-offs, net of recoveries (88 ) (240 ) (328 ) (120 ) (273 ) (393 ) (241 ) (277 ) (518 ) Change in imputed discount on short-term and long-term EIP receivables N/A 250 250 N/A 252 252 N/A 186 186 Impact on the imputed discount from sales of EIP receivables N/A (185 ) (185 ) N/A (183 ) (183 ) N/A (176 ) (176 ) Allowance for credit losses and imputed discount, end of period $ 67 $ 449 $ 516 $ 86 $ 396 $ 482 $ 102 $ 316 $ 418 Management considers the aging of receivables to be an important credit indicator. The following table provides delinquency status for the unpaid principal balance for receivables within the EIP portfolio segment, which we actively monitor as part of our current credit risk management practices and policies: December 31, 2018 December 31, 2017 (in millions) Prime Subprime Total EIP Receivables, gross Prime Subprime Total EIP Receivables, gross Current - 30 days past due $ 1,987 $ 2,446 $ 4,433 $ 1,727 $ 2,133 $ 3,860 31 - 60 days past due 15 32 47 17 29 46 61 - 90 days past due 6 19 25 6 16 22 More than 90 days past due 7 22 29 8 24 32 Total receivables, gross $ 2,015 $ 2,519 $ 4,534 $ 1,758 $ 2,202 $ 3,960

Sales of Certain Receivables

Sales of Certain Receivables	12 Months Ended
	Dec. 31, 2018
Transfers and Servicing [Abstract]
Sales of Certain Receivables	Note 4 – Sales of Certain Receivables We have entered into transactions to sell certain service and EIP 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 Accounts Receivable Overview of the Transaction In 2014, we entered into an arrangement to sell certain service accounts receivable 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 amended and restated to extend the scheduled expiration date to March 2019. In November 2018, the service receivable sale arrangement was again amended to extend the maturity of certain third-party credit support under the arrangement until March 2019. As of December 31, 2018 and 2017, the service receivable sale arrangement provided funding of $774 million and $880 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 receivable (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 service receivable sale 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 $ 339 $ 236 Accounts payable and accrued liabilities 59 25 Other current liabilities 149 180 Sales of EIP Receivables Overview of the Transaction In 2015, we entered into an arrangement to sell certain EIP accounts receivable on a revolving basis. 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 . In October 2018, we amended and restated the EIP sale arrangement to, among other things, extend the scheduled expiration date to November 2020 and expand the types of EIP receivables that may be sold. In December 2018, we amended the EIP sale arrangement to increase the term of EIP accounts receivables relating to handset devices that may be sold in the EIP sale arrangement to expand the eligibility criteria for longer tenor EIP loans. As of both December 31, 2018 and 2017 , the EIP sale arrangement provided funding of $1.3 billion . Sales of EIP receivables occur daily and are settled on a monthly basis. 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 third-party 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 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 $ 321 $ 403 Other assets 88 109 Other long-term liabilities 22 3 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 cash proceeds received upon sale in Net cash provided by operating activities in our Consolidated Statements of Cash Flows . We recognize proceeds 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 used in investing activities in our Consolidated Statements of Cash Flows as Proceeds related to beneficial interests in securitization transactions . 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, 2018 and 2017 , our deferred purchase price related to the sales of service receivables and EIP receivables was $746 million and $745 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 $ 2,577 $ 2,725 Other current assets 660 639 of which, deferred purchase price 658 636 Other long-term assets 88 109 of which, deferred purchase price 88 109 Accounts payable and accrued liabilities 59 25 Other current liabilities 149 180 Other long-term liabilities 22 3 Net cash proceeds since inception 1,879 2,058 Of which: Change in net cash proceeds during the year-to-date period (179 ) 28 Net cash proceeds funded by reinvested collections 2,058 2,030 We recognized losses from sales of receivables, including adjustments to the receivables’ fair values and changes in fair value of the deferred purchase price, of $157 million , $299 million and $228 million for the years ended December 31, 2018 , 2017 and 2016 , respectively, in Selling, general and administrative expense in our Consolidated Statements of Comprehensive Income . 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 $1.2 billion as of December 31, 2018 . 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, 2018
Property, Plant and Equipment [Abstract]
Property and Equipment	Note 5 – 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 $ 2,423 $ 2,066 Wireless communications systems Up to 20 years 35,282 32,706 Leasehold improvements Up to 12 years 1,299 1,182 Capitalized software Up to 10 years 11,712 10,563 Leased devices Up to 18 months 1,164 1,209 Construction in progress 2,776 1,771 Accumulated depreciation and amortization (31,297 ) (27,301 ) Property and equipment, net $ 23,359 $ 22,196 Wireless communication systems include capital lease agreements for network equipment with varying expiration terms through 2033 . Capital lease assets and accumulated amortization were $3.1 billion and $867 million , and $2.4 billion and $533 million , as of December 31, 2018 and 2017 , respectively. We capitalize interest associated with the acquisition or construction of certain property and equipment and spectrum intangible assets. We recognized capitalized interest of $362 million , $136 million and $142 million for the years ended December 31, 2018 , 2017 and 2016 , 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 $ 1,159 $ 1,209 Accumulated depreciation (622 ) (417 ) Leased wireless devices, net $ 537 $ 792 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, 2019 $ 419 2020 59 Total $ 478 Total depreciation expense relating to property and equipment was $6.4 billion , $5.8 billion and $6.0 billion for the years ended December 31, 2018 , 2017 and 2016 , respectively. Included in the total depreciation expense for the years ended December 31, 2018 , 2017 and 2016 was $940 million , $1.0 billion and $1.5 billion , respectively, related to leased wireless devices. For the years ended December 31, 2018 , 2017 and 2016 , we recorded additional depreciation expense of $60 million , $63 million and $101 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 $ 562 $ 539 Liabilities incurred 26 25 Liabilities settled (9 ) (16 ) Accretion expense 30 27 Changes in estimated cash flows — (13 ) Asset retirement obligations, end of year $ 609 $ 562 Classified on the balance sheet as: Other current liabilities $ — $ 3 Other long-term liabilities 609 559 Asset retirement obligations $ 609 $ 562 The corresponding assets, net of accumulated depreciation, related to asset retirement obligations were $194 million and $220 million as of December 31, 2018 and 2017 , respectively.

Goodwill, Spectrum License Tran

Goodwill, Spectrum License Transactions and Other Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Spectrum License Transactions and Other Intangible Assets	Note 6 – Goodwill, Spectrum License Transactions and Other Intangible Assets Goodwill The changes in the carrying amount of goodwill for the years ended December 31, 2018 and 2017 are as follows: (in millions) Goodwill Historical goodwill $ 12,449 Accumulated impairment losses at December 31, 2017 (10,766 ) Balance as of December 31, 2017 1,683 Goodwill from acquisition of Layer3 TV 218 Balance as of December 31, 2018 $ 1,901 Accumulated impairment losses at December 31, 2018 $ (10,766 ) On January 22, 2018, we completed our acquisition of Layer3 TV. This purchase was accounted for as a business combination resulting in $218 million in goodwill. Layer3 TV is a separate reporting unit and the acquired goodwill is tested for impairment at this level. See Note 2 – Business Combinations for further information. Spectrum Licenses The following table summarizes our spectrum license activity for the years ended December 31, 2018 and 2017 : (in millions) 2018 2017 Spectrum licenses, beginning of year $ 35,366 $ 27,014 Spectrum license acquisitions 138 8,599 Spectrum licenses transferred to held for sale (1 ) (271 ) Costs to clear spectrum 56 24 Spectrum licenses, end of year $ 35,559 $ 35,366 We had the following spectrum license transactions during 2018 : • We recorded spectrum licenses received as part of our acquisition of the remaining equity interest in IWS at their estimated fair value of approximately $87 million . See Note 2 – Business Combinations for further information. • We closed on multiple spectrum purchase agreements in which we acquired total spectrum licenses of approximately $50 million for cash consideration. • In September 2018, we signed a reciprocal long-term lease agreement with Sprint in which both parties have the right to use a portion of spectrum owned by the other party. This executory agreement does not qualify as an acquisition of spectrum licenses, and we have not capitalized amounts related to the lease. The reciprocal long-term lease is a distinct transaction from the Merger. See Note 15 – Commitments and Contingencies for further information. 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. 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 . Goodwill and Other Intangible Assets Impairment Assessments Our impairment assessment of goodwill and other indefinite-lived intangible assets (spectrum licenses) resulted in no impairment as of December 31, 2018 and 2017 . Other Intangible Assets The components of Other intangible assets were as follows: Useful Lives December 31, 2018 December 31, 2017 (in millions) Gross Amount Accumulated Amortization Net Amount Gross Amount Accumulated Amortization Net Amount Customer lists Up to 6 years $ 1,104 $ (1,086 ) $ 18 $ 1,104 $ (1,016 ) $ 88 Trademarks and patents Up to 19 years 312 (225 ) 87 307 (192 ) 115 Other Up to 28 years 149 (56 ) 93 49 (35 ) 14 Other intangible assets $ 1,565 $ (1,367 ) $ 198 $ 1,460 $ (1,243 ) $ 217 Amortization expense for intangible assets subject to amortization was $124 million , $163 million and $220 million for the years ended December 31, 2018 , 2017 and 2016 , 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, 2019 $ 73 2020 55 2021 35 2022 25 2023 6 Thereafter 4 Total $ 198

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 7 – Fair Value Measurements The carrying values of Cash and cash equivalents , Accounts receivable, Accounts receivable from affiliates , Accounts payable and accrued liabilities , and borrowings under our revolving credit facility with DT, our majority stockholder, approximate fair value due to the short-term maturities of these instruments. Derivative Financial Instruments Interest rate lock derivatives On October 1, 2018, we adopted the new derivatives and hedging standard and have applied the standard to hedging transactions prospectively. See Note 1 – Summary of Significant Accounting Policies for further discussion on the adoption of this standard. Periodically, we use derivatives to manage exposure to market risk, such as interest rate risk. We designate certain derivatives as hedging instruments in a qualifying hedge accounting relationship (cash flow hedge) to help minimize significant, unplanned fluctuations in cash flows caused by interest rate volatility. We do not use derivatives for trading or speculative purposes. We enter into and designate interest rate lock derivatives (forward-starting swap instruments) as cash flow hedges to reduce variability in cash flows due to changes in interest payments attributable to increases or decreases in the benchmark interest rate during the period leading up to the probable issuance of fixed-rate debt. We record interest rate lock derivatives on our Consolidated Balance Sheets at fair value that is derived primarily from observable market data, including yield curves. Interest rate lock derivatives were classified as Level 2 in the fair value hierarchy. Cash flows associated with derivative instruments are presented in the same category on the Consolidated Statements of Cash Flows as the item being hedged. In October 2018, we entered into interest rate lock derivatives with notional amounts of $9.6 billion . The fair value of interest rate lock derivatives as of December 31, 2018 was $447 million and is included in Other current liabilities in our Consolidated Balance Sheets . As of and for the year ended December 31, 2018 , no amounts were accrued or amortized into Interest expense in the Consolidated Statements of Comprehensive Income while changes in fair value, net of tax, of $332 million are presented in AOCI. Embedded derivatives In connection with our business combination with MetroPCS, we issued senior reset notes to DT. 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. The interest rates on our senior reset notes to DT 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. Our embedded derivatives are recorded at fair value primarily based on unobservable inputs and were classified as Level 3 in the fair value hierarchy for 2018 and 2017. The fair value of embedded derivative instruments was $19 million and $66 million as of December 31, 2018 and 2017, respectively, and is included in Other long-term liabilities in our Consolidated Balance Sheets . For the years ended December 31, 2018 , 2017 and 2016, we recognized $29 million , $52 million and $25 million from the gain activity related to embedded derivatives instruments in Interest expense to affiliates in our Consolidated Statements of Comprehensive Income . Deferred Purchase Price Assets In connection with the sales of certain service and EIP accounts receivable 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 4 – Sales of Certain Receivables for further information . The carrying amounts and fair values of our assets 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, 2018 December 31, 2017 (in millions) Carrying Amount Fair Value Carrying Amount Fair Value Assets: Deferred purchase price assets 3 $ 746 $ 746 $ 745 $ 745 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 our Senior Notes to affiliates , Incremental Term Loan Facility to affiliates and Senior Reset Notes to affiliates were determined based on a discounted cash flow approach using market interest rates 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 and Senior Reset Notes to affiliates 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 and Senior Reset Notes to affiliates . The fair value estimates were based on information available as of December 31, 2018 and 2017 . As such, our estimates are not necessarily indicative of the amount we could realize in a current market exchange. The carrying 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, 2018 December 31, 2017 (in millions) Carrying Amount Fair Value Carrying Amount Fair Value Liabilities: Senior Notes to third parties 1 $ 10,950 $ 10,945 $ 11,910 $ 12,540 Senior Notes to affiliates 2 9,984 9,802 7,486 7,852 Incremental Term Loan Facility to affiliates 2 4,000 3,976 4,000 4,020 Senior Reset Notes to affiliates 2 598 640 3,100 3,260 Guarantee Liabilities We offer a device trade-in program, JUMP!, which provides eligible customers a specified-price trade-in right to upgrade their device. 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, incorporating the expected probability and timing of handset upgrade and the estimated fair value of the 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 EIP balance 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 carrying amounts of our guarantee liabilities measured at fair value on a non-recurring basis included in our Consolidated Balance Sheets were $73 million and $105 million as of December 31, 2018 and 2017 , respectively. 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 $3.0 billion as of December 31, 2018 . 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, 2018
Debt Disclosure [Abstract]
Debt	Note 8 – Debt Debt was as follows: (in millions) December 31, December 31, 8.097% Senior Reset Notes to affiliates due 2021 $ — $ 1,250 5.300% Senior Notes to affiliates due 2021 2,000 2,000 8.195% Senior Reset Notes to affiliates due 2022 — 1,250 4.000% Senior Notes to affiliates due 2022 1,000 1,000 4.000% Senior Notes due 2022 500 500 6.125% Senior Notes due 2022 — 1,000 Incremental term loan facility to affiliates due 2022 2,000 2,000 6.000% Senior Notes due 2023 1,300 1,300 6.625% Senior Notes due 2023 — 1,750 6.836% Senior Notes due 2023 — 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 1,350 6.000% Senior Notes to affiliates due 2024 650 650 Incremental term loan facility to affiliates due 2024 2,000 2,000 5.125% Senior Notes to affiliates due 2025 1,250 1,250 5.125% Senior Notes due 2025 500 500 6.375% Senior Notes due 2025 1,700 1,700 6.500% Senior Notes due 2026 2,000 2,000 4.500% Senior Notes due 2026 1,000 — 4.500% Senior Notes to affiliates due 2026 1,000 — 5.375% Senior Notes due 2027 500 500 5.375% Senior Notes to affiliates due 2027 1,250 1,250 4.750% Senior Notes due 2028 1,500 — 4.750% Senior Notes to affiliates due 2028 1,500 — Capital leases 2,015 1,824 Unamortized premium from purchase price allocation fair value adjustment — 78 Unamortized premium on debt to affiliates 52 59 Unamortized discount on Senior Notes to affiliates (64 ) (73 ) Debt issuance costs and consent fees (56 ) (19 ) Total debt 27,547 28,319 Less: Current portion of Senior Notes — 999 Less: Current portion of capital leases 841 613 Total long-term debt $ 26,706 $ 26,707 Classified on the balance sheet as: Long-term debt $ 12,124 $ 12,121 Long-term debt to affiliates 14,582 14,586 Total long-term debt $ 26,706 $ 26,707 Debt to Third Parties During the year ended December 31, 2018 we issued the following Senior Notes: (in millions) Principal Issuances Issuance Costs Net Proceeds from Issuance of Long-Term Debt Issue Date 4.500% Senior Notes due 2026 $ 1,000 $ 2 $ 998 January 25, 2018 4.750% Senior Notes due 2028 1,500 4 1,496 January 25, 2018 Total of Senior Notes issued $ 2,500 $ 6 $ 2,494 We used the net proceeds of $2.494 billion from the public debt issuance to redeem our $1.750 billion of 6.625% Senior Notes due 2023 on April 1, 2018, and to redeem our $600 million of 6.836% Senior Notes due 2023 on April 28, 2018, and for general corporate purposes, including the partial repayment of borrowings under our revolving credit facility with DT. During the year ended December 31, 2018 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 6.125% Senior Notes due 2022 $ 1,000 $ 1 $ 31 January 15, 2018 103.063 % 6.625% Senior Notes due 2023 1,750 (75 ) 58 April 1, 2018 103.313 % 6.836% Senior Notes due 2023 600 — 21 April 28, 2018 103.418 % (1) Write-off of premiums, discounts, issuance costs and call penalties are included in Other income (expense), net in our Consolidated Statements of Comprehensive Income . Write-off of premiums, discounts and issuance costs are included in Losses on redemption of debt 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 (used in) provided by financing activities in our Consolidated Statements of Cash Flows . Debt to Affiliates On April 30, 2018, DT purchased (i) $1.0 billion in aggregate principal amount of 4.500% Senior Notes due 2026 and (ii) $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 “New DT Notes”). We used the net proceeds of $2.5 billion from the transaction to refinance existing indebtedness to DT as follows: (in millions) Principal Amount Write -off of Embedded Derivatives (1) Other (2) Redemption Redemption Price 8.097% Senior Notes due 2021 $ 1,250 $ (8 ) $ 51 April 28, 2018 104.0485 % 8.195% Senior Notes due 2022 1,250 (8 ) 51 April 28, 2018 104.0975 % Total $ 2,500 $ (16 ) $ 102 (1) Certain components of the reset features were required to be bifurcated from the DT Senior Reset Notes and separately accounted for as embedded derivative instruments. Write-off of embedded derivatives are included in Losses on redemption of debt within Net cash provided by operating activities in our Consolidated Statements of Cash Flows . (2) Cash for 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. Incremental Term Loan Facility In March 2018, we amended the terms of our secured term loan facility (“Incremental Term Loan Facility”) with DT, our majority stockholder. Following this amendment, the applicable margin payable on LIBOR indexed loans is 1.50% under the $2.0 billion Incremental Term Loan Facility maturing on November 9, 2022 and 1.75% under the $2.0 billion Incremental Term Loan Facility maturing on January 31, 2024. The amendment also modified the Incremental Term Loan Facility to (i) include a soft-call prepayment premium of 1.00% of the outstanding principal amount of the loans under the Incremental Term Loan Facility payable to DT upon certain refinancings of such loans by us with lower priced debt prior to a date that is six months after March 29, 2018 and (ii) update certain covenants and other provisions to make them substantially consistent, subject to certain additional carve outs, with our most recently issued public notes. No issuance fees were incurred related to this debt facility for the years ended December 31, 2018 or 2017 . Commitment Letter Under the Commitment Letter in connection with the Merger, certain financial institutions named therein have committed to provide up to $30.0 billion in secured and unsecured debt financing, including a $4.0 billion secured revolving credit facility, a $7.0 billion secured term loan facility and a $19.0 billion secured bridge loan facility. In connection with the financing provided for in the Commitment Letter, we expect to incur certain fees if the Merger closes, including fees for the financial institutions structuring and providing the commitments for the secured term loan facility, secured revolving loan facility and the secured bridge loan, and certain take-out fees associated with the issuance of permanent secured bond debt in lieu of the secured bridge loan. We expect to incur up to approximately $340 million if the closing date occurs on or after April 29, 2019. There was no fee accrued as of December 31, 2018 . We also may be required to draw down on the $7.0 billion secured term loan facility on May 1, 2019, and would be required to place the proceeds in escrow and pay interest thereon until the Merger closes. Financing Matters Agreement Pursuant to the Financing Matters Agreement, DT agreed, among other things, to consent to the incurrence by T-Mobile USA of secured debt in connection with and after the consummation of the Merger, and to provide a lock up on sales thereby as to certain senior notes of T-Mobile USA held thereby. In addition, T-Mobile USA agreed, among other things, to repay and terminate, upon closing of the Merger, the Incremental Term Loan Facility and the revolving credit facility of T-Mobile USA which are provided by DT, as well as $2.0 billion of T-Mobile USA’s 5.300% Senior Notes due 2021 and $2.0 billion of T-Mobile USA’s 6.000% Senior Notes due 2024. In addition, T-Mobile USA and DT agreed, upon closing of the Merger, to amend the $1.25 billion of T-Mobile USA’s 5.125% Senior Notes due 2025 and $1.25 billion of T-Mobile USA’s 5.375% Senior Notes due 2027 to change the maturity dates thereof to April 15, 2021 and April 15, 2022, respectively (the “2025 and 2027 Amendments”). In connection with receiving the requisite consents, we made upfront payments to DT of $7 million during the second quarter of 2018. These payments were recognized as a reduction to Long-term debt to affiliates in our Consolidated Balance Sheets. In accordance with the consents received from DT, on December 20, 2018, T-Mobile USA, the guarantors and Deutsche Bank Trust Company Americas, as trustee, executed and delivered the 38 th supplemental indenture to the Indenture, pursuant to which, with respect to certain T-Mobile USA Senior Notes held by DT, the Proposed Amendments (as defined below under “Consents on Debt to Third Parties”) and the 2025 and 2027 Amendments will become effective immediately prior to the consummation of the Merger. If the Merger is consummated, we will make additional payments for requisite consents to DT of $20 million . There was no additional payment accrued as of December 31, 2018 . Consents on Debt to Third Parties On May 18, 2018, under the terms and conditions described in the Consent Solicitation Statement, we obtained consents necessary to effect certain amendments to our Senior Notes to third parties in connection with the Business Combination Agreement. Pursuant to the Consent Solicitation Statement, third-party note holders agreed, among other things, to consent to increasing the amount of Secured Indebtedness under Credit Facilities that can be incurred from the greater of $9.0 billion and 150% of Consolidated Cash Flow to the greater of $9.0 billion and an amount that would not cause the Secured Debt to Cash Flow Ratio (calculated net of cash and cash equivalents) to exceed 2.00x (the “Ratio Secured Debt Proposed Amendments”) and in each case as such capitalized term is defined in the Indenture. In connection with receiving the requisite consents for the Ratio Secured Debt Proposed Amendments, we made upfront payments to third-party note holders of $17 million during the second quarter of 2018. These payments were recognized as a reduction to Long-term debt in our Consolidated Balance Sheets. These upfront payments increased the effective interest rate of the related debt. In addition, note holders agreed, among other things, to allow certain entities related to Sprint’s existing spectrum securitization notes program (“Existing Sprint Spectrum Program”) to be non-guarantor Restricted Subsidiaries, provided that the principal amount of the spectrum notes issued and outstanding under the Existing Sprint Spectrum Program does not exceed $7.0 billion and that the principal amount of such spectrum notes reduces the amount available under the Credit Facilities ratio basket, and to revise the definition of GAAP to mean generally accepted accounting principles in effect from time to time, unless the Company elects to “freeze” GAAP as of any date, and to exclude the effect of the changes in the accounting treatment of lease obligations (the “Existing Sprint Spectrum and GAAP Proposed Amendments,” and together with the Ratio Secured Debt Proposed Amendments, the “Proposed Amendments”). In connection with receiving the requisite consents for the Existing Sprint Spectrum and GAAP Proposed Amendments, we made upfront payments to third-party note holders of $14 million during the second quarter of 2018. These payments were recognized as a reduction to Long-term debt in our Consolidated Balance Sheets. These upfront payments increased the effective interest rate of the related debt. In connection with obtaining the requisite consents, on May 20, 2018, T-Mobile USA, the guarantors and Deutsche Bank Trust Company Americas, as trustee, executed and delivered the 37 th supplemental indenture to the Indenture, pursuant to which, with respect to each of the Notes, the Proposed Amendments will become effective immediately prior to the consummation of the Merger. We paid third-party bank fees associated with obtaining the requisite consents related to the Proposed Amendments of $6 million during the second quarter of 2018, which we recognized as Selling, general and administrative expenses in our Consolidated Statements of Comprehensive Income. If the Merger is consummated, we will make additional payments to third-party note holders for requisite consents related to the Ratio Secured Debt Proposed Amendments of up to $54 million and additional payments to third-party note holders for requisite consents related to the Existing Sprint Spectrum and GAAP Proposed Amendments of up to $41 million . There was no payment accrued as of December 31, 2018 . 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 2017 , we utilized and repaid $100 million under the financing arrangement. As of December 31, 2018 and 2017 , 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 2018 , we utilized and repaid $300 million under the financing arrangement. As of December 31, 2018 and 2017 , there was no outstanding balance. Revolving Credit Facility We have a $2.5 billion revolving credit facility with DT that is comprised of (i) a $1.0 billion unsecured revolving credit agreement (“Unsecured Revolving Credit Facility”) and (ii) a $1.5 billion secured revolving credit agreement (“Secured Revolving Credit Facility”). In January 2018, we utilized proceeds under our revolving credit facility with DT to redeem $1.0 billion in aggregate principal amount of our 6.125% Senior Notes due 2022 and for general corporate purposes. On January 29, 2018, the proceeds utilized under our revolving credit facility with DT were repaid. In March 2018, we amended the terms of our Unsecured Revolving Credit Facility and our Secured Revolving Credit Facility. Following these amendments, (i) the range of the applicable margin payable under the Unsecured Revolving Credit Facility is 2.05% to 3.05% , (ii) the range of applicable margin payable under the Secured Revolving Credit Facility is 1.05% to 1.80% , (iii) the range of the undrawn commitment fee applicable to the Unsecured Revolving Credit Facility is 0.20% to 0.575% , (iv) the range of the undrawn commitment fee applicable to the Secured Revolving Credit Facility is 0.25% to 0.45% , and (v) the maturity date of the revolving credit facility with DT is December 29, 2020. The amendments also modify the facility to update certain covenants and other provisions to make them substantially consistent, subject to certain additional carve outs, with our most recently issued public notes. In November 2018, we amended the terms of the revolving credit facility with DT to extend the maturity date to December 29, 2021. 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 . As of December 31, 2018 and 2017 , there were no outstanding borrowings under the revolving credit facility. Capital Leases Capital lease agreements primarily relate to network equipment with varying expiration terms through 2033 . 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, 2019 $ 909 2020 631 2021 389 2022 102 2023 66 Thereafter 106 Total $ 2,203 Included in Total Interest $ 143 Maintenance 45 Standby Letters of Credit 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 66 59 Total outstanding balance $ 86 $ 79

Tower Obligations

Tower Obligations	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Tower Obligations	Note 9 – 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 (the “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 (the “2015 Tower Transaction”). As of December 31, 2018 , rights to approximately 150 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 our 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 $ 329 $ 402 Long-term financial obligation 2,557 2,590 Future minimum payments related to the tower obligations are expected to be approximately $195 million in 2019 , $391 million in total for 2020 and 2021 , $392 million in total for 2022 and 2023 and $835 million 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 15 – Commitments and Contingencies for further information. If we conclude a sale should be recognized, upon adoption of the new lease standard on January 1, 2019, we would derecognize our existing long-term financial obligation and the net book value of the tower-related property and equipment associated with the previous failed sale-leaseback transaction. See Note 1 – Summary of Significant Accounting Policies for further information.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	Note 10 – Revenue from Contracts with Customers Disaggregation of Revenue We provide wireless communication services to three primary categories of customers: • Branded postpaid customers generally include customers who are qualified to pay after receiving wireless communication services utilizing phones, mobile broadband devices (including tablets), DIGITS, SyncUP DRIVE™ or other devices including wearables; • Branded prepaid customers generally include customers who pay for wireless communication services in advance. Our branded prepaid customers include customers of T-Mobile and Metro by T-Mobile; and • Wholesale customers include M2M and MVNO customers that operate on our network but are managed by wholesale partners. See Note 1 – Summary of Significant Accounting Policies for further discussion. Branded postpaid service revenues, including branded postpaid phone revenues and branded postpaid other revenues, were as follows: Year Ended December 31, (in millions) 2018 2017 2016 Branded postpaid service revenues Branded postpaid phone revenues $ 19,745 $ 18,371 $ 17,365 Branded postpaid other revenues 1,117 1,077 773 Total branded postpaid service revenues $ 20,862 $ 19,448 $ 18,138 We operate as a single operating segment. The balances presented within each revenue line item in our Consolidated Statements of Comprehensive Income represent categories of revenue from contracts with customers disaggregated by type of product and service. Service revenues also include revenues earned for providing value added services to customers, such as handset insurance services. Revenue generated from the lease of mobile communication devices and accessories is included within Equipment revenues in our Consolidated Statements of Comprehensive Income . Equipment revenues from the lease of mobile communication devices and accessories were as follows: Year Ended December 31, (in millions) 2018 2017 2016 Equipment revenues from the lease of mobile communication devices and accessories $ 692 $ 877 $ 1,416 Contract Balances The opening and closing balances of our contract asset and contract liability balances from contracts with customers as of January 1, 2018 and December 31, 2018 , were as follows: (in millions) Contract Assets Included in Other Current Assets Contract Liabilities Included in Deferred Revenue Balance as of January 1, 2018 $ 140 $ 718 Balance as of December 31, 2018 51 645 Change $ (89 ) $ (73 ) Contract assets primarily represent revenue recognized for equipment sales with promotional bill credits offered to customers that are paid over time and are contingent on the customer maintaining a service contract. The change in the contract asset balance includes customer activity related to new promotions, offset by billings on existing contracts and impairment which is recognized as bad debt expense. Contract liabilities are recorded when fees are collected, or we have an unconditional right to consideration (a receivable) in advance of delivery of goods or services. The change in contract liabilities is primarily related to customer activity associated with our prepaid plans including the receipt of cash payments and the satisfaction of our performance obligations. Revenues for the year ended December 31, 2018 , include the following: (in millions) Year Ended December 31, 2018 Amounts included in the January 1, 2018 contract liability balance $ 710 Amounts associated with performance obligations satisfied in previous periods 2 Remaining Performance Obligations As of December 31, 2018 , the aggregate amount of transaction price allocated to remaining service performance obligations for branded postpaid contracts with promotional bill credits that result in an extended service contract is $308 million . We expect to recognize this revenue as service is provided over the extended contract term in the next 24 months . Certain of our wholesale, roaming and other service contracts include variable consideration based on usage. This variable consideration has been excluded from the disclosure of remaining performance obligations. As of December 31, 2018 , the aggregate amount of the contractual minimum consideration allocated to remaining service performance obligations for wholesale, roaming and other service contracts is $1.1 billion , $1.0 billion and $1.5 billion for 2019 , 2020 and 2021 and beyond, respectively. These contracts have a remaining duration of less than one year to six years . Information about remaining performance obligations that are part of a contract that has an original expected duration of one year or less have been excluded from the above, which primarily consists of monthly service contracts. The aggregate amount of the transaction price allocated to remaining service performance obligations includes the estimated amount to be invoiced to the customer. Contract Costs The total balance of deferred incremental costs to obtain contracts as of December 31, 2018 was $644 million . Deferred contract costs incurred to obtain postpaid service contracts are amortized over a period of 24 months . The amortization period is monitored to reflect any significant change in assumptions. Amortization of deferred contract costs was $267 million for the year ended December 31, 2018 . The deferred contract cost asset is assessed for impairment on a periodic basis. There were no impairment losses recognized on deferred contract cost assets for the year ended December 31, 2018 .

Employee Compensation and Benef

Employee Compensation and Benefit Plans	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee Compensation and Benefit Plans	Note 11 – Employee Compensation and Benefit Plans On February 14, 2018, our Board of Directors adopted, and on June 13, 2018, our stockholders approved an amendment (the “Amendment”) to the 2013 Omnibus Incentive Plan (as amended, the “Plan”) which increased the number of shares authorized for issuance under the Plan by 18,500,000 shares. On June 18, 2018, we filed a Form S-8 to register a total of 19,345,005 shares of common stock pursuant to the Plan, representing those covered by the Amendment, certain other predecessor plans, and certain equity arrangements assumed in connection with the acquisition of Layer3 TV in January 2018. During the year ended December 31, 2018 , we granted or assumed an aggregate of 6,259,169 RSUs and restricted stock awards (“RSAs”) to eligible employees, certain non-employee directors, and eligible key executives, which primarily included annual awards. RSUs entitle the grantee to receive shares of our common stock at the end of a vesting period of generally up to three years , subject to continued service through the applicable vesting date. During the year ended December 31, 2018 , we granted an aggregate of 3,364,629 PRSUs to eligible key executives, which primarily included annual awards and an aggregate of 1,317,386 PRSUs to certain executive officers in connection with the entry into the Business Combination Agreement with Sprint. PRSUs entitle the holder to receive shares of our common stock at the end of a performance period of generally up to three years , based on the attainment of the applicable performance goals and generally subject to continued employment through the applicable performance 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. As discussed in Note 2 – Business Combinations , in January 2018 we completed our acquisition of Layer3 TV. The fair value of share-based incentive compensation awards attributable to post-combination services was approximately $30 million . 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 $ 424 $ 306 $ 235 Income tax benefit related to stock-based compensation 81 73 80 Weighted average fair value per stock award granted 61.52 60.21 45.07 Unrecognized compensation expense 547 445 389 Weighted average period to be recognized (years) 1.8 1.9 2.0 Fair value of stock awards vested 471 503 354 Stock Awards Time-Based Restricted Stock Units and Restricted Stock Awards (in millions, except shares, per share and contractual life amounts) Number of Units or Awards Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Nonvested, December 31, 2017 12,061,608 $ 50.69 1.1 $ 766 Granted 6,259,169 60.44 Vested 6,455,617 47.89 Forfeited 854,525 56.90 Nonvested, December 31, 2018 11,010,635 $ 57.66 1.0 $ 700 Performance-Based Restricted Stock Units and Restricted Stock Awards (in millions, except shares, per share and contractual life amounts) Number of Units or Awards Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Nonvested, December 31, 2017 1,633,935 $ 48.06 1.1 $ 104 Granted 3,364,629 63.54 Vested 1,006,769 36.47 Forfeited 140,241 64.14 Nonvested, December 31, 2018 3,851,554 $ 64.03 1.6 $ 245 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 shares of common 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 2,321,827 and 2,754,721 shares of common stock to cover tax obligations associated with the payment of shares upon vesting of stock awards and remitted cash of $146 million and $166 million to the appropriate tax authorities for the years ended December 31, 2018 and 2017 , respectively. Employee Stock Purchase Plan Our employee stock purchase plan (“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 2,011,794 and 1,832,043 for the years ended December 31, 2018 and 2017 , respectively. Stock Options Stock options outstanding relate to the Metro Communications, Inc. 2010 Equity Incentive Compensation Plan, the Amended and Restated Metro Communications, Inc. 2004 Equity Incentive Compensation Plan, the Second Amended and Restated 1995 Stock Option Plan and the Layer3 TV, Inc. 2013 Stock Plan (collectively, the “Stock Option Plans”). No new awards have been or may be granted under the Stock Option Plans. The following activity occurred under the Stock Option Plans: Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (Years) Outstanding and exercisable, December 31, 2017 373,158 $ 16.36 2.8 Assumed through acquisition of Layer3 TV 118,645 15.51 Exercised 187,965 18.28 Expired/canceled 19,027 18.81 Outstanding at December 31, 2018 284,811 14.58 3.8 Exercisable at December 31, 2018 244,224 14.18 3.1 Stock options exercised under the Stock Option Plans generated proceeds of approximately $3 million and $21 million for the years ended December 31, 2018 and 2017 , 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 $102 million , $87 million and $83 million for the years ended December 31, 2018 , 2017 and 2016 , 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, 2018 and 2017 , there were no LTIP awards outstanding and no new awards are expected to be granted under the LTIP. There was no compensation expense reported within operating expenses related to our LTIP for the years ended December 31, 2018 , 2017 and 2016 . There were no payments to participants related to our LTIP for the years ended December 31, 2018 and 2017 . Payments were $52 million for the year ended December 31, 2016 .

Repurchases of Common Stock

Repurchases of Common Stock	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Repurchases of Common Stock	Note 12 – Repurchases of Common Stock 2017 Stock Repurchase Program 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 (the “2017 Stock Repurchase Program”). Repurchased shares are retired. The 2017 Stock Repurchase Program completed on April 29, 2018. The following table summarizes information regarding repurchases of our common stock under the 2017 Stock Repurchase Program: (In millions, except shares and per share price) Year ended December 31 Number of Shares Repurchased Average Price Paid Per Share Total Purchase Price 2018 16,738,758 $ 62.96 $ 1,054 2017 7,010,889 63.34 444 23,749,647 $ 63.07 $ 1,498 2018 Stock Repurchase Program On April 27, 2018, our Board of Directors authorized an increase in the total stock repurchase program to $9.0 billion , consisting of the $1.5 billion in repurchases previously completed and for up to an additional $7.5 billion of repurchases of our common stock, allocated as up to $500 million of shares of common stock through December 31, 2018, up to $3.0 billion of shares of common stock for the year ending December 31, 2019 and up to $4.0 billion of shares of common stock for the year ending December 31, 2020, with any authorized but unutilized repurchase capacity for any of the foregoing periods increasing the authorized repurchase capacity for the succeeding period by the amount of such unutilized repurchase capacity. The additional $7.5 billion repurchase authorization is contingent upon the termination of the Business Combination Agreement and the abandonment of the transactions contemplated under the Business Combination Agreement. 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 SEC 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. Stock Purchases by Affiliate In the first quarter of 2018, DT, our majority stockholder and an affiliated purchaser, purchased 3.3 million additional shares of our common stock at an aggregate market value of $200 million in the public market or from other parties, in accordance with the rules of the SEC and other applicable legal requirements. There were no purchases in the remainder of 2018. We did not receive proceeds from these purchases.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Note 13 – Income Taxes Our sources of Income before income taxes were as follows: Year Ended December 31, (in millions) 2018 2017 2016 U.S. $ 3,686 $ 3,274 $ 2,286 Puerto Rico 231 (113 ) 41 Income before income taxes $ 3,917 $ 3,161 $ 2,327 Income tax expense is summarized as follows: Year Ended December 31, (in millions) 2018 2017 2016 Current tax benefit (expense) Federal $ 39 $ — $ 66 State (63 ) (28 ) (29 ) Puerto Rico (25 ) (1 ) 10 Total current tax benefit (expense) (49 ) (29 ) 47 Deferred tax benefit (expense) Federal (750 ) 1,182 (804 ) State (160 ) 173 (96 ) Puerto Rico (70 ) 49 (14 ) Total deferred tax (expense) benefit (980 ) 1,404 (914 ) Total income tax (expense) benefit $ (1,029 ) $ 1,375 $ (867 ) The reconciliation between the U.S. federal statutory income tax rate and our effective income tax rate is as follows: Year Ended December 31, 2018 2017 2016 Federal statutory income tax rate 21.0 % 35.0 % 35.0 % Effect of law and rate changes 1.9 (68.9 ) 0.8 Change in valuation allowance (1.6 ) (11.4 ) 1.0 State taxes, net of federal benefit 4.8 4.8 3.2 Equity-based compensation (0.6 ) (2.4 ) (2.2 ) Puerto Rico taxes, net of federal benefit 2.4 (1.5 ) — Permanent differences 1.3 0.5 0.6 Federal tax credits, net of reserves (2.9 ) 0.3 (0.5 ) Other, net — 0.1 (0.6 ) Effective income tax rate 26.3 % (43.5 )% 37.3 % 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 $ 1,526 $ 1,576 Deferred rents 784 759 Reserves and accruals 668 667 Federal and state tax credits 340 298 Other 620 403 Deferred tax assets, gross 3,938 3,703 Valuation allowance (210 ) (273 ) Deferred tax assets, net 3,728 3,430 Deferred tax liabilities Spectrum licenses 5,494 5,038 Property and equipment 2,434 1,840 Other intangible assets 40 41 Other 232 48 Total deferred tax liabilities 8,200 6,967 Net deferred tax liabilities $ 4,472 $ 3,537 Classified on the balance sheet as: Deferred tax liabilities $ 4,472 $ 3,537 In 2017, the SEC issued Staff Accounting Bulletin (“SAB”) No. 118 which permitted the recording of provisional amounts related to the impact of the U.S. Tax Cuts and Jobs Act of 2017 (the “TCJA”) during a measurement period not to exceed one year from the enactment date of the TCJA. We recorded an immaterial amount for provisional items related to the TCJA in our Consolidated Statements of Comprehensive Income for the year ended December 31, 2017. Our accounting for these items is now complete. Current period adjustments related to the provisional items were immaterial. As of December 31, 2018 , we have tax effected net operating loss (“NOL”) carryforwards of $1.1 billion for federal income tax purposes and $797 million for state income tax purposes, expiring through 2038. Federal NOLs and certain state NOLs generated in 2018 do not expire. As of December 31, 2018 , our tax effected federal and state NOL carryforwards for financial reporting purposes were approximately $119 million and $261 million , respectively, less than our NOL carryforwards for federal and state income tax purposes, due to unrecognized tax benefits of the same amount. The financial reporting amounts exclude indirect tax effects in other jurisdictions. As of December 31, 2018 , we have available Alternative Minimum Tax (“AMT”) credit carryforwards of $48 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 $312 million for federal income tax purposes, which begin to expire in 2019. As of December 31, 2018 , 2017 and 2016, our valuation allowance was $210 million , $273 million and $573 million , respectively. The change from December 31, 2017 to December 31, 2018 primarily related to a reduction in the valuation allowance against deferred tax assets in certain state jurisdictions from a change in tax status of certain subsidiaries. The change from December 31, 2016 to December 31, 2017 primarily related to a reduction in the valuation allowance against deferred tax assets in state jurisdictions of $359 million , 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. 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 examination 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 1999. A reconciliation of the beginning and ending amount of unrecognized tax benefits were as follows: Year Ended December 31, (in millions) 2018 2017 2016 Unrecognized tax benefits, beginning of year $ 412 $ 410 $ 411 Gross increases (decreases) to tax positions in prior periods 6 (10 ) (5 ) Gross increases due to current period business acquisitions 10 — — Gross increases to current period tax positions 34 12 4 Unrecognized tax benefits, end of year $ 462 $ 412 $ 410 As of December 31, 2018 and 2017 , we had $315 million and $254 million , respectively, in unrecognized tax benefits that, if recognized, would affect our annual effective tax rate. Included in the 2018 increase to unrecognized tax benefits is $10 million related to tax positions acquired through the acquisition of Layer3 TV. 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, 2018
Earnings Per Share [Abstract]
Earnings Per Share	Note 14 – 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) 2018 2017 2016 Net income $ 2,888 $ 4,536 $ 1,460 Less: Dividends on mandatory convertible preferred stock — (55 ) (55 ) Net income attributable to common stockholders - basic 2,888 4,481 1,405 Add: Dividends related to mandatory convertible preferred stock — 55 — Net income attributable to common stockholders - diluted $ 2,888 $ 4,536 $ 1,405 Weighted average shares outstanding - basic 849,744,152 831,850,073 822,470,275 Effect of dilutive securities: Outstanding stock options and unvested stock awards 8,546,022 9,200,873 10,584,270 Mandatory convertible preferred stock — 30,736,504 — Weighted average shares outstanding - diluted 858,290,174 871,787,450 833,054,545 Earnings per share - basic $ 3.40 $ 5.39 $ 1.71 Earnings per share - diluted $ 3.36 $ 5.20 $ 1.69 Potentially dilutive securities: Outstanding stock options and unvested stock awards 148,422 33,980 3,528,683 Mandatory convertible preferred stock — — 32,238,000 As of December 31, 2018 , we had authorized 100 million shares of 5.50% mandatory convertible preferred stock series A, with a par value of $0.00001 per share. There were no preferred shares outstanding as of December 31, 2018 and 2017 , respectively. 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, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 15 – 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 2028 . 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 2027 . Our commitments under these leases are approximately $2.7 billion for the year ending December 31, 2019 , $4.7 billion in total for the years ending December 31, 2020 and 2021 , $3.3 billion in total for the years ending December 31, 2022 and 2023 and $3.8 billion in total for years thereafter. As of December 31, 2018 , 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 9 – Tower Obligations for further information. Total rent expense under operating leases, including dedicated transportation lines, was $3.0 billion , $2.9 billion and $2.8 billion for the years ended December 31, 2018 , 2017 and 2016 , respectively, and is classified as Cost of services and Selling, general and administrative expense in our Consolidated Statements of Comprehensive Income . Purchase Commitments We have commitments for non-dedicated transportation lines with varying expiration terms through 2029 . In addition, we have commitments to purchase and lease spectrum licenses, wireless devices, network services, equipment, software, marketing sponsorship agreements and other items in the ordinary course of business, with various terms through 2043 . 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. Our purchase obligations are approximately $3.4 billion for the year ending December 31, 2019 , $2.8 billion in total for the years ending December 31, 2020 and 2021 , $1.8 billion in total for the years ending December 31, 2022 and 2023 and $1.4 billion in total for the years thereafter. In June 2018, we entered into an agreement for the purchase of network equipment totaling approximately $3.5 billion . Based on unavoidable spend, the minimum commitment under this agreement is $377 million as of December 31, 2018 . In September 2018, we amended an agreement with a third party to increase the total amount of network equipment to purchase by approximately $3.5 billion . Based on unavoidable spend, the minimum commitment under this agreement is $259 million as of December 31, 2018 . In September 2018, we signed a reciprocal long-term spectrum lease with Sprint that included a total commitment of $535 million and an offsetting amount to be received from Sprint for the lease of our spectrum. Lease payments began in the fourth quarter of 2018. The reciprocal long-term lease is a distinct transaction from the Merger. In October 2018, we entered into agreements with a third-party associated with a device upgrade program, trade-in services, and device protection products and services offered to our mobile communications customers, with initial terms of one to three years . Device protection products and services include reinsurance for device insurance policies and extended warranty contracts, mobile security applications, and technical support services. Interest rate lock derivatives In October 2018, we entered into interest rate lock derivatives with notional amounts of $9.6 billion These interest rate lock derivatives were designated as cash flow hedges to reduce variability in cash flows due to changes in interest payments attributable to increases or decreases in the benchmark interest rate during the period leading up to the probable issuance of fixed-rate debt. The fair value of interest rate lock derivatives as of December 31, 2018 was $447 million and is included in Other current liabilities in our Consolidated Balance Sheets . See Note 7 – Fair Value Measurements for further information. Renewable Energy Purchase Agreements During 2018, T-Mobile USA entered four renewable energy purchase agreements (“REPAs”) with third parties. The REPAs are based on the expected operation of energy-generating facilities and will remain in effect for terms of between 15 and 20 years from the commencement of facility’s entry into commercial operation. Commercial operations are set to begin at the end of 2019 or 2020. Each REPA consists of an energy forward agreement that is net settled based on energy prices and the energy output generated by the facility. We have determined that each of the REPAs 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 REPAs do not contain any unconditional purchase obligations because amounts under the agreement are not fixed and determinable. Our participations in the REPAs did not require upfront investments or capital commitments. We do not control the activities that most significantly impact the energy-generating facilities, nor do we receive specific energy output from them. Contingencies and Litigation Litigation Matters We are involved in various lawsuits and disputes, 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, 2018
Supplemental Financial Statement Elements [Abstract]
Additional Financial Information	Note 16 – 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 $ 5,487 $ 6,182 Payroll and related benefits 709 614 Property and other taxes, including payroll 642 620 Interest 227 253 Commissions 243 324 Network decommissioning 65 92 Toll and interconnect 157 109 Advertising 76 46 Other 135 288 Accounts payable and accrued liabilities $ 7,741 $ 8,528 Book overdrafts included in accounts payable and accrued liabilities were $630 million and $455 million as of December 31, 2018 and 2017 , respectively. Hurricane Impacts During 2018, we recognized $61 million in costs related to hurricanes, including $36 million in incremental costs to maintain services primarily in Puerto Rico related to hurricanes that occurred in 2017 and $25 million related to hurricanes that occurred in 2018. Additional costs related to a hurricane that occurred in 2018 are expected to be immaterial in the first quarter of 2019. During 2018, we received reimbursement payments from our insurance carriers of $307 million related to hurricanes, of which $93 million was previously accrued for as a receivable as of December 31, 2017. We have accrued insurance recoveries related to a hurricane that occurred in 2018 of approximately $5 million for the year ended December 31, 2018 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. The following table shows the hurricane impacts in our Consolidated Statements of Comprehensive Income for the years ended December 31, 2018 and 2017 . There were no significant hurricane impacts in 2016 . Year Ended December 31, 2018 Year Ended December 31, 2017 (in millions, except per share amounts) Gross Reim- Net Gross Reim- Net Increase (decrease) Revenues Branded postpaid revenues $ — $ — $ — $ (37 ) $ — $ (37 ) Of which, postpaid phone revenues — — — (35 ) — (35 ) Branded prepaid revenues — — — (11 ) — (11 ) Total service revenues — — — (48 ) — (48 ) Equipment revenues — — — (8 ) — (8 ) Other revenues — 71 71 — — — Total revenues — 71 71 (56 ) — (56 ) Operating expenses Cost of services 59 (135 ) (76 ) 198 (93 ) 105 Cost of equipment sales 1 — 1 4 — 4 Selling, general and administrative 1 (13 ) (12 ) 36 — 36 Of which, bad debt expense — — — 20 — 20 Total operating expenses 61 (148 ) (87 ) 238 (93 ) 145 Operating income (loss) $ (61 ) $ 219 $ 158 $ (294 ) $ 93 $ (201 ) Net income (loss) $ (41 ) $ 140 $ 99 $ (193 ) $ 63 $ (130 ) Earnings per share - basic $ (0.05 ) $ 0.17 $ 0.12 $ (0.23 ) $ 0.07 $ (0.16 ) Earnings per share - diluted (0.05 ) 0.17 0.12 (0.22 ) 0.07 (0.15 ) Supplemental Consolidated Statements of Comprehensive Income Information Related Party Transactions We have related party transactions associated with DT 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 DT or its affiliates included in Operating expenses in the Consolidated Statements of Comprehensive Income : Year Ended December 31, (in millions) 2018 2017 2016 Discount related to roaming expenses $ — $ — $ (15 ) Fees incurred for use of the T-Mobile brand 84 79 74 Expenses for telecommunications and IT services — 12 25 International long distance agreement 36 55 60 We have an agreement with DT for the reimbursement of certain administrative expenses, which were $11 million for each of the years ended December 31, 2018 , 2017 and 2016 .

Guarantor Financial Information

Guarantor Financial Information	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Guarantor Financial Information	Note 17 – Guarantor Financial Information Pursuant to the applicable indentures and supplemental indentures, the long-term debt to affiliates and third parties 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”). See Note 8 – 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. On October 23, 2018, SLMA LLC was formed as a limited liability company in Delaware to serve as an escrow subsidiary to facilitate the contemplated issuance of notes by Parent in connection with the Transactions. SLMA LLC is an indirect, 100% owned finance subsidiary of Parent, as such term is used in Rule 3-10(b) of Regulation S-X, and has been designated as an unrestricted subsidiary under Issuer’s existing debt securities. Any debt securities that may be issued from time to time by SLMA LLC will be fully and unconditionally guaranteed by Parent. Presented below is the condensed consolidating financial information as of December 31, 2018 and 2017 , and for the years ended December 31, 2018 , 2017 and 2016 . Condensed Consolidating Balance Sheet Information December 31, 2018 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Assets Current assets Cash and cash equivalents $ 2 $ 1 $ 1,079 $ 121 $ — $ 1,203 Accounts receivable, net — — 1,510 259 — 1,769 Equipment installment plan receivables, net — — 2,538 — — 2,538 Accounts receivable from affiliates — — 11 — — 11 Inventories — — 1,084 — — 1,084 Other current assets — — 1,031 645 — 1,676 Total current assets 2 1 7,253 1,025 — 8,281 Property and equipment, net (1) — — 23,062 297 — 23,359 Goodwill — — 1,683 218 — 1,901 Spectrum licenses — — 35,559 — — 35,559 Other intangible assets, net — — 116 82 — 198 Investments in subsidiaries, net 25,314 46,516 — — (71,830 ) — Intercompany receivables and note receivables — 5,174 — — (5,174 ) — Equipment installment plan receivables due after one year, net — — 1,547 — — 1,547 Other assets — 7 1,540 221 (145 ) 1,623 Total assets $ 25,316 $ 51,698 $ 70,760 $ 1,843 $ (77,149 ) $ 72,468 Liabilities and Stockholders' Equity Current liabilities Accounts payable and accrued liabilities $ — $ 228 $ 7,240 $ 273 $ — $ 7,741 Payables to affiliates — 157 43 — — 200 Short-term debt — — 841 — — 841 Deferred revenue — — 698 — — 698 Other current liabilities — 447 164 176 — 787 Total current liabilities — 832 8,986 449 — 10,267 Long-term debt — 10,950 1,174 — — 12,124 Long-term debt to affiliates — 14,582 — — — 14,582 Tower obligations (1) — — 384 2,173 — 2,557 Deferred tax liabilities — — 4,617 — (145 ) 4,472 Deferred rent expense — — 2,781 — — 2,781 Negative carrying value of subsidiaries, net — — 676 — (676 ) — Intercompany payables and debt 598 — 4,234 342 (5,174 ) — Other long-term liabilities — 20 926 21 — 967 Total long-term liabilities 598 25,552 14,792 2,536 (5,995 ) 37,483 Total stockholders' equity (deficit) 24,718 25,314 46,982 (1,142 ) (71,154 ) 24,718 Total liabilities and stockholders' equity $ 25,316 $ 51,698 $ 70,760 $ 1,843 $ (77,149 ) $ 72,468 (1) Assets and liabilities for Non-Guarantor Subsidiaries are primarily included in VIEs related to the 2012 Tower Transaction. See Note 9 – Tower Obligations for further 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 9 – Tower Obligations for further information. Condensed Consolidating Statement of Comprehensive Income Information Year Ended December 31, 2018 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Revenues Service revenues $ — $ — $ 30,631 $ 2,339 $ (978 ) $ 31,992 Equipment revenues — — 10,208 2 (201 ) 10,009 Other revenues — 29 1,113 228 (61 ) 1,309 Total revenues — 29 41,952 2,569 (1,240 ) 43,310 Operating expenses Cost of services, exclusive of depreciation and amortization shown separately below — — 6,257 50 — 6,307 Cost of equipment sales — — 11,238 1,011 (202 ) 12,047 Selling, general and administrative — 11 13,203 985 (1,038 ) 13,161 Depreciation and amortization — — 6,396 90 — 6,486 Gains on disposal of spectrum licenses — — — — — — Total operating expense — 11 37,094 2,136 (1,240 ) 38,001 Operating (loss) income — 18 4,858 433 — 5,309 Other income (expense) Interest expense — (528 ) (114 ) (193 ) — (835 ) Interest expense to affiliates — (522 ) (21 ) — 21 (522 ) Interest income — 23 16 1 (21 ) 19 Other (expense) income, net — (87 ) 33 — — (54 ) Total other (expense) income, net — (1,114 ) (86 ) (192 ) — (1,392 ) Income (loss) before income taxes — (1,096 ) 4,772 241 — 3,917 Income tax expense — — (981 ) (48 ) — (1,029 ) Earnings of subsidiaries 2,888 3,984 32 — (6,904 ) — Net income $ 2,888 $ 2,888 $ 3,823 $ 193 $ (6,904 ) $ 2,888 Dividends on preferred stock — — — — — — Net income attributable to common stockholders $ 2,888 $ 2,888 $ 3,823 $ 193 $ (6,904 ) $ 2,888 Net income $ 2,888 $ 2,888 $ 3,823 $ 193 $ (6,904 ) $ 2,888 Other comprehensive income, net of tax Other comprehensive income, net of tax (332 ) (332 ) 116 — 216 (332 ) Total comprehensive income $ 2,556 $ 2,556 $ 3,939 $ 193 $ (6,688 ) $ 2,556 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 expenses — — 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 income (expense), net — (88 ) 16 (1 ) — (73 ) Total other expense, net 1 (1,430 ) (106 ) (192 ) — (1,727 ) Income (loss) before income taxes 1 (1,427 ) 4,407 180 — 3,161 Income tax 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 Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Revenues Service revenues $ — $ — $ 26,613 $ 2,023 $ (792 ) $ 27,844 Equipment revenues — — 9,145 — (418 ) 8,727 Other revenues — 3 739 195 (18 ) 919 Total revenues — 3 36,497 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 3,826 221 — 4,050 Other income (expense) Interest expense — (1,147 ) (82 ) (189 ) — (1,418 ) Interest expense to affiliates — (312 ) — — — (312 ) Interest income — 31 (18 ) — — 13 Other income (expense), net — 2 (8 ) — — (6 ) Total other expense, net — (1,426 ) (108 ) (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 Condensed Consolidating Statement of Cash Flows Information Year Ended December 31, 2018 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Operating activities Net cash (used in) provided by operating activities $ — $ (1,254 ) $ 10,483 $ (5,110 ) $ (220 ) $ 3,899 Investing activities Purchases of property and equipment — — (5,505 ) (36 ) — (5,541 ) Purchases of spectrum licenses and other intangible assets — — (127 ) — — (127 ) Proceeds related to beneficial interests in securitization transactions — — 53 5,353 — 5,406 Acquisition of companies, net of cash acquired — — (338 ) — — (338 ) Equity investment in subsidiary — — (43 ) — 43 — Other, net — (7 ) 28 — — 21 Net cash (used in) provided by investing activities — (7 ) (5,932 ) 5,317 43 (579 ) Financing activities Proceeds from issuance of long-term debt — 2,494 — — — 2,494 Proceeds from borrowing on revolving credit facility, net — 6,265 — — — 6,265 Repayments of revolving credit facility — — (6,265 ) — — (6,265 ) Repayments of capital lease obligations — — (698 ) (2 ) — (700 ) Repayments of short-term debt for purchases of inventory, property and equipment, net — — (300 ) — — (300 ) Repayments of long-term debt — — (3,349 ) — — (3,349 ) Repurchases of common stock (1,071 ) — — — — (1,071 ) Intercompany advances, net 995 (7,498 ) 6,468 35 — — Equity investment from parent — — — 43 (43 ) — Tax withholdings on share-based awards — — (146 ) — — (146 ) Cash payments for debt prepayment or debt extinguishment costs — — (212 ) — — (212 ) Intercompany dividend paid — — — (220 ) 220 — Other, net 4 — (56 ) — — (52 ) Net cash (used in) provided by financing activities (72 ) 1,261 (4,558 ) (144 ) 177 (3,336 ) Change in cash and cash equivalents (72 ) — (7 ) 63 — (16 ) Cash and cash equivalents Beginning of period 74 1 1,086 58 — 1,219 End of period $ 2 $ 1 $ 1,079 $ 121 $ — $ 1,203 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 ) $ 9,761 $ (4,218 ) $ (100 ) $ 3,831 Investing activities Purchases of property and equipment — — (5,237 ) — — (5,237 ) Purchases of spectrum licenses and other intangible assets — — (5,828 ) — — (5,828 ) Proceeds related to beneficial interests in securitization transactions — — 43 4,276 — 4,319 Equity investment in subsidiary (308 ) — — — 308 — Other, net — — 1 — — 1 Net cash (used in) provided by investing activities (308 ) — (11,021 ) 4,276 308 (6,745 ) 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 ) Repurchases of common stock (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 ) Dividends on preferred stock (55 ) — — — — (55 ) Cash payments for debt prepayment or debt extinguishment costs — — (188 ) — — (188 ) Intercompany dividend paid — — — (100 ) 100 — Other, net 21 — (16 ) — — 5 Net cash provided by (used in) financing activities 23 (1,119 ) 4 (67 ) (208 ) (1,367 ) 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 Balances have been revised based on the guidance in ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments.” See Note 1 – Summary of Significant Accounting Policies for further information. 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 ) $ 7,516 $ (3,298 ) $ (110 ) $ 2,779 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 ) Proceeds related to beneficial interests in securitization transactions — — 25 3,331 — — 3,356 Sales of short-term investments — 2,000 998 — — — 2,998 Other, net — — (8 ) — — (8 ) Net cash provided by (used in) investing activities — 2,000 (7,655 ) 3,331 — (2,324 ) 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 — — Tax withholdings on share-based awards — — (121 ) — — (121 ) Dividends on preferred stock (55 ) — — — — (55 ) Intercompany dividend paid — — — (110 ) 110 — Other, net 29 — (12 ) — — 17 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 Balances have been revised based on the guidance in ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments.” See Note 1 – Summary of Significant Accounting Policies of the Notes to the Consolidated Financial Statements, for further information.

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information [Abstract]
Quarterly Financial Information (Unaudited)	Supplementary Data Quarterly Financial Information (Unaudited) (in millions, except share and per share amounts) First Quarter Second Quarter Third Quarter Fourth Quarter Full Year 2018 Total revenues $ 10,455 $ 10,571 $ 10,839 $ 11,445 $ 43,310 Operating income 1,282 1,450 1,440 1,137 5,309 Net income 671 782 795 640 2,888 Net income attributable to common stockholders 671 782 795 640 2,888 Earnings per share Basic $ 0.78 $ 0.92 $ 0.94 $ 0.75 $ 3.40 Diluted 0.78 0.92 0.93 0.75 3.36 Weighted average shares outstanding Basic 855,222,664 847,660,488 847,087,120 849,102,785 849,744,152 Diluted 862,244,084 852,040,670 853,852,764 856,344,347 858,290,174 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 869,395,984 870,457,181 871,420,065 871,501,578 871,787,450 Net income includes: Gains on disposal of spectrum licenses (37 ) (1 ) (29 ) (168 ) (235 ) In December 2017, the TCJA was signed into legislation. The TCJA included numerous changes to existing tax law, including a permanent reduction in the federal corporate income tax rate from 35% to 21%. The rate reduction took place on January 1, 2018. We recognized a net tax benefit of $2.2 billion associated with the enactment of the TCJA in Income tax (expense) benefit 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. 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 Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
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 Metro™ by T-Mobile (“Metro by T-Mobile”), in the United States (“U.S.”), Puerto Rico and the U.S. Virgin Islands. All of our revenues were earned in, and all of our long-lived assets are located in, the 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 Accounting	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 standalone 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, fair value 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.
Use of Estimates	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 these estimates.
Reclassification	Certain prior year amounts have been reclassified to conform to the current year’s presentation. See “Accounting Pronouncements Adopted in the Current Year” below.
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 Allowances 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 our Consolidated Balance Sheets 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 36 months using an EIP. EIP receivables not held for sale are reported in our Consolidated Balance Sheets 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 if the EIP term exceeds 12 months as there is no stated rate of interest on the EIP receivables. The EIP receivables are recorded at their present value, which is determined by discounting future cash payments at the imputed interest rate. The difference between the recorded amount of the EIP receivables and their unpaid principal balance (i.e., the contractual amount due from the customer) results in a discount which is allocated to the performance obligation of the arrangement and recorded as a reduction in transaction price in Total service revenues and 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 credit loss allowance at the time of issuance as the effects of uncertainty about future cash flows resulting from credit risk 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. Total imputed discount and allowances was approximately 8.1% of the total amount of gross accounts receivable, including EIP receivables at both December 31, 2018 and 2017. 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 and Property and Equipment	Long-Lived Assets Long-lived assets include assets that do not have indefinite lives, such as property and equipment and other intangible assets. All of our long-lived assets are located in the U.S., including Puerto Rico and the U.S. Virgin Islands. 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 depreciable 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. JUMP! On Demand 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 that the fair value of the two reporting units, wireless business and Layer3 TV, 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 that 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. 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 are recognized as either assets or liabilities and are measured at fair value. We do not use derivatives for trading or speculative purposes. For derivative instruments designated as cash flow hedges, changes in fair value are reported as a component of Accumulated other comprehensive income (“AOCI”) until reclassified into Interest expense in the same period the hedged transaction affects earnings, generally over the life of the related debt. Unrealized gains on derivatives designated as cash flow hedges are recorded at fair value as assets, and unrealized losses on derivatives designated as cash flow hedges are recorded at fair value as liabilities. We have 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.
Revenue Recognition	Revenue Recognition (effective January 1, 2018) We primarily generate our revenue from providing wireless services to customers and selling or leasing devices and accessories. Our contracts with customers may involve multiple performance obligations, which include wireless services, wireless devices or a combination thereof, and we allocate the transaction price between each performance obligation based on its relative standalone selling price. Significant Judgments The most significant judgments affecting the amount and timing of revenue from contracts with our customers include the following items: • Revenue for service contracts that we assess are not probable of collection is not recognized until the contract is completed and cash is received. Collectibility is re-assessed when there is a significant change in facts or circumstances. Our assessment of collectibility considers whether we may limit our exposure to credit risk through our right to stop transferring additional service in the event the customer is delinquent as well as certain contract terms such as down payments that reduce our exposure to credit risk. Customer credit behavior is inherently uncertain. See “Receivables and Allowance for Credit Losses”, above, for more discussion on how we assess credit risk. • Promotional EIP bill credits offered to a customer on an equipment sale that are paid over time and are contingent on the customer maintaining a service contract may result in an extended service contract based on whether a substantive penalty is deemed to exist. Determining whether contingent EIP bill credits result in a substantive termination penalty may require significant judgment. • The identification of distinct performance obligations within our service plans may require significant judgment. • Revenue is recorded net of costs paid to another party for performance obligations where we arrange for the other party to transfer goods or services to the customer (i.e., when we are acting as an agent). For example, performance obligations relating to services provided by third-party content providers where we neither controls a right to the content provider’s service nor controls the underlying service itself are presented net because we are acting as an agent. The determination of whether we control the underlying service or right to the service prior to our transfer to the customer requires, at times, significant judgment. • For transactions where we recognize a significant financing component, judgment is required to determine the discount rate. For EIP sales, the discount rate used to adjust the transaction price primarily reflects current market interest rates and the estimated credit risk of the customer. Customer credit behavior is inherently uncertain. See “Receivables and Allowance for Credit Losses”, above, for more discussion on how we assess credit risk. • Our products are generally sold with a right of return, which is accounted for as variable consideration when estimating the amount of revenue to recognize. Device return levels are estimated based on the expected value method as there are a large number of contracts with similar characteristics and the outcome of each contract is independent of the others. Historical return rate experience is a significant input to our expected value methodology. • Sales of equipment to indirect dealers who have been identified as our customer (referred to as the sell-in model) often include credits subsequently paid to the dealer as a reimbursement for any discount promotions offered to the end consumer. These credits (payments to a customer) are accounted for as variable consideration when estimating the amount of revenue to recognize from the sales of equipment to indirect dealers and are estimated based on historical experience and other factors, such as expected promotional activity. • The determination of the standalone selling price for contracts that involve more than one performance obligation may require significant judgment, such as when the selling price of a good or service is not readily observable. • For capitalized contract costs, determining the amortization period over which such costs are recognized as well as assessing the indicators of impairment may require significant judgment. Wireless Services Revenue We generate our wireless services 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 contracts are billed monthly either in advance or arrears, or are prepaid. Generally, service revenue is recognized as we satisfy our performance obligation to transfer service to our customers. We typically satisfy our stand-ready performance obligations, including unlimited wireless services, evenly over the contract term. For usage-based and prepaid wireless services, we satisfy our performance obligations when services are rendered. Revenue for service contracts that we assess are not probable of collection is not recognized until the contract is completed and cash is received. Collectibility is re-assessed when there is a significant change in facts or circumstances. Our assessment of collectibility considers whether we may limit our exposure to credit risk through our right to stop transferring additional service in the event the customer is delinquent. Consideration payable to a customer is treated as a reduction of the total transaction price, unless the payment is in exchange for a distinct good or service, such as certain commissions paid to dealers. Revenue is recorded net of costs paid to another party for performance obligations where we arrange for the other party to transfer goods or services to the customer (i.e., when we are acting as an agent). For example, performance obligations relating to services provided by third-party content providers where we neither controls a right to the content provider’s service nor controls the underlying service itself are presented net because we are acting as an agent. Federal Universal Service Fund (“USF”) and other regulatory fees are assessed by various governmental authorities in connection with the services we provide to our customers and are included in Cost of services. When we separately bill and collect these regulatory fees from customers, they are recorded gross in Total service revenues in our Consolidated Statements of Comprehensive Income . For the years ended December 31, 2018, 2017 and 2016, we recorded approximately $161 million , $258 million and $409 million , respectively, of USF fees on a gross basis. We have made an accounting policy election to exclude from the measurement of the transaction price all taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction and collected by us from a customer (for example, sales, use, value added, and some excise taxes). Equipment Revenues We generate equipment revenues from the sale or lease of mobile communication devices and accessories. For performance obligations related to equipment contracts, we typically transfer control at a point in time when the device or accessory is delivered to, and accepted by, the customer or dealer. We have elected to account for shipping and handling activities that occur after control of the related good transfers as fulfillment activities instead of assessing such activities as performance obligations. We estimate variable consideration (e.g., device returns or certain payments to indirect dealers) primarily based on historical experience. Equipment sales not probable of collection are generally recorded as payments are received. Our assessment of collectibility considers contract terms such as down payments that reduce our exposure to credit risk. We offer certain customers the option to pay for devices and accessories in installments using an EIP. Generally, we recognize as a reduction of the total transaction price the effects of a financing component in contracts where customers purchase their devices and accessories on an EIP with a term of more than one year, including those financing components that are not considered to be significant to the contract. However, we have elected the practical expedient to not recognize the effects of a significant financing component for contracts where we expect, at contract inception, that the period between the transfer of a performance obligation to a customer and the customer’s payment for that performance obligation will be one year or less. In addition, for customers who enroll in our JUMP! program, we recognize a liability based on the estimated fair value of the specified-price trade-in right guarantee. The fair value of the guarantee is deducted from the transaction price and the remaining transaction price is allocated to other elements of the contract, including service and equipment performance obligations. See “Guarantee Liabilities” above for further information. JUMP! On Demand 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 wireless devices are accounted for as operating leases and estimated contract consideration is allocated between lease elements and non-lease elements (such as service and equipment performance obligations) based on the relative standalone selling price of each performance obligation in the contract. Lease revenues are recorded as equipment revenues and recognized as earned on a straight-line basis over the lease term. Lease revenues on contracts not probable of collection are limited to the amount of payments received. See “Property and Equipment” above for further information. Contract Balances Generally, our devices and service plans are available at standard prices, which are maintained on price lists and published on our website and/or within our retail stores. For contracts that involve more than one product or service that are identified as separate performance obligations, the transaction price is allocated to the performance obligations based on their relative standalone selling prices. The standalone selling price is the price at which we would sell the good or service separately to a customer and is most commonly evidenced by the price at which we sell that good or service separately in similar circumstances and to similar customers. A contract asset is recorded when revenue is recognized in advance of our right to receive consideration (i.e., we must perform additional services in order to receive consideration). Amounts are recorded as receivables when our right to consideration is unconditional. When consideration is received, or we have an unconditional right to consideration in advance of delivery of goods or services, a contract liability is recorded. The transaction price can include non-refundable upfront fees, which are allocated to the identifiable performance obligations. Contract assets are included in Other current assets and Other assets and contract liabilities are included in Deferred revenue in our Consolidated Balance Sheets . Contract Modifications Our service contracts allow customers to frequently modify their contracts without incurring penalties in many cases. Each time a contract is modified, we evaluate the change in scope or price of the contract to determine if the modification should be treated as a separate contract, as if there is a termination of the existing contract and creation of a new contract, or if the modification should be considered a change associated with the existing contract. We typically do not have significant impacts from contract modifications. Contract Costs We incur certain incremental costs to obtain a contract that we expect to recover, such as sales commissions. We record an asset when these incremental costs to obtain a contract are incurred and amortize them on a systematic basis that is consistent with the transfer to the customer of the goods or services to which the asset relates. We amortize deferred costs incurred to obtain service contracts on a straight-line basis over the term of the initial contract and anticipated renewal contracts to which the costs relate, currently 24 months . However, we have elected the practical expedient permitting expensing of costs to obtain a contract when the expected amortization period is one year or less. Incremental costs to obtain equipment contracts (e.g., commissions paid on device and accessory sales) are recognized when the equipment is transferred to the customer. See Note 1 - Summary of Significant Accounting Policies included in our Annual Report on Form 10-K for the year ended December 31, 2017 for more discussion regarding the accounting policies that governed revenue recognition prior to January 1, 2018.
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.
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 cash flow hedges and available-for-sale securities. This is reported in AOCI 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.
Variable Interest Entities	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 Revenue In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers (Topic 606),” and has since modified the standard with several ASUs (collectively, the “new revenue standard”). The new revenue 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. We adopted the new revenue standard on January 1, 2018, using the modified retrospective method with the cumulative effect of initially applying the guidance recognized at the date of initial application. Comparative information has not been restated and continues to be reported under the standards in effect for those periods. We have applied the new revenue standard only to contracts not completed as of the date of initial application, referred to as open contracts. We have elected the practical expedient that permits an entity to reflect the aggregate effect of all of the modifications (on a contract-by-contract basis) that occurred before the date of initial application in determining the transaction price, identifying the satisfied and unsatisfied performance obligations, and allocating the transaction price to the performance obligations. Electing this practical expedient does not have a significant impact on our financial statements due to the short-term duration of most of our contracts and the nature of our contract modifications. We have implemented significant new revenue accounting systems, processes and internal controls over revenue recognition to assist us in the application of the new revenue standard. Financial Statement Impacts of Applying the New Revenue Standard The cumulative effect of initially applying the new revenue standard to all open contracts as of January 1, 2018 is as follows: January 1, 2018 (in millions) Beginning Balance Cumulative Effect Adjustment Beginning Balance, As Adjusted Assets Other current assets $ 1,903 $ 140 $ 2,043 Other assets 912 150 1,062 Liabilities and Stockholders’ Equity Deferred revenue $ 779 $ 4 $ 783 Deferred tax liabilities 3,537 73 3,610 Accumulated deficit (16,074 ) 213 (15,861 ) The most significant impacts upon adoption of the new revenue standard on January 1, 2018 include the following items: • A deferred contract cost asset of $150 million was recorded at transition in Other assets in our Consolidated Balance Sheets for incremental contract acquisition costs paid on open contracts, which consists primarily of commissions paid to acquire branded postpaid service contracts; and • A contract asset of $140 million was recorded at transition in Other current assets in our Consolidated Balance Sheets primarily for contracts with promotional bill credits offered to customers on equipment sales that are paid over time and are contingent on the customer maintaining a service contract. Financial statement results as reported under the new revenue standard as compared to the previous revenue standard for the year ended December 31, 2018 are as follows: Year Ended December 31, 2018 (in millions, except per share amounts) Previous Revenue Standard New Revenue Standard Change Revenues Branded postpaid revenues $ 20,887 $ 20,862 $ (25 ) Branded prepaid revenues 9,608 9,598 (10 ) Wholesale revenues 1,183 1,183 — Roaming and other service revenues 349 349 — Total service revenues 32,027 31,992 (35 ) Equipment revenues 9,616 10,009 393 Other revenues 1,309 1,309 — Total revenues 42,952 43,310 358 Operating expenses Cost of services, exclusive of depreciation and amortization shown separately below 6,233 6,307 74 Cost of equipment sales 12,065 12,047 (18 ) Selling, general and administrative 13,257 13,161 (96 ) Depreciation and amortization 6,486 6,486 — Total operating expenses 38,041 38,001 (40 ) Operating income 4,911 5,309 398 Total other expense, net (1,392 ) (1,392 ) — Income before income taxes 3,519 3,917 398 Income tax expense (926 ) (1,029 ) (103 ) Net income $ 2,593 $ 2,888 $ 295 Earnings per share Basic earnings per share 3.05 3.40 0.35 Diluted earnings per share 3.02 3.36 0.34 December 31, 2018 (in millions) Previous Revenue Standard New Revenue Standard Change Assets Other current assets $ 1,625 $ 1,676 $ 51 Other assets 979 1,623 644 Liabilities and Stockholders’ Equity Deferred revenue $ 685 $ 698 $ 13 Deferred tax liabilities 4,297 4,472 175 Accumulated deficit (13,461 ) (12,954 ) 507 The most significant impacts to financial statement results as reported under the new revenue standard as compared to the previous revenue standard for the current reporting period are as follows: • Under the new revenue standard, certain commissions paid to dealers previously recognized as a reduction to Equipment revenues in our Consolidated Statements of Comprehensive Income are now recorded as commission costs in Selling, general and administrative expense. • Contract costs capitalized for new contracts accumulated in Other assets in our Consolidated Balance Sheets during 2018. As a result, there was a net benefit to Operating income in our Consolidated Statements of Comprehensive Income during 2018 as capitalization of costs exceeded amortization. As capitalized costs amortize into expense over time, the accretive benefit to Operating income is expected to moderate in 2019 and normalize in 2020. • Certain promotions previously recognized as a reduction in Equipment revenues in our Consolidated Statements of Comprehensive Income are now recorded as a reduction in Service revenues. • Certain revenues previously recognized as Equipment revenues in our Consolidated Statements of Comprehensive Income are now recorded as Service revenues. • Certain contract fulfillment costs have been reclassified to Cost of services in our Consolidated Statements of Comprehensive Income from Selling, general and administrative expenses. • Wholesale revenues for minimum guaranteed amounts (guarantee shortfall) are recognized when it is probable that a reversal of such revenue will not occur, which may impact the timing of recognition as compared to the previous standard. • For contracts with promotional bill credits that are contingent on the customer maintaining a service contract that result in an extended service contract, a contract asset is recorded when control of the equipment transfers to the customer and is subsequently amortized as a reduction to Total service revenues in our Consolidated Statements of Comprehensive Income over the extended contract term. See disclosures related to Contracts with Customers under the new revenue standard in Note 10 – Revenue from Contracts with Customers . Statement of Cash Flows On January 1, 2018, we adopted ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments” (the “new cash flow standard”) which impacted the presentation of our cash flows related to our 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 $5.4 billion , $4.3 billion , and $3.4 billion for the years ended December 31, 2018 , 2017 and 2016 , respectively, in our Consolidated Statements of Cash Flows . The new cash flow standard also impacted the presentation of our cash payments for debt prepayment and debt extinguishment costs, resulting in a reclassification of cash outflows from Operating activities to Financing activities of $212 million and $188 million for the years ended December 31, 2018 and 2017 , respectively, in our Consolidated Statements of Cash Flows . There were no cash payments for debt prepayment and debt extinguishment costs during the year ended December 31, 2016 . We have applied the new cash flow standard retrospectively to all periods presented. Financial Instruments In January 2016, the FASB issued ASU 2016-01, “Financial Instruments (Topic 825): Recognition and Measurement of Financial Assets and Financial Liabilities,” and has since modified the standard in February 2018 with ASU 2018-03, “Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities”. The standard addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. The standard became effective for us, and we adopted the standard, on January 1, 2018. The standard requires the impact of adoption to be recorded to retained earnings under a modified retrospective approach, resulting in a reclassification of Accumulated other comprehensive income to Accumulated deficit of $8 million . Income Taxes In October 2016, the FASB issued ASU 2016-16, “Accounting for Income Taxes (Topic 740): 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 became effective for us, and we adopted the standard, on January 1, 2018. The standard requires any deferred taxes not yet recognized on intra-entity transfers to be recorded to retained earnings under a modified retrospective approach, resulting in an adjustment to Accumulated deficit of $11 million . Derivatives and Hedging In August 2017, the FASB issued ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvement to Accounting for Hedging Activities” (the “new derivatives and hedging standard”). The standard modified the guidance for the designation and measurement of qualifying hedging relationships and the presentation of hedge results. We adopted this standard on October 1, 2018 and have applied the standard to hedging transactions prospectively. Accounting Pronouncements Not Yet Adopted Leases In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842),” and has since modified the standard with several ASUs (collectively, the “new lease standard”). The standard is effective for us, and we adopted the standard, on January 1, 2019. The new lease standard requires most lessees to report a right-of-use asset and a lease liability. The income statement recognition is similar to existing lease accounting and is based on lease classification. The new lease standard requires lessees and lessors to classify most leases using principles similar to existing lease accounting. For lessors, the new lease standard modifies the classification criteria and the accounting for sales-type and direct financing leases. The new lease standard provides entities two options for applying the modified retrospective approach, either (1) retrospectively to each prior reporting period presented in the financial statements with the cumulative-effect adjustment recognized at the beginning of the earliest comparative period presented or (2) retrospectively at the beginning of the period of adoption (January 1, 2019) through a cumulative-effect adjustment. We plan to adopt the standard by recognizing and measuring leases at the adoption date with a cumulative effect of initially applying the guidance recognized at the date of initial application. The new standard provides for a number of optional practical expedients in transition. We do not expect to elect the “package of practical expedients” and as a result we would be required to reassess under the new standard our prior accounting conclusions about lease identification, lease classification and initial direct costs. We do expect to elect the use of hindsight for determining the reasonably certain lease term. We do not expect to elect the practical expedient pertaining to land easements as it is not applicable to us. Upon the adoption of the new lease standard entities are required to reassess any previous failed sale-leaseback transactions that remain failed as of the effective date of the new standard. This reassessment should consider if a sale would have occurred as of the beginning of the reporting period in which the entity applies the new lease standard. Under the new lease standard, a sale is assessed using the transfer of control criteria in the new revenue standard. If the revised sale-leaseback guidance criteria are met and a sale has occurred as of the effective date, the gain or loss on the sale of the underlying asset is recognized as an adjustment to equity and the accounting for the leaseback will follow the transition provisions provided for all other operating leases. We expect the most significant judgments and impacts upon adoption of the standard to include the following items: • Upon adoption on January 1, 2019, we will recognize right-of-use assets and lease liabilities that have not previously been recorded. The lease liability for operating leases is based on the net present value of future minimum lease payments. The right-of-use asset for operating leases is based on the lease liability adjusted for the reclassification of certain balance sheet amounts such as deferred rent, subsequent to re-measurement from the assessment of lease term described below, and prepaid rent. Deferred and prepaid rent will not be presented separately after the adoption of the new lease standard. • We expect to elect the use of hindsight in determining the expected lease term for all cell sites and have generally concluded to include only payments due for the initial non-cancelable lease term. This assessment of expected lease term corresponds to our lease term assessment for new leases and aligns with the payments that have been disclosed as lease commitments in prior years. As a result, the average remaining lease term for cell sites has decreased from approximately 9 years to 4 years based on lease contracts in effect at transition on January 1, 2019. • We are also required to reassess the previously failed sale-leaseback of certain T-Mobile-owned wireless communication tower sites and determine whether the transfer of the assets to the tower operator under the arrangement met the transfer of control criteria in the new revenue standard and whether a sale should be recognized. We are continuing to finalize our assessment of the previously failed sale-leaseback. If we conclude a sale should be recognized, upon adoption on January 1, 2019, we would derecognize our existing long-term financial obligation and the net book value of the tower-related property and equipment associated with the previously failed sale-leaseback transaction. A change in the sale-leaseback accounting conclusion would also result in the recognition of a lease liability and right of use asset for the leaseback, decreases in Other revenues and Interest expense and a reclassification of certain cash payments from financing outflows to operating outflows in our Consolidated Statements of Cash Flows. • Excluding the impacts of a potential change in the accounting conclusion around the previously failed sale leaseback, the cumulative effects of initially applying the new lease standard on January 1, 2019 and for fiscal year 2019 would be as follows: • The cumulative effect of initially applying the new lease standard on January 1, 2019 is estimated to be an increase in total assets of $8.5 billion to $9.4 billion , an increase in total liabilities of $8.2 billion to $8.9 billion and a decrease to Accumulated deficit of $300 million to $500 million . • The aggregate impact is expected to result in a decrease in Total operating expenses of $190 million to $230 million and an increase to Net income of $140 million to $180 million in fiscal year 2019. • Including the impacts that would result from a change in the accounting conclusion on the previously failed sale-leaseback, the cumulative effects of initially applying the new lease standard on January 1, 2019 and for fiscal year 2019 would be as follows: • The cumulative effect of initially applying the new lease standard on January 1, 2019 is estimated to be an increase in total assets of $9.1 billion to $10.0 billion , an increase in total liabilities of $7.0 billion to $7.5 billion and a decrease to Accumulated deficit of $2.1 billion to $2.5 billion . • The aggregate impact is expected to result in a decrease in Other revenues of $230 million to $250 million , a decrease in Interest expense of $200 million to $240 million , a decrease in Total operating expense s of $220 million to $260 million and an increase to Net income of $140 million to $180 million in fiscal year 2019. • The expected impact on our Consolidated Statements of Cash Flows in fiscal year 2019 is a decrease in Net cash provided by operating activities of $20 million to $40 million and a decrease in Net cash used in financing activities of $20 million to $40 million . The new lease standard provides practical expedients and policy elections for an entity’s ongoing accounting. We currently expect to elect the practical expedient to not separate lease and non-lease components for all of our leases. We do not expect to elect the short-term lease recognition exemption, which includes the recognition of right-of-use assets and lease liabilities for existing short-term leases at transition. For arrangements where we are the lessor, we do not expect the adoption of the new lease standard to have a material impact on our financial statements as all of our leases are operating leases. The new lease standard provides a practical expedient for lessors in which the lessor may elect, by class of underlying asset, to not separate non-lease components from the associated lease component and, instead, to account for these components as a single component if both of the following are met: (1) the timing and pattern of transfer of the non-lease component(s) and associated lease component are the same and (2) the lease component, if accounted for separately, would be classified as an operating lease. We do not expect to elect this expedient for leased wireless devices under our JUMP! On Demand program. We are in the process of implementing significant new lease accounting systems and are updating processes and implementing new internal controls over lease recognition to assist in the application of the new lease standard. Financial Instruments In June 2016, the FASB issued ASU 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” In November 2018, the FASB issued ASU 2018-19, “Codification Improvements to Topic 326, Financial Instruments-Credit Losses,” which amends the scope and transition requirements of ASU 2016-13. 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. Cloud Computing Arrangements In August 2018, the FASB issued ASU 2018-15, “Intangibles - Goodwill and Other - Internal-Use Software (Topic 350): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract.” The standard aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The standard will become effective for us beginning January 1, 2020 and can be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. Early adoption is permitted for us at any time. We are currently evaluating the impact this guidance will have on our Consolidated Financial Statements and the timing of adoption. Other recent accounting pronouncements issued by the FASB (including its Emerging Issues Task Force), the American Institute of Certified Public Accountants, and the Securities and Exchange Commission (the “SEC”) did not have, or are not believed by management to have, a significant impact on our present or future Consolidated Financial Statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Financial Statement Impacts of Applying New Accounting Standard	The cumulative effect of initially applying the new revenue standard to all open contracts as of January 1, 2018 is as follows: January 1, 2018 (in millions) Beginning Balance Cumulative Effect Adjustment Beginning Balance, As Adjusted Assets Other current assets $ 1,903 $ 140 $ 2,043 Other assets 912 150 1,062 Liabilities and Stockholders’ Equity Deferred revenue $ 779 $ 4 $ 783 Deferred tax liabilities 3,537 73 3,610 Accumulated deficit (16,074 ) 213 (15,861 ) Financial statement results as reported under the new revenue standard as compared to the previous revenue standard for the year ended December 31, 2018 are as follows: Year Ended December 31, 2018 (in millions, except per share amounts) Previous Revenue Standard New Revenue Standard Change Revenues Branded postpaid revenues $ 20,887 $ 20,862 $ (25 ) Branded prepaid revenues 9,608 9,598 (10 ) Wholesale revenues 1,183 1,183 — Roaming and other service revenues 349 349 — Total service revenues 32,027 31,992 (35 ) Equipment revenues 9,616 10,009 393 Other revenues 1,309 1,309 — Total revenues 42,952 43,310 358 Operating expenses Cost of services, exclusive of depreciation and amortization shown separately below 6,233 6,307 74 Cost of equipment sales 12,065 12,047 (18 ) Selling, general and administrative 13,257 13,161 (96 ) Depreciation and amortization 6,486 6,486 — Total operating expenses 38,041 38,001 (40 ) Operating income 4,911 5,309 398 Total other expense, net (1,392 ) (1,392 ) — Income before income taxes 3,519 3,917 398 Income tax expense (926 ) (1,029 ) (103 ) Net income $ 2,593 $ 2,888 $ 295 Earnings per share Basic earnings per share 3.05 3.40 0.35 Diluted earnings per share 3.02 3.36 0.34 December 31, 2018 (in millions) Previous Revenue Standard New Revenue Standard Change Assets Other current assets $ 1,625 $ 1,676 $ 51 Other assets 979 1,623 644 Liabilities and Stockholders’ Equity Deferred revenue $ 685 $ 698 $ 13 Deferred tax liabilities 4,297 4,472 175 Accumulated deficit (13,461 ) (12,954 ) 507

Business Combinations (Tables)

Business Combinations (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of Amounts Recognized as of Acquisition Date	The following table shows the amounts recognized as of the IWS Acquisition Date for each major class of assets acquired and liabilities assumed and the resultant purchase price allocation: (in millions) January 1, Assets acquired Current assets Cash and cash equivalents $ 3 Accounts receivable, net 6 Equipment installment plan receivables, net 3 Inventories 1 Other current assets 2 Current assets, total 15 Property and equipment, net 36 Spectrum licenses 87 Total assets acquired $ 138 Liabilities assumed Accounts payable and accrued liabilities $ 6 Deferred revenue 2 Current liabilities, total 8 Deferred tax liabilities 17 Other long-term liabilities 7 Total long-term liabilities 24 Net assets acquired $ 106 The following table shows the amounts recognized as of the acquisition date for each major class of assets acquired and liabilities assumed and the resultant purchase price allocation: (in millions) January 22, Assets acquired Cash and cash equivalents $ 2 Other current assets 14 Property and equipment, net 11 Intangible assets 100 Goodwill 218 Deferred tax assets 2 Total assets acquired $ 347 Liabilities assumed Accounts payable and accrued liabilities $ 27 Short-term debt 2 Total liabilities assumed 29 Total consideration transferred $ 318
Schedule of Consideration Transferred	The following table highlights the consideration transferred, the fair value of our previously held equity interest and bargain purchase: (in millions) January 1, Consideration transferred: Cash paid $ 25 Previously held equity interest: Acquisition date fair value of previously held equity interest 56 Bargain purchase gain 25 Net assets acquired $ 106

Receivables and Allowance for_2

Receivables and Allowance for Credit Losses (Tables)	12 Months Ended
	Dec. 31, 2018
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 $ 4,534 $ 3,960 Unamortized imputed discount (330 ) (264 ) EIP receivables, net of unamortized imputed discount 4,204 3,696 Allowance for credit losses (119 ) (132 ) EIP receivables, net $ 4,085 $ 3,564 Classified on the balance sheet as: Equipment installment plan receivables, net $ 2,538 $ 2,290 Equipment installment plan receivables due after one year, net 1,547 1,274 EIP receivables, net $ 4,085 $ 3,564
Schedule of Unamortized Imputed Discount and Allowance for Credit Losses for Equipment Installment Plan Receivables	Activity for the years ended December 31, 2018 , 2017 and 2016 in the allowance for credit losses and unamortized imputed discount balances for the accounts receivable and EIP receivables segments were as follows: December 31, 2018 December 31, 2017 December 31, 2016 (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 $ 86 $ 396 $ 482 $ 102 $ 316 $ 418 $ 116 $ 333 $ 449 Bad debt expense 69 228 297 104 284 388 227 250 477 Write-offs, net of recoveries (88 ) (240 ) (328 ) (120 ) (273 ) (393 ) (241 ) (277 ) (518 ) Change in imputed discount on short-term and long-term EIP receivables N/A 250 250 N/A 252 252 N/A 186 186 Impact on the imputed discount from sales of EIP receivables N/A (185 ) (185 ) N/A (183 ) (183 ) N/A (176 ) (176 ) Allowance for credit losses and imputed discount, end of period $ 67 $ 449 $ 516 $ 86 $ 396 $ 482 $ 102 $ 316 $ 418
Schedule of Equipment Installment Plan Receivables by Credit Category	The following table provides delinquency status for the unpaid principal balance for receivables within the EIP portfolio segment, which we actively monitor as part of our current credit risk management practices and policies: December 31, 2018 December 31, 2017 (in millions) Prime Subprime Total EIP Receivables, gross Prime Subprime Total EIP Receivables, gross Current - 30 days past due $ 1,987 $ 2,446 $ 4,433 $ 1,727 $ 2,133 $ 3,860 31 - 60 days past due 15 32 47 17 29 46 61 - 90 days past due 6 19 25 6 16 22 More than 90 days past due 7 22 29 8 24 32 Total receivables, gross $ 2,015 $ 2,519 $ 4,534 $ 1,758 $ 2,202 $ 3,960

Sales of Certain Receivables (T

Sales of Certain Receivables (Tables)	12 Months Ended
	Dec. 31, 2018
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 $ 339 $ 236 Accounts payable and accrued liabilities 59 25 Other current liabilities 149 180
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 $ 321 $ 403 Other assets 88 109 Other long-term liabilities 22 3
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 $ 2,577 $ 2,725 Other current assets 660 639 of which, deferred purchase price 658 636 Other long-term assets 88 109 of which, deferred purchase price 88 109 Accounts payable and accrued liabilities 59 25 Other current liabilities 149 180 Other long-term liabilities 22 3 Net cash proceeds since inception 1,879 2,058 Of which: Change in net cash proceeds during the year-to-date period (179 ) 28 Net cash proceeds funded by reinvested collections 2,058 2,030

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
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 $ 2,423 $ 2,066 Wireless communications systems Up to 20 years 35,282 32,706 Leasehold improvements Up to 12 years 1,299 1,182 Capitalized software Up to 10 years 11,712 10,563 Leased devices Up to 18 months 1,164 1,209 Construction in progress 2,776 1,771 Accumulated depreciation and amortization (31,297 ) (27,301 ) Property and equipment, net $ 23,359 $ 22,196
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 $ 1,159 $ 1,209 Accumulated depreciation (622 ) (417 ) Leased wireless devices, net $ 537 $ 792
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, 2019 $ 419 2020 59 Total $ 478
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 $ 562 $ 539 Liabilities incurred 26 25 Liabilities settled (9 ) (16 ) Accretion expense 30 27 Changes in estimated cash flows — (13 ) Asset retirement obligations, end of year $ 609 $ 562 Classified on the balance sheet as: Other current liabilities $ — $ 3 Other long-term liabilities 609 559 Asset retirement obligations $ 609 $ 562

Goodwill, Spectrum License Tr_2

Goodwill, Spectrum License Transactions and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The changes in the carrying amount of goodwill for the years ended December 31, 2018 and 2017 are as follows: (in millions) Goodwill Historical goodwill $ 12,449 Accumulated impairment losses at December 31, 2017 (10,766 ) Balance as of December 31, 2017 1,683 Goodwill from acquisition of Layer3 TV 218 Balance as of December 31, 2018 $ 1,901 Accumulated impairment losses at December 31, 2018 $ (10,766 )
Schedule of Spectrum Licenses	The following table summarizes our spectrum license activity for the years ended December 31, 2018 and 2017 : (in millions) 2018 2017 Spectrum licenses, beginning of year $ 35,366 $ 27,014 Spectrum license acquisitions 138 8,599 Spectrum licenses transferred to held for sale (1 ) (271 ) Costs to clear spectrum 56 24 Spectrum licenses, end of year $ 35,559 $ 35,366
Schedule of Other Intangible Assets	The components of Other intangible assets were as follows: Useful Lives December 31, 2018 December 31, 2017 (in millions) Gross Amount Accumulated Amortization Net Amount Gross Amount Accumulated Amortization Net Amount Customer lists Up to 6 years $ 1,104 $ (1,086 ) $ 18 $ 1,104 $ (1,016 ) $ 88 Trademarks and patents Up to 19 years 312 (225 ) 87 307 (192 ) 115 Other Up to 28 years 149 (56 ) 93 49 (35 ) 14 Other intangible assets $ 1,565 $ (1,367 ) $ 198 $ 1,460 $ (1,243 ) $ 217
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, 2019 $ 73 2020 55 2021 35 2022 25 2023 6 Thereafter 4 Total $ 198

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Carrying Values and Fair Values of Long-term Debt	The carrying amounts and fair values of our assets 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, 2018 December 31, 2017 (in millions) Carrying Amount Fair Value Carrying Amount Fair Value Assets: Deferred purchase price assets 3 $ 746 $ 746 $ 745 $ 745 The carrying 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, 2018 December 31, 2017 (in millions) Carrying Amount Fair Value Carrying Amount Fair Value Liabilities: Senior Notes to third parties 1 $ 10,950 $ 10,945 $ 11,910 $ 12,540 Senior Notes to affiliates 2 9,984 9,802 7,486 7,852 Incremental Term Loan Facility to affiliates 2 4,000 3,976 4,000 4,020 Senior Reset Notes to affiliates 2 598 640 3,100 3,260

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Debt	Debt was as follows: (in millions) December 31, December 31, 8.097% Senior Reset Notes to affiliates due 2021 $ — $ 1,250 5.300% Senior Notes to affiliates due 2021 2,000 2,000 8.195% Senior Reset Notes to affiliates due 2022 — 1,250 4.000% Senior Notes to affiliates due 2022 1,000 1,000 4.000% Senior Notes due 2022 500 500 6.125% Senior Notes due 2022 — 1,000 Incremental term loan facility to affiliates due 2022 2,000 2,000 6.000% Senior Notes due 2023 1,300 1,300 6.625% Senior Notes due 2023 — 1,750 6.836% Senior Notes due 2023 — 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 1,350 6.000% Senior Notes to affiliates due 2024 650 650 Incremental term loan facility to affiliates due 2024 2,000 2,000 5.125% Senior Notes to affiliates due 2025 1,250 1,250 5.125% Senior Notes due 2025 500 500 6.375% Senior Notes due 2025 1,700 1,700 6.500% Senior Notes due 2026 2,000 2,000 4.500% Senior Notes due 2026 1,000 — 4.500% Senior Notes to affiliates due 2026 1,000 — 5.375% Senior Notes due 2027 500 500 5.375% Senior Notes to affiliates due 2027 1,250 1,250 4.750% Senior Notes due 2028 1,500 — 4.750% Senior Notes to affiliates due 2028 1,500 — Capital leases 2,015 1,824 Unamortized premium from purchase price allocation fair value adjustment — 78 Unamortized premium on debt to affiliates 52 59 Unamortized discount on Senior Notes to affiliates (64 ) (73 ) Debt issuance costs and consent fees (56 ) (19 ) Total debt 27,547 28,319 Less: Current portion of Senior Notes — 999 Less: Current portion of capital leases 841 613 Total long-term debt $ 26,706 $ 26,707 Classified on the balance sheet as: Long-term debt $ 12,124 $ 12,121 Long-term debt to affiliates 14,582 14,586 Total long-term debt $ 26,706 $ 26,707 During the year ended December 31, 2018 we issued the following Senior Notes: (in millions) Principal Issuances Issuance Costs Net Proceeds from Issuance of Long-Term Debt Issue Date 4.500% Senior Notes due 2026 $ 1,000 $ 2 $ 998 January 25, 2018 4.750% Senior Notes due 2028 1,500 4 1,496 January 25, 2018 Total of Senior Notes issued $ 2,500 $ 6 $ 2,494 We used the net proceeds of $2.5 billion from the transaction to refinance existing indebtedness to DT as follows: (in millions) Principal Amount Write -off of Embedded Derivatives (1) Other (2) Redemption Redemption Price 8.097% Senior Notes due 2021 $ 1,250 $ (8 ) $ 51 April 28, 2018 104.0485 % 8.195% Senior Notes due 2022 1,250 (8 ) 51 April 28, 2018 104.0975 % Total $ 2,500 $ (16 ) $ 102 (1) Certain components of the reset features were required to be bifurcated from the DT Senior Reset Notes and separately accounted for as embedded derivative instruments. Write-off of embedded derivatives are included in Losses on redemption of debt within Net cash provided by operating activities in our Consolidated Statements of Cash Flows . (2) Cash for 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.
Debt Instrument Redemption	During the year ended December 31, 2018 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 6.125% Senior Notes due 2022 $ 1,000 $ 1 $ 31 January 15, 2018 103.063 % 6.625% Senior Notes due 2023 1,750 (75 ) 58 April 1, 2018 103.313 % 6.836% Senior Notes due 2023 600 — 21 April 28, 2018 103.418 % (1) Write-off of premiums, discounts, issuance costs and call penalties are included in Other income (expense), net in our Consolidated Statements of Comprehensive Income . Write-off of premiums, discounts and issuance costs are included in Losses on redemption of debt 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 (used in) provided by financing 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, 2019 $ 909 2020 631 2021 389 2022 102 2023 66 Thereafter 106 Total $ 2,203 Included in Total Interest $ 143 Maintenance 45
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 66 59 Total outstanding balance $ 86 $ 79

Tower Obligations (Tables)

Tower Obligations (Tables)	12 Months Ended
	Dec. 31, 2018
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 $ 329 $ 402 Long-term financial obligation 2,557 2,590

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	Branded postpaid service revenues, including branded postpaid phone revenues and branded postpaid other revenues, were as follows: Year Ended December 31, (in millions) 2018 2017 2016 Branded postpaid service revenues Branded postpaid phone revenues $ 19,745 $ 18,371 $ 17,365 Branded postpaid other revenues 1,117 1,077 773 Total branded postpaid service revenues $ 20,862 $ 19,448 $ 18,138 Equipment revenues from the lease of mobile communication devices and accessories were as follows: Year Ended December 31, (in millions) 2018 2017 2016 Equipment revenues from the lease of mobile communication devices and accessories $ 692 $ 877 $ 1,416
Schedule of Contract Liability and Receivable Balances	Revenues for the year ended December 31, 2018 , include the following: (in millions) Year Ended December 31, 2018 Amounts included in the January 1, 2018 contract liability balance $ 710 Amounts associated with performance obligations satisfied in previous periods 2 The opening and closing balances of our contract asset and contract liability balances from contracts with customers as of January 1, 2018 and December 31, 2018 , were as follows: (in millions) Contract Assets Included in Other Current Assets Contract Liabilities Included in Deferred Revenue Balance as of January 1, 2018 $ 140 $ 718 Balance as of December 31, 2018 51 645 Change $ (89 ) $ (73 )

Employee Compensation and Ben_2

Employee Compensation and Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2018
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 $ 424 $ 306 $ 235 Income tax benefit related to stock-based compensation 81 73 80 Weighted average fair value per stock award granted 61.52 60.21 45.07 Unrecognized compensation expense 547 445 389 Weighted average period to be recognized (years) 1.8 1.9 2.0 Fair value of stock awards vested 471 503 354
Schedule of RSU and PRSU Awards Activity	Time-Based Restricted Stock Units and Restricted Stock Awards (in millions, except shares, per share and contractual life amounts) Number of Units or Awards Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Nonvested, December 31, 2017 12,061,608 $ 50.69 1.1 $ 766 Granted 6,259,169 60.44 Vested 6,455,617 47.89 Forfeited 854,525 56.90 Nonvested, December 31, 2018 11,010,635 $ 57.66 1.0 $ 700 Performance-Based Restricted Stock Units and Restricted Stock Awards (in millions, except shares, per share and contractual life amounts) Number of Units or Awards Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Nonvested, December 31, 2017 1,633,935 $ 48.06 1.1 $ 104 Granted 3,364,629 63.54 Vested 1,006,769 36.47 Forfeited 140,241 64.14 Nonvested, December 31, 2018 3,851,554 $ 64.03 1.6 $ 245 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 Stock Option Plans: Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (Years) Outstanding and exercisable, December 31, 2017 373,158 $ 16.36 2.8 Assumed through acquisition of Layer3 TV 118,645 15.51 Exercised 187,965 18.28 Expired/canceled 19,027 18.81 Outstanding at December 31, 2018 284,811 14.58 3.8 Exercisable at December 31, 2018 244,224 14.18 3.1

Repurchases of Common Stock (Ta

Repurchases of Common Stock (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of Repurchases of Common Stock	The following table summarizes information regarding repurchases of our common stock under the 2017 Stock Repurchase Program: (In millions, except shares and per share price) Year ended December 31 Number of Shares Repurchased Average Price Paid Per Share Total Purchase Price 2018 16,738,758 $ 62.96 $ 1,054 2017 7,010,889 63.34 444 23,749,647 $ 63.07 $ 1,498

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
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) 2018 2017 2016 U.S. $ 3,686 $ 3,274 $ 2,286 Puerto Rico 231 (113 ) 41 Income before income taxes $ 3,917 $ 3,161 $ 2,327
Schedule of Components of Income Tax Expense (Benefit)	Income tax expense is summarized as follows: Year Ended December 31, (in millions) 2018 2017 2016 Current tax benefit (expense) Federal $ 39 $ — $ 66 State (63 ) (28 ) (29 ) Puerto Rico (25 ) (1 ) 10 Total current tax benefit (expense) (49 ) (29 ) 47 Deferred tax benefit (expense) Federal (750 ) 1,182 (804 ) State (160 ) 173 (96 ) Puerto Rico (70 ) 49 (14 ) Total deferred tax (expense) benefit (980 ) 1,404 (914 ) Total income tax (expense) benefit $ (1,029 ) $ 1,375 $ (867 )
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, 2018 2017 2016 Federal statutory income tax rate 21.0 % 35.0 % 35.0 % Effect of law and rate changes 1.9 (68.9 ) 0.8 Change in valuation allowance (1.6 ) (11.4 ) 1.0 State taxes, net of federal benefit 4.8 4.8 3.2 Equity-based compensation (0.6 ) (2.4 ) (2.2 ) Puerto Rico taxes, net of federal benefit 2.4 (1.5 ) — Permanent differences 1.3 0.5 0.6 Federal tax credits, net of reserves (2.9 ) 0.3 (0.5 ) Other, net — 0.1 (0.6 ) Effective income tax rate 26.3 % (43.5 )% 37.3 %
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 $ 1,526 $ 1,576 Deferred rents 784 759 Reserves and accruals 668 667 Federal and state tax credits 340 298 Other 620 403 Deferred tax assets, gross 3,938 3,703 Valuation allowance (210 ) (273 ) Deferred tax assets, net 3,728 3,430 Deferred tax liabilities Spectrum licenses 5,494 5,038 Property and equipment 2,434 1,840 Other intangible assets 40 41 Other 232 48 Total deferred tax liabilities 8,200 6,967 Net deferred tax liabilities $ 4,472 $ 3,537 Classified on the balance sheet as: Deferred tax liabilities $ 4,472 $ 3,537
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) 2018 2017 2016 Unrecognized tax benefits, beginning of year $ 412 $ 410 $ 411 Gross increases (decreases) to tax positions in prior periods 6 (10 ) (5 ) Gross increases due to current period business acquisitions 10 — — Gross increases to current period tax positions 34 12 4 Unrecognized tax benefits, end of year $ 462 $ 412 $ 410

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2018
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) 2018 2017 2016 Net income $ 2,888 $ 4,536 $ 1,460 Less: Dividends on mandatory convertible preferred stock — (55 ) (55 ) Net income attributable to common stockholders - basic 2,888 4,481 1,405 Add: Dividends related to mandatory convertible preferred stock — 55 — Net income attributable to common stockholders - diluted $ 2,888 $ 4,536 $ 1,405 Weighted average shares outstanding - basic 849,744,152 831,850,073 822,470,275 Effect of dilutive securities: Outstanding stock options and unvested stock awards 8,546,022 9,200,873 10,584,270 Mandatory convertible preferred stock — 30,736,504 — Weighted average shares outstanding - diluted 858,290,174 871,787,450 833,054,545 Earnings per share - basic $ 3.40 $ 5.39 $ 1.71 Earnings per share - diluted $ 3.36 $ 5.20 $ 1.69 Potentially dilutive securities: Outstanding stock options and unvested stock awards 148,422 33,980 3,528,683 Mandatory convertible preferred stock — — 32,238,000

Additional Financial Informat_2

Additional Financial Information (Tables)	12 Months Ended
	Dec. 31, 2018
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 $ 5,487 $ 6,182 Payroll and related benefits 709 614 Property and other taxes, including payroll 642 620 Interest 227 253 Commissions 243 324 Network decommissioning 65 92 Toll and interconnect 157 109 Advertising 76 46 Other 135 288 Accounts payable and accrued liabilities $ 7,741 $ 8,528
Schedule of Hurricane Impacts	There were no significant hurricane impacts in 2016 . Year Ended December 31, 2018 Year Ended December 31, 2017 (in millions, except per share amounts) Gross Reim- Net Gross Reim- Net Increase (decrease) Revenues Branded postpaid revenues $ — $ — $ — $ (37 ) $ — $ (37 ) Of which, postpaid phone revenues — — — (35 ) — (35 ) Branded prepaid revenues — — — (11 ) — (11 ) Total service revenues — — — (48 ) — (48 ) Equipment revenues — — — (8 ) — (8 ) Other revenues — 71 71 — — — Total revenues — 71 71 (56 ) — (56 ) Operating expenses Cost of services 59 (135 ) (76 ) 198 (93 ) 105 Cost of equipment sales 1 — 1 4 — 4 Selling, general and administrative 1 (13 ) (12 ) 36 — 36 Of which, bad debt expense — — — 20 — 20 Total operating expenses 61 (148 ) (87 ) 238 (93 ) 145 Operating income (loss) $ (61 ) $ 219 $ 158 $ (294 ) $ 93 $ (201 ) Net income (loss) $ (41 ) $ 140 $ 99 $ (193 ) $ 63 $ (130 ) Earnings per share - basic $ (0.05 ) $ 0.17 $ 0.12 $ (0.23 ) $ 0.07 $ (0.16 ) Earnings per share - diluted (0.05 ) 0.17 0.12 (0.22 ) 0.07 (0.15 )
Schedule of Related Party Transactions	The following table summarizes the impact of significant transactions with DT or its affiliates included in Operating expenses in the Consolidated Statements of Comprehensive Income : Year Ended December 31, (in millions) 2018 2017 2016 Discount related to roaming expenses $ — $ — $ (15 ) Fees incurred for use of the T-Mobile brand 84 79 74 Expenses for telecommunications and IT services — 12 25 International long distance agreement 36 55 60

Guarantor Financial Informati_2

Guarantor Financial Information (Tables)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Schedule of Condensed Consolidating Balance Sheet Information	Condensed Consolidating Balance Sheet Information December 31, 2018 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Assets Current assets Cash and cash equivalents $ 2 $ 1 $ 1,079 $ 121 $ — $ 1,203 Accounts receivable, net — — 1,510 259 — 1,769 Equipment installment plan receivables, net — — 2,538 — — 2,538 Accounts receivable from affiliates — — 11 — — 11 Inventories — — 1,084 — — 1,084 Other current assets — — 1,031 645 — 1,676 Total current assets 2 1 7,253 1,025 — 8,281 Property and equipment, net (1) — — 23,062 297 — 23,359 Goodwill — — 1,683 218 — 1,901 Spectrum licenses — — 35,559 — — 35,559 Other intangible assets, net — — 116 82 — 198 Investments in subsidiaries, net 25,314 46,516 — — (71,830 ) — Intercompany receivables and note receivables — 5,174 — — (5,174 ) — Equipment installment plan receivables due after one year, net — — 1,547 — — 1,547 Other assets — 7 1,540 221 (145 ) 1,623 Total assets $ 25,316 $ 51,698 $ 70,760 $ 1,843 $ (77,149 ) $ 72,468 Liabilities and Stockholders' Equity Current liabilities Accounts payable and accrued liabilities $ — $ 228 $ 7,240 $ 273 $ — $ 7,741 Payables to affiliates — 157 43 — — 200 Short-term debt — — 841 — — 841 Deferred revenue — — 698 — — 698 Other current liabilities — 447 164 176 — 787 Total current liabilities — 832 8,986 449 — 10,267 Long-term debt — 10,950 1,174 — — 12,124 Long-term debt to affiliates — 14,582 — — — 14,582 Tower obligations (1) — — 384 2,173 — 2,557 Deferred tax liabilities — — 4,617 — (145 ) 4,472 Deferred rent expense — — 2,781 — — 2,781 Negative carrying value of subsidiaries, net — — 676 — (676 ) — Intercompany payables and debt 598 — 4,234 342 (5,174 ) — Other long-term liabilities — 20 926 21 — 967 Total long-term liabilities 598 25,552 14,792 2,536 (5,995 ) 37,483 Total stockholders' equity (deficit) 24,718 25,314 46,982 (1,142 ) (71,154 ) 24,718 Total liabilities and stockholders' equity $ 25,316 $ 51,698 $ 70,760 $ 1,843 $ (77,149 ) $ 72,468 (1) Assets and liabilities for Non-Guarantor Subsidiaries are primarily included in VIEs related to the 2012 Tower Transaction. See Note 9 – Tower Obligations for further 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 9 – 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, 2018 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Revenues Service revenues $ — $ — $ 30,631 $ 2,339 $ (978 ) $ 31,992 Equipment revenues — — 10,208 2 (201 ) 10,009 Other revenues — 29 1,113 228 (61 ) 1,309 Total revenues — 29 41,952 2,569 (1,240 ) 43,310 Operating expenses Cost of services, exclusive of depreciation and amortization shown separately below — — 6,257 50 — 6,307 Cost of equipment sales — — 11,238 1,011 (202 ) 12,047 Selling, general and administrative — 11 13,203 985 (1,038 ) 13,161 Depreciation and amortization — — 6,396 90 — 6,486 Gains on disposal of spectrum licenses — — — — — — Total operating expense — 11 37,094 2,136 (1,240 ) 38,001 Operating (loss) income — 18 4,858 433 — 5,309 Other income (expense) Interest expense — (528 ) (114 ) (193 ) — (835 ) Interest expense to affiliates — (522 ) (21 ) — 21 (522 ) Interest income — 23 16 1 (21 ) 19 Other (expense) income, net — (87 ) 33 — — (54 ) Total other (expense) income, net — (1,114 ) (86 ) (192 ) — (1,392 ) Income (loss) before income taxes — (1,096 ) 4,772 241 — 3,917 Income tax expense — — (981 ) (48 ) — (1,029 ) Earnings of subsidiaries 2,888 3,984 32 — (6,904 ) — Net income $ 2,888 $ 2,888 $ 3,823 $ 193 $ (6,904 ) $ 2,888 Dividends on preferred stock — — — — — — Net income attributable to common stockholders $ 2,888 $ 2,888 $ 3,823 $ 193 $ (6,904 ) $ 2,888 Net income $ 2,888 $ 2,888 $ 3,823 $ 193 $ (6,904 ) $ 2,888 Other comprehensive income, net of tax Other comprehensive income, net of tax (332 ) (332 ) 116 — 216 (332 ) Total comprehensive income $ 2,556 $ 2,556 $ 3,939 $ 193 $ (6,688 ) $ 2,556 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 expenses — — 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 income (expense), net — (88 ) 16 (1 ) — (73 ) Total other expense, net 1 (1,430 ) (106 ) (192 ) — (1,727 ) Income (loss) before income taxes 1 (1,427 ) 4,407 180 — 3,161 Income tax 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 Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Revenues Service revenues $ — $ — $ 26,613 $ 2,023 $ (792 ) $ 27,844 Equipment revenues — — 9,145 — (418 ) 8,727 Other revenues — 3 739 195 (18 ) 919 Total revenues — 3 36,497 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 3,826 221 — 4,050 Other income (expense) Interest expense — (1,147 ) (82 ) (189 ) — (1,418 ) Interest expense to affiliates — (312 ) — — — (312 ) Interest income — 31 (18 ) — — 13 Other income (expense), net — 2 (8 ) — — (6 ) Total other expense, net — (1,426 ) (108 ) (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
Schedule of Condensed Consolidating Statement of Cash Flows Information	Condensed Consolidating Statement of Cash Flows Information Year Ended December 31, 2018 (in millions) Parent Issuer Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating and Eliminating Adjustments Consolidated Operating activities Net cash (used in) provided by operating activities $ — $ (1,254 ) $ 10,483 $ (5,110 ) $ (220 ) $ 3,899 Investing activities Purchases of property and equipment — — (5,505 ) (36 ) — (5,541 ) Purchases of spectrum licenses and other intangible assets — — (127 ) — — (127 ) Proceeds related to beneficial interests in securitization transactions — — 53 5,353 — 5,406 Acquisition of companies, net of cash acquired — — (338 ) — — (338 ) Equity investment in subsidiary — — (43 ) — 43 — Other, net — (7 ) 28 — — 21 Net cash (used in) provided by investing activities — (7 ) (5,932 ) 5,317 43 (579 ) Financing activities Proceeds from issuance of long-term debt — 2,494 — — — 2,494 Proceeds from borrowing on revolving credit facility, net — 6,265 — — — 6,265 Repayments of revolving credit facility — — (6,265 ) — — (6,265 ) Repayments of capital lease obligations — — (698 ) (2 ) — (700 ) Repayments of short-term debt for purchases of inventory, property and equipment, net — — (300 ) — — (300 ) Repayments of long-term debt — — (3,349 ) — — (3,349 ) Repurchases of common stock (1,071 ) — — — — (1,071 ) Intercompany advances, net 995 (7,498 ) 6,468 35 — — Equity investment from parent — — — 43 (43 ) — Tax withholdings on share-based awards — — (146 ) — — (146 ) Cash payments for debt prepayment or debt extinguishment costs — — (212 ) — — (212 ) Intercompany dividend paid — — — (220 ) 220 — Other, net 4 — (56 ) — — (52 ) Net cash (used in) provided by financing activities (72 ) 1,261 (4,558 ) (144 ) 177 (3,336 ) Change in cash and cash equivalents (72 ) — (7 ) 63 — (16 ) Cash and cash equivalents Beginning of period 74 1 1,086 58 — 1,219 End of period $ 2 $ 1 $ 1,079 $ 121 $ — $ 1,203 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 ) $ 9,761 $ (4,218 ) $ (100 ) $ 3,831 Investing activities Purchases of property and equipment — — (5,237 ) — — (5,237 ) Purchases of spectrum licenses and other intangible assets — — (5,828 ) — — (5,828 ) Proceeds related to beneficial interests in securitization transactions — — 43 4,276 — 4,319 Equity investment in subsidiary (308 ) — — — 308 — Other, net — — 1 — — 1 Net cash (used in) provided by investing activities (308 ) — (11,021 ) 4,276 308 (6,745 ) 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 ) Repurchases of common stock (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 ) Dividends on preferred stock (55 ) — — — — (55 ) Cash payments for debt prepayment or debt extinguishment costs — — (188 ) — — (188 ) Intercompany dividend paid — — — (100 ) 100 — Other, net 21 — (16 ) — — 5 Net cash provided by (used in) financing activities 23 (1,119 ) 4 (67 ) (208 ) (1,367 ) 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 Balances have been revised based on the guidance in ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments.” See Note 1 – Summary of Significant Accounting Policies for further information. 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 ) $ 7,516 $ (3,298 ) $ (110 ) $ 2,779 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 ) Proceeds related to beneficial interests in securitization transactions — — 25 3,331 — — 3,356 Sales of short-term investments — 2,000 998 — — — 2,998 Other, net — — (8 ) — — (8 ) Net cash provided by (used in) investing activities — 2,000 (7,655 ) 3,331 — (2,324 ) 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 — — Tax withholdings on share-based awards — — (121 ) — — (121 ) Dividends on preferred stock (55 ) — — — — (55 ) Intercompany dividend paid — — — (110 ) 110 — Other, net 29 — (12 ) — — 17 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 Balances have been revised based on the guidance in ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments.” See Note 1 – Summary of Significant Accounting Policies of the Notes to the Consolidated Financial Statements, for further information.

Quarterly Financial Informati_2

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information [Abstract]
Quarterly Financial Information	Quarterly Financial Information (Unaudited) (in millions, except share and per share amounts) First Quarter Second Quarter Third Quarter Fourth Quarter Full Year 2018 Total revenues $ 10,455 $ 10,571 $ 10,839 $ 11,445 $ 43,310 Operating income 1,282 1,450 1,440 1,137 5,309 Net income 671 782 795 640 2,888 Net income attributable to common stockholders 671 782 795 640 2,888 Earnings per share Basic $ 0.78 $ 0.92 $ 0.94 $ 0.75 $ 3.40 Diluted 0.78 0.92 0.93 0.75 3.36 Weighted average shares outstanding Basic 855,222,664 847,660,488 847,087,120 849,102,785 849,744,152 Diluted 862,244,084 852,040,670 853,852,764 856,344,347 858,290,174 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 869,395,984 870,457,181 871,420,065 871,501,578 871,787,450 Net income includes: Gains on disposal of spectrum licenses (37 ) (1 ) (29 ) (168 ) (235 )

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2018USD ($)option	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)unitoption	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Jan. 01, 2019USD ($)	Jan. 01, 2018USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total imputed discount and allowances rate										8.10%	8.10%
Device upgrade period										18 months
Number of upgrade options | option	1									1
Spectrum license issuance period										15 years
Number of reporting units | unit										2
Federal Universal Service Fund and other fees										$ 161,000,000	$ 258,000,000	$ 409,000,000
Advertising expense										1,700,000,000	1,800,000,000	1,700,000,000
Net cash provided by (used in) operating activities										3,899,000,000	3,831,000,000	2,779,000,000
Net cash used in investing activities										(579,000,000)	(6,745,000,000)	(2,324,000,000)
Net cash (used in) provided by financing activities										$ (3,336,000,000)	(1,367,000,000)	463,000,000
Average amortization period, deferred contract costs	24 months									24 months
Revenues	$ 11,445,000,000	$ 10,839,000,000	$ 10,571,000,000	$ 10,455,000,000	$ 10,759,000,000	$ 10,019,000,000	$ 10,213,000,000	$ 9,613,000,000		$ 43,310,000,000	40,604,000,000	37,490,000,000
Interest expense										835,000,000	1,111,000,000	1,418,000,000
Depreciation and amortization										6,486,000,000	5,984,000,000	6,243,000,000
Assets	72,468,000,000				70,563,000,000					72,468,000,000	70,563,000,000
Total operating expense										38,001,000,000	35,716,000,000	33,440,000,000
Net income	$ 640,000,000	$ 795,000,000	$ 782,000,000	$ 671,000,000	$ 2,707,000,000	$ 550,000,000	$ 581,000,000	$ 698,000,000		2,888,000,000	4,536,000,000	1,460,000,000
Other revenues
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues										1,309,000,000	1,069,000,000	919,000,000
Service
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues										31,992,000,000	30,160,000,000	27,844,000,000
Cost of services and equipment sales										6,307,000,000	6,100,000,000	5,731,000,000
Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net income										2,888,000,000	4,536,000,000	1,460,000,000
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment for adoption of new accounting standard														$ 213,000,000
Accounting Standards Update 2014-09 | Contract acquisition costs paid on open contracts
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred contract cost asset														150,000,000
Accounting Standards Update 2014-09 | Contracts with promotional bill credits
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred contract cost asset														140,000,000
Accounting Standards Update 2016-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities										(5,400,000,000)	(4,300,000,000)	(3,400,000,000)
Net cash used in investing activities										5,400,000,000	4,300,000,000	3,400,000,000
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										(212,000,000)	(188,000,000)	$ 0
Net cash (used in) provided by financing activities										$ 212,000,000	$ 188,000,000
Accounting Standards Update 2016-01 | Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment for adoption of new accounting standard														8,000,000
Accounting Standards Update 2016-16 | Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment for adoption of new accounting standard														$ 11,000,000
Accounting Standards Update 2016-02 | Scenario, Forecast
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Average remaining lease term, operating lease													9 years
Accounting Standards Update 2016-02 | Scenario, Forecast | Subsequent Event
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Average remaining lease term for cell sites													4 years
Accounting Standards Update 2016-02 | Scenario, Forecast | Minimum | Subsequent Event | Impact Excluding Failed Sale-Leaseback Transaction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Assets													$ 8,500,000,000
Liabilities													8,200,000,000
Total operating expense									$ 190,000,000
Net income									140,000,000
Accounting Standards Update 2016-02 | Scenario, Forecast | Minimum | Subsequent Event | Impact Including Failed Sale-Leaseback Transaction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities									(20,000,000)
Net cash (used in) provided by financing activities									(20,000,000)
Interest expense									(200,000,000)
Assets													9,100,000,000
Liabilities													7,000,000,000
Total operating expense									220,000,000
Net income									140,000,000
Accounting Standards Update 2016-02 | Scenario, Forecast | Maximum | Subsequent Event | Impact Excluding Failed Sale-Leaseback Transaction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Assets													9,400,000,000
Liabilities													8,900,000,000
Total operating expense									230,000,000
Net income									180,000,000
Accounting Standards Update 2016-02 | Scenario, Forecast | Maximum | Subsequent Event | Impact Including Failed Sale-Leaseback Transaction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities									(40,000,000)
Net cash (used in) provided by financing activities									(40,000,000)
Interest expense									(240,000,000)
Assets													10,000,000,000
Liabilities													7,500,000,000
Total operating expense									260,000,000
Net income									180,000,000
Accounting Standards Update 2016-02 | Scenario, Forecast | Other revenues | Minimum | Subsequent Event | Impact Including Failed Sale-Leaseback Transaction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues									(230,000,000)
Accounting Standards Update 2016-02 | Scenario, Forecast | Other revenues | Maximum | Subsequent Event | Impact Including Failed Sale-Leaseback Transaction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues									$ (250,000,000)
Accounting Standards Update 2016-02 | Accumulated Deficit | Scenario, Forecast | Minimum | Subsequent Event | Impact Excluding Failed Sale-Leaseback Transaction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment for adoption of new accounting standard													(300,000,000)
Accounting Standards Update 2016-02 | Accumulated Deficit | Scenario, Forecast | Minimum | Subsequent Event | Impact Including Failed Sale-Leaseback Transaction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment for adoption of new accounting standard													2,100,000,000
Accounting Standards Update 2016-02 | Accumulated Deficit | Scenario, Forecast | Maximum | Subsequent Event | Impact Excluding Failed Sale-Leaseback Transaction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment for adoption of new accounting standard													(500,000,000)
Accounting Standards Update 2016-02 | Accumulated Deficit | Scenario, Forecast | Maximum | Subsequent Event | Impact Including Failed Sale-Leaseback Transaction
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment for adoption of new accounting standard													$ 2,500,000,000
EIP Securitization Arrangement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equipment installment plan, maximum payment term										36 months

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Cumulative Impact of Adoption (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets
Other current assets	$ 1,676	$ 2,043	$ 1,903
Other assets	1,623	1,062	912
Liabilities and Stockholders' Equity
Deferred revenue	698	783	779
Deferred tax liabilities	4,472	3,610	3,537
Accumulated deficit	(12,954)	(15,861)	$ (16,074)
Accounting Standards Update 2014-09
Liabilities and Stockholders' Equity
Adjustment for adoption of new accounting standard		213
Calculated under Revenue Guidance in Effect before Topic 606
Assets
Other current assets	1,625	1,903
Other assets	979	912
Liabilities and Stockholders' Equity
Deferred revenue	685	779
Deferred tax liabilities	4,297	3,537
Accumulated deficit	(13,461)	(16,074)
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Assets
Other current assets	51	140
Other assets	644	150
Liabilities and Stockholders' Equity
Deferred revenue	13	4
Deferred tax liabilities	175	$ 73
Accumulated deficit	$ 507

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Schedule of Impact of Adoption on Condensed Consolidated Financial Statements (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Revenues
Revenues	$ 11,445	$ 10,839	$ 10,571	$ 10,455	$ 10,759	$ 10,019	$ 10,213	$ 9,613	$ 43,310	$ 40,604	$ 37,490
Operating expenses
Selling, general and administrative									13,161	12,259	11,378
Depreciation and amortization									6,486	5,984	6,243
Total operating expense									38,001	35,716	33,440
Operating income	1,137	1,440	1,450	1,282	1,112	1,323	1,416	1,037	5,309	4,888	4,050
Total other expense, net									(1,392)	(1,727)	(1,723)
Income before income taxes									3,917	3,161	2,327
Income tax expense									(1,029)	1,375	(867)
Net income	$ 640	$ 795	$ 782	$ 671	$ 2,707	$ 550	$ 581	$ 698	$ 2,888	$ 4,536	$ 1,460
Earnings per share
Basic (in USD per share)	$ 0.75	$ 0.94	$ 0.92	$ 0.78	$ 3.22	$ 0.65	$ 0.68	$ 0.83	$ 3.40	$ 5.39	$ 1.71
Diluted (in USD per share)	$ 0.75	$ 0.93	$ 0.92	$ 0.78	$ 3.11	$ 0.63	$ 0.67	$ 0.80	$ 3.36	$ 5.20	$ 1.69
Assets
Other current assets	$ 1,676				$ 1,903				$ 1,676	$ 1,903		$ 2,043
Other assets	1,623				912				1,623	912		1,062
Liabilities and Stockholders' Equity
Deferred revenue	698				779				698	779		783
Deferred tax liabilities	4,472				3,537				4,472	3,537		3,610
Accumulated deficit	(12,954)				$ (16,074)				(12,954)	(16,074)		(15,861)
Branded postpaid revenues
Revenues
Revenues									20,862	19,448	$ 18,138
Branded prepaid revenues
Revenues
Revenues									9,598	9,380	8,553
Wholesale revenues
Revenues
Revenues									1,183	1,102	903
Roaming and other service revenues
Revenues
Revenues									349	230	250
Service
Revenues
Revenues									31,992	30,160	27,844
Operating expenses
Cost of services and equipment sales									6,307	6,100	5,731
Product
Revenues
Revenues									10,009	9,375	8,727
Operating expenses
Cost of services and equipment sales									12,047	11,608	10,819
Other revenues
Revenues
Revenues									1,309	$ 1,069	$ 919
Calculated under Revenue Guidance in Effect before Topic 606
Revenues
Revenues									42,952
Operating expenses
Selling, general and administrative									13,257
Depreciation and amortization									6,486
Total operating expense									38,041
Operating income									4,911
Total other expense, net									(1,392)
Income before income taxes									3,519
Income tax expense									(926)
Net income									$ 2,593
Earnings per share
Basic (in USD per share)									$ 3.05
Diluted (in USD per share)									$ 3.02
Assets
Other current assets	1,625								$ 1,625			1,903
Other assets	979								979			912
Liabilities and Stockholders' Equity
Deferred revenue	685								685			779
Deferred tax liabilities	4,297								4,297			3,537
Accumulated deficit	(13,461)								(13,461)			(16,074)
Calculated under Revenue Guidance in Effect before Topic 606 | Branded postpaid revenues
Revenues
Revenues									20,887
Calculated under Revenue Guidance in Effect before Topic 606 | Branded prepaid revenues
Revenues
Revenues									9,608
Calculated under Revenue Guidance in Effect before Topic 606 | Wholesale revenues
Revenues
Revenues									1,183
Calculated under Revenue Guidance in Effect before Topic 606 | Roaming and other service revenues
Revenues
Revenues									349
Calculated under Revenue Guidance in Effect before Topic 606 | Service
Revenues
Revenues									32,027
Operating expenses
Cost of services and equipment sales									6,233
Calculated under Revenue Guidance in Effect before Topic 606 | Product
Revenues
Revenues									9,616
Operating expenses
Cost of services and equipment sales									12,065
Calculated under Revenue Guidance in Effect before Topic 606 | Other revenues
Revenues
Revenues									1,309
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Revenues
Revenues									358
Operating expenses
Selling, general and administrative									(96)
Depreciation and amortization									0
Total operating expense									(40)
Operating income									398
Total other expense, net									0
Income before income taxes									398
Income tax expense									(103)
Net income									$ 295
Earnings per share
Basic (in USD per share)									$ 0.35
Diluted (in USD per share)									$ 0.34
Assets
Other current assets	51								$ 51			140
Other assets	644								644			150
Liabilities and Stockholders' Equity
Deferred revenue	13								13			4
Deferred tax liabilities	175								175			$ 73
Accumulated deficit	$ 507								507
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Branded postpaid revenues
Revenues
Revenues									(25)
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Branded prepaid revenues
Revenues
Revenues									(10)
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Wholesale revenues
Revenues
Revenues									0
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Roaming and other service revenues
Revenues
Revenues									0
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Service
Revenues
Revenues									(35)
Operating expenses
Cost of services and equipment sales									74
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Product
Revenues
Revenues									393
Operating expenses
Cost of services and equipment sales									(18)
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Other revenues
Revenues
Revenues									$ 0

Business Combinations - Narrati

Business Combinations - Narrative (Details) - USD ($)	May 18, 2018	Apr. 29, 2018	Jan. 22, 2018	Jan. 01, 2018	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017
Business Acquisition [Line Items]
Payments for third party bank fees							$ 13,161,000,000	$ 12,259,000,000	$ 11,378,000,000
Costs recognized associated with merger transaction									$ 104,000,000
Goodwill					$ 1,901,000,000		$ 1,901,000,000	$ 1,683,000,000
Sprint
Business Acquisition [Line Items]
Exchange ratio		0.10256
Exchange ratio (in shares)		9.75000
Fully-diluted shares of combined company held by public stockholders (percent)					30.90%		30.90%
Payments of consent fees							$ 31,000,000
Accrued required reimbursement by acquiree upon termination					$ 0		0
Required reimbursement by acquiree upon termination, percentage	33.00%
Upfront payments to third party note holders by acquiree							241,000,000
Required reimbursement by acquirer upon termination, percentage	67.00%
Required reimbursement by acquirer upon termination	$ 161,000,000
Accrued required reimbursement by acquirer upon termination					0		0
Costs recognized associated with merger transaction							196,000,000
Required payment resulting from failure to satisfy closing condition of business combination agreement (up to)		$ 600,000,000
Sprint | Senior Notes
Business Acquisition [Line Items]
Payments of consent fees	$ 14,000,000				54,000,000	$ 17,000,000
Payments for third party bank fees						6,000,000	$ 6,000,000
Sprint | Deutsche Telekom AG
Business Acquisition [Line Items]
Payments of consent fees					$ 20,000,000	$ 7,000,000
Sprint | Deutsche Telekom AG
Business Acquisition [Line Items]
Fully-diluted shares expected to be held immediately following merger (percent)					41.70%		41.70%
Sprint | SoftBank
Business Acquisition [Line Items]
Fully-diluted shares expected to be held immediately following merger (percent)					27.40%		27.40%
Layer3 TV
Business Acquisition [Line Items]
Cash consideration			$ 318,000,000
Payment included in consideration after closing of transaction			5,000,000
Grant-date fair value of cash-based and share-based incentive compensation awards			37,000,000
Liability recognized			21,000,000
Indemnification assets			12,000,000
Goodwill			218,000,000
Intangible assets			$ 100,000,000
Layer3 TV | Developed Technology
Business Acquisition [Line Items]
Estimated useful life (in years)			5 years
Iowa Wireless
Business Acquisition [Line Items]
Cash consideration				$ 25,000,000
Purchase price of unconsolidated subsidiary				25,000,000
Fair value of equity interest held				56,000,000
Gain on remeasurement of equity interest				15,000,000
Bargain purchase gain				$ 25,000,000
Unconsolidated subsidiary ownership percentage				54.00%						54.00%

Business Combinations - Schedul

Business Combinations - Schedule of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jan. 22, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets acquired
Goodwill	$ 1,901			$ 1,683
Layer3 TV
Assets acquired
Cash and cash equivalents		$ 2
Other current assets		14
Property and equipment, net		11
Intangible assets		100
Goodwill		218
Deferred tax assets		2
Total assets acquired		347
Liabilities assumed
Accounts payable and accrued liabilities		27
Short-term debt		2
Total liabilities assumed		29
Total consideration transferred		$ 318
Iowa Wireless
Assets acquired
Cash and cash equivalents			$ 3
Accounts receivable, net			6
Equipment installment plan receivables, net			3
Inventories			1
Other current assets			2
Current assets, total			15
Property and equipment, net			36
Spectrum licenses	$ 87		87
Total assets acquired			138
Liabilities assumed
Accounts payable and accrued liabilities			6
Deferred revenue			2
Current liabilities, total			8
Deferred tax liabilities			17
Other long-term liabilities			7
Total long-term liabilities			24
Total consideration transferred			$ 106

Business Combinations - Conside

Business Combinations - Consideration Transferred - Iowa Wireless (Details) - Iowa Wireless $ in Millions	Jan. 01, 2018USD ($)
Business Acquisition [Line Items]
Cash paid	$ 25
Acquisition date fair value of previously held equity interest	56
Bargain purchase gain	25
Net assets acquired	$ 106

Receivables and Allowance for_3

Receivables and Allowance for Credit Losses - EIP Receivables (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)segmentclass	Dec. 31, 2017USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Portfolio segments | segment	2
Customer classes | class	2
EIP receivables, gross	$ 4,534	$ 3,960
Unamortized imputed discount	(330)	(264)
EIP receivables, net of unamortized imputed discount	4,204	3,696
Allowance for credit losses	(119)	(132)
Equipment installment plan receivables, net	4,085	3,564
Equipment installment plan receivables, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Equipment installment plan receivables, net	2,538	2,290
Equipment installment plan receivables due after one year, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Equipment installment plan receivables, net	$ 1,547	$ 1,274

Receivables and Allowance for_4

Receivables and Allowance for Credit Losses - Unamortized Imputed Discount and Allowance for Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses and imputed discount, beginning of period	$ 482	$ 418	$ 449
Bad debt expense	297	388	477
Write-offs, net of recoveries	(328)	(393)	(518)
Change in imputed discount on short-term and long-term EIP receivables	250	252	186
Impact on the imputed discount from sales of EIP receivables	(185)	(183)	(176)
Allowance for credit losses and imputed discount, end of period	516	482	418
Accounts Receivable Allowance
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses and imputed discount, beginning of period	86	102	116
Bad debt expense	69	104	227
Write-offs, net of recoveries	(88)	(120)	(241)
Allowance for credit losses and imputed discount, end of period	$ 67	$ 86	$ 102
EIP Receivables Allowance
Financing Receivable, Allowance for Credit Losses [Line Items]
Weighted average effective imputed interest rate	10.00%	9.60%	9.00%
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses and imputed discount, beginning of period	$ 396	$ 316	$ 333
Bad debt expense	228	284	250
Write-offs, net of recoveries	(240)	(273)	(277)
Change in imputed discount on short-term and long-term EIP receivables	250	252	186
Impact on the imputed discount from sales of EIP receivables	(185)	(183)	(176)
Allowance for credit losses and imputed discount, end of period	$ 449	$ 396	$ 316

Receivables and Allowance for_5

Receivables and Allowance for Credit Losses - Gross EIP Receivables by Credit Category (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	$ 4,534	$ 3,960
Prime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	2,015	1,758
Subprime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	2,519	2,202
Current - 30 days past due
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	4,433	3,860
Current - 30 days past due | Prime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	1,987	1,727
Current - 30 days past due | Subprime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	2,446	2,133
31 - 60 days past due
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	47	46
31 - 60 days past due | Prime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	15	17
31 - 60 days past due | Subprime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	32	29
61 - 90 days past due
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	25	22
61 - 90 days past due | Prime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	6	6
61 - 90 days past due | Subprime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	19	16
More than 90 days past due
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	29	32
More than 90 days past due | Prime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	7	8
More than 90 days past due | Subprime
Financing Receivable, Recorded Investment [Line Items]
EIP receivables, gross	$ 22	$ 24

Sales of Certain Receivables -

Sales of Certain Receivables - Sales of Service Receivables (Details) - USD ($)	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Nov. 30, 2016
Variable Interest Entity [Line Items]
Other current assets	$ 1,676,000,000	$ 2,043,000,000	$ 1,903,000,000
Accounts payable and accrued liabilities	7,741,000,000		8,528,000,000
Other current liabilities	787,000,000		414,000,000
Factoring Arrangement | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Revolving receivables facility, maximum borrowing capacity				$ 950,000,000
Revolving receivables facility, outstanding borrowings	774,000,000		880,000,000
Other current assets	339,000,000		236,000,000
Accounts payable and accrued liabilities	59,000,000		25,000,000
Other current liabilities	$ 149,000,000		$ 180,000,000

Sales of Certain Receivables _2

Sales of Certain Receivables - Sales of EIP Receivables (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Aug. 31, 2017
Variable Interest Entity [Line Items]
Other current assets	$ 1,676,000,000	$ 2,043,000,000	$ 1,903,000,000
Other assets	1,623,000,000	$ 1,062,000,000	912,000,000
EIP Securitization Arrangement
Variable Interest Entity [Line Items]
Revolving receivables facility, maximum borrowing capacity			1,300,000,000	$ 1,200,000,000
Revolving receivables facility, outstanding borrowings	$ 1,300,000,000		1,300,000,000
Equipment installment plan, maximum payment term	36 months
Other current assets	$ 321,000,000		403,000,000
Other assets	88,000,000		109,000,000
Other long-term liabilities	$ 22,000,000		$ 3,000,000

Sales of Certain Receivables _3

Sales of Certain Receivables - Sales of Receivables and Continuing Involvement (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]
Other current assets	$ 1,676	$ 1,903		$ 2,043
Other long-term assets	1,623	912		$ 1,062
Accounts payable and accrued liabilities	7,741	8,528
Other current liabilities	787	414
Other long-term liabilities	967	935
Of which:
Losses from sales of receivables	157	299	$ 228
Factoring and EIP Securitization Arrangement | Variable Interest Entity, Primary Beneficiary
Of which:
Maximum exposure to loss, Factoring VIE	1,200
Factoring and EIP Securitization Arrangement
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]
Derecognized net service receivables and EIP receivables	2,577	2,725
Other current assets	660	639
Deferred purchase price assets	746	745
Other long-term assets	88	109
Accounts payable and accrued liabilities	59	25
Other current liabilities	149	180
Other long-term liabilities	22	3
Net cash proceeds since inception	1,879	2,058
Of which:
Change in net cash proceeds during the year-to-date period	(179)	28
Net cash proceeds funded by reinvested collections	2,058	2,030
Losses from sales of receivables	157	299	$ 228
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	658	636
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	$ 88	$ 109

Property and Equipment (Detail

Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ (31,297)	$ (27,301)
Property and equipment, net	23,359	22,196
Capital leased assets, gross	3,100	2,400
Capital leased assets, accumulated amortization	867	533
Capitalized interest	362	136	$ 142
Buildings and equipment
Property, Plant and Equipment [Line Items]
Property and equipment	2,423	2,066
Wireless communications systems
Property, Plant and Equipment [Line Items]
Property and equipment	35,282	32,706
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	1,299	1,182
Capitalized software
Property, Plant and Equipment [Line Items]
Property and equipment	11,712	10,563
Leased devices
Property, Plant and Equipment [Line Items]
Property and equipment	1,164	1,209
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment	$ 2,776	$ 1,771
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 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, 2018	Dec. 31, 2017	Dec. 31, 2016
Property Subject to or Available for Operating Lease, Net [Abstract]
Leased wireless devices, gross	$ 1,159	$ 1,209
Accumulated depreciation	(622)	(417)
Leased wireless devices, net	537	792
Operating Leases, Future Minimum Payments Receivable [Abstract]
2,019	419
2,020	59
Total	478
Depreciation expense	6,400	5,800	$ 6,000
Depreciation expense for lease devices	940	1,000	1,500
Additional depreciation expense	$ 60	$ 63	$ 101

Property and Equipment - Asset

Property and Equipment - Asset Retirement Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations, beginning of year	$ 562	$ 539
Liabilities incurred	26	25
Liabilities settled	(9)	(16)
Accretion expense	30	27
Changes in estimated cash flows	0	(13)
Asset retirement obligations, end of year	609	562
Asset retirement costs capitalized, net	194	220
Other current liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations, beginning of year	3
Asset retirement obligations, end of year	0	3
Other long-term liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations, beginning of year	559
Asset retirement obligations, end of year	$ 609	$ 559

Goodwill, Spectrum License Tr_3

Goodwill, Spectrum License Transactions and Other Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Historical goodwill		$ 12,449
Accumulated impairment losses	$ (10,766)	$ (10,766)
December 31, 2017	1,683
Goodwill from acquisition of Layer3 TV	218
December 31, 2018	$ 1,901

Goodwill, Spectrum License Tr_4

Goodwill, Spectrum License Transactions and Other Intangible Assets - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jan. 22, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill	$ 1,901		$ 1,683
Layer3 TV
Goodwill [Line Items]
Goodwill		$ 218

Goodwill, Spectrum License Tr_5

Goodwill, Spectrum License Transactions and Other Intangible Assets - Spectrum Licenses (Details) $ in Millions	Jan. 01, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	May 31, 2017USD ($)	Apr. 30, 2017USD ($)license	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Jun. 30, 2016USD ($)
Indefinite-lived Intangible Assets [Roll Forward]
Purchase of spectrum licenses											$ 127	$ 5,828	$ 3,968
Gains or losses recognized on spectrum license purchase							$ 168	$ 29	$ 1	$ 37	0	235	835
Number of licenses | license					1,525
Iowa Wireless
Indefinite-lived Intangible Assets [Roll Forward]
Spectrum licenses	$ 87										87
Unconsolidated subsidiary ownership percentage	54.00%		54.00%					54.00%
Purchase price of unconsolidated subsidiary	$ 25
Licensing Agreements
Indefinite-lived Intangible Assets [Roll Forward]
Beginning balance	$ 35,366									$ 27,014	35,366	27,014
Spectrum license acquisitions											138	8,599
Spectrum licenses transferred to held for sale											(1)	(271)
Costs to clear spectrum											56	24
Ending balance		$ 35,366					$ 35,366				35,559	$ 35,366	$ 27,014
Purchase of spectrum licenses					$ 8,000						$ 50
Gains or losses recognized on spectrum license purchase		168	$ 29			$ 37
Asset purchase deposit														$ 2,200
Remaining purchase price				$ 5,800
Licensing Agreements | Fair Value
Indefinite-lived Intangible Assets [Roll Forward]
Spectrum license acquisitions		$ 352	$ 115			$ 123

Goodwill, Spectrum License Tr_6

Goodwill, Spectrum License Transactions and Other Intangible Assets - Other Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 0	$ 0
Indefinite-lived intangible asset impairment	0	0
Gross Amount	1,565,000,000	1,460,000,000
Accumulated Amortization	(1,367,000,000)	(1,243,000,000)
Net Amount	198,000,000	217,000,000
Amortization expense for intangible assets	124,000,000	163,000,000	$ 220,000,000
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
2,019	73,000,000
2,020	55,000,000
2,021	35,000,000
2,022	25,000,000
2,023	6,000,000
Thereafter	4,000,000
Net Amount	198,000,000	217,000,000
Customer lists
Finite-Lived Intangible Assets [Line Items]
Gross Amount	1,104,000,000	1,104,000,000
Accumulated Amortization	(1,086,000,000)	(1,016,000,000)
Net Amount	18,000,000	88,000,000
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Net Amount	$ 18,000,000	88,000,000
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	$ 312,000,000	307,000,000
Accumulated Amortization	(225,000,000)	(192,000,000)
Net Amount	87,000,000	115,000,000
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Net Amount	$ 87,000,000	115,000,000
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	$ 149,000,000	49,000,000
Accumulated Amortization	(56,000,000)	(35,000,000)
Net Amount	93,000,000	14,000,000
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Net Amount	$ 93,000,000	$ 14,000,000
Other | Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life (in years)	28 years

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2018
Derivative [Line Items]
Change in fair value of interest rate lock derivatives	$ 332
Fair value of embedded derivative instruments	19	$ 66
Gain activity related to embedded derivative instruments	29	52	$ 25
Guarantee liabilities	73	105
EIP receivables, gross	4,534	$ 3,960
Equipment installment plan receivables, net
Derivative [Line Items]
EIP receivables, gross	3,000
Interest Rate Contract
Derivative [Line Items]
Change in fair value of interest rate lock derivatives	332
Cash Flow Hedging | Interest Rate Contract
Derivative [Line Items]
Aggregate notional amount				$ 9,600
Fair value of derivative instrument	$ 447

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Short-term Investments and Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Level 1 | Reported Value Measurement | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 10,950	$ 11,910
Level 1 | Fair Value | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	10,945	12,540
Level 2 | Reported Value Measurement | Secured Term Loan [$4.0B]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Term loans	4,000	4,000
Level 2 | Reported Value Measurement | Affiliated Entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	598	3,100
Level 2 | Reported Value Measurement | Senior Notes | Affiliated Entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	9,984	7,486
Level 2 | Fair Value | Secured Term Loan [$4.0B]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Term loans	3,976	4,020
Level 2 | Fair Value | Affiliated Entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	640	3,260
Level 2 | Fair Value | Senior Notes | Affiliated Entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	9,802	7,852
Level 3 | Reported Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred purchase price assets	746	745
Level 3 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred purchase price assets	$ 746	$ 745

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jan. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Capital leases	$ 2,015		$ 1,824
Premium	0		78
Debt issuance costs and consent fees	(56)		(19)
Total debt	27,547		28,319
Less: Current portion of capital leases	841		613
Total long-term debt	26,706		26,707
Long-term debt	12,124		12,121
Long-term debt to affiliates	14,582		14,586
Senior Notes
Debt Instrument [Line Items]
Less: Current portion of Senior Notes	0		999
Affiliated Entity
Debt Instrument [Line Items]
Premium	52		59
Discount	(64)		(73)
Long-term debt to affiliates	14,582		$ 14,586
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	$ 0		$ 1,250
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		$ 2,000
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	$ 0		$ 1,250
4.000% Senior Notes due 2022
Debt Instrument [Line Items]
Interest rate, stated percentage	4.00%
Senior notes	$ 500		500
4.000% Senior Notes due 2022 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	4.00%
Senior notes to affiliates	$ 1,000		$ 1,000
6.125% Senior Notes due 2022
Debt Instrument [Line Items]
Interest rate, stated percentage			6.125%
Senior notes	$ 0		$ 1,000
6.125% Senior Notes due 2022 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	6.125%	6.125%
Incremental term loan facility to affiliates due 2022 | Affiliated Entity
Debt Instrument [Line Items]
Senior notes to affiliates	$ 2,000		2,000
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	$ 0		$ 1,750
6.625% Senior Notes due 2023 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	6.625%
6.836% Senior Notes due 2023
Debt Instrument [Line Items]
Interest rate, stated percentage			6.836%
Senior notes	$ 0		$ 600
6.836% Senior Notes due 2023 | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	6.836%
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 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	6.00%
Senior notes to affiliates	$ 1,350		1,350
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		650
Incremental term loan facility to affiliates due 2024 | Affiliated Entity
Debt Instrument [Line Items]
Senior notes to affiliates	$ 2,000		2,000
5.125% Senior Notes Due 2025
Debt Instrument [Line Items]
Interest rate, stated percentage	5.125%
Senior notes	$ 500		500
5.125% Senior Notes Due 2025 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	5.125%
Senior notes to affiliates	$ 1,250		1,250
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	6.50%
Senior notes	$ 2,000		2,000
4.500% Senior Notes due 2026
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%
Senior notes	$ 1,000		0
4.500% Senior Notes due 2026 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%
Senior notes to affiliates	$ 1,000		0
5.375% Senior Notes Due 2027
Debt Instrument [Line Items]
Interest rate, stated percentage	5.375%
Senior notes	$ 500		500
5.375% Senior Notes Due 2027 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	5.375%
Senior notes to affiliates	$ 1,250		1,250
4.750% Senior Notes due 2028
Debt Instrument [Line Items]
Interest rate, stated percentage	4.75%
Senior notes	$ 1,500		0
4.750% Senior Notes due 2028 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage	4.75%
Senior notes to affiliates	$ 1,500		$ 0

Debt - Debt to Third Parties -

Debt - Debt to Third Parties - Issuances and Borrowings (Details) - USD ($)	Apr. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 30, 2018	Apr. 28, 2018
Debt Instrument [Line Items]
Principal Issuances		$ 2,500,000,000
Issuance Costs		6,000,000
Net Proceeds from Issuance of Long-Term Debt		2,494,000,000
Proceeds from issuance of long-term debt		2,494,000,000	$ 10,480,000,000	$ 997,000,000
4.500% Senior Notes due 2026
Debt Instrument [Line Items]
Principal Issuances		1,000,000,000
Issuance Costs		2,000,000
Net Proceeds from Issuance of Long-Term Debt		$ 998,000,000
Interest rate, stated percentage		4.50%
4.500% Senior Notes due 2026 | Issuer
Debt Instrument [Line Items]
Interest rate, stated percentage					4.50%
4.750% Senior Notes due 2028
Debt Instrument [Line Items]
Principal Issuances		$ 1,500,000,000
Issuance Costs		4,000,000
Net Proceeds from Issuance of Long-Term Debt		$ 1,496,000,000
Interest rate, stated percentage		4.75%
4.750% Senior Notes due 2028 | Issuer
Debt Instrument [Line Items]
Interest rate, stated percentage					4.75%
4.500% Senior Notes due 2026 and 4.750% Senior Notes due 2028 | Issuer
Debt Instrument [Line Items]
Proceeds from issuance of long-term debt	$ 2,494,000,000
6.625% Senior Notes due 2023
Debt Instrument [Line Items]
Interest rate, stated percentage			6.625%
6.625% Senior Notes due 2023 | Issuer
Debt Instrument [Line Items]
Principal Issuances	$ 1,750,000,000
Interest rate, stated percentage	6.625%
6.836% Senior Notes due 2023
Debt Instrument [Line Items]
Interest rate, stated percentage			6.836%
6.836% Senior Notes due 2023 | Issuer
Debt Instrument [Line Items]
Principal Issuances						$ 600,000,000
Interest rate, stated percentage						6.836%

Debt - Debt to Third Parties _2

Debt - Debt to Third Parties - Notes Redemption (Details) - USD ($)	Apr. 28, 2018	Apr. 01, 2018	Jan. 15, 2018	Dec. 31, 2018	Jan. 31, 2018	Dec. 31, 2017
6.125% Senior Notes due 2022
Debt Instrument [Line Items]
Redemption price (as a percent)			103.063%
Interest rate, stated percentage						6.125%
6.625% Senior Notes due 2023
Debt Instrument [Line Items]
Redemption price (as a percent)		103.313%
Interest rate, stated percentage						6.625%
6.836% Senior Notes due 2023
Debt Instrument [Line Items]
Redemption price (as a percent)	103.418%
Interest rate, stated percentage						6.836%
Senior Notes | 6.125% Senior Notes due 2022
Debt Instrument [Line Items]
Principal Amount				$ 1,000,000,000	$ 1,000,000,000
Write-off of Premiums, Discounts and Issuance Costs				1,000,000
Call Penalties				$ 31,000,000
Interest rate, stated percentage				6.125%	6.125%
Senior Notes | 6.625% Senior Notes due 2023
Debt Instrument [Line Items]
Principal Amount				$ 1,750,000,000
Write-off of Premiums, Discounts and Issuance Costs				(75,000,000)
Call Penalties				$ 58,000,000
Interest rate, stated percentage				6.625%
Senior Notes | 6.836% Senior Notes due 2023
Debt Instrument [Line Items]
Principal Amount				$ 600,000,000
Write-off of Premiums, Discounts and Issuance Costs				0
Call Penalties				$ 21,000,000
Interest rate, stated percentage				6.836%

Debt - Debt to Affiliates - Iss

Debt - Debt to Affiliates - Issuances and Borrowings (Details) - USD ($)	Apr. 30, 2018	Apr. 28, 2018	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Principal Issuances			$ 2,500,000,000
4.500% Senior Notes due 2026
Debt Instrument [Line Items]
Principal Issuances			$ 1,000,000,000
Interest rate, stated percentage			4.50%
4.500% Senior Notes due 2026 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage			4.50%
4.750% Senior Notes due 2028
Debt Instrument [Line Items]
Principal Issuances			$ 1,500,000,000
Interest rate, stated percentage			4.75%
4.750% Senior Notes due 2028 | Affiliated Entity
Debt Instrument [Line Items]
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%
8.195% Senior Reset Notes to affiliates due 2022 | Affiliated Entity
Debt Instrument [Line Items]
Interest rate, stated percentage				8.195%
Senior Notes | Affiliated Entity | Deutsche Telekom AG
Debt Instrument [Line Items]
Principal Issuances	$ 2,500,000,000
Senior Reset Notes | Affiliated Entity | Deutsche Telekom AG
Debt Instrument [Line Items]
Principal Issuances	2,500,000,000
Write-off of Embedded Derivatives	(16,000,000)
Other	102,000,000
Senior Reset Notes | 8.097% Senior Reset Notes to affiliates due 2021
Debt Instrument [Line Items]
Interest rate, stated percentage			8.097%
Senior Reset Notes | 8.097% Senior Reset Notes to affiliates due 2021 | Affiliated Entity | Deutsche Telekom AG
Debt Instrument [Line Items]
Principal Issuances	1,250,000,000
Write-off of Embedded Derivatives	(8,000,000)
Other	51,000,000
Redemption price (as a percent)		104.0485%
Senior Reset Notes | 8.195% Senior Reset Notes to affiliates due 2022
Debt Instrument [Line Items]
Interest rate, stated percentage			8.195%
Senior Reset Notes | 8.195% Senior Reset Notes to affiliates due 2022 | Affiliated Entity | Deutsche Telekom AG
Debt Instrument [Line Items]
Principal Issuances	1,250,000,000
Write-off of Embedded Derivatives	(8,000,000)
Other	$ 51,000,000
Redemption price (as a percent)		104.0975%
Issuer | 4.500% Senior Notes due 2026
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%
Issuer | 4.500% Senior Notes due 2026 | Affiliated Entity | Deutsche Telekom AG
Debt Instrument [Line Items]
Principal Issuances	$ 1,000,000,000
Issuer | 4.750% Senior Notes due 2028
Debt Instrument [Line Items]
Interest rate, stated percentage	4.75%
Issuer | 4.750% Senior Notes due 2028 | Affiliated Entity | Deutsche Telekom AG
Debt Instrument [Line Items]
Principal Issuances	$ 1,500,000,000

Debt - Debt to Affiliates - Inc

Debt - Debt to Affiliates - Incremental Term Loan Facility (Details) - USD ($)	1 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Short-term Debt [Line Items]
Issuance Costs		$ 6,000,000
Deutsche Telekom AG | Affiliated Entity
Short-term Debt [Line Items]
Soft-call prepayment premium (percent)	1.00%
Issuance Costs		$ 0	$ 0
Deutsche Telekom AG | LIBOR plus 1.50% Senior Secured Term Loan due 2022 | Affiliated Entity
Short-term Debt [Line Items]
Applicable margin, percentage	1.50%
Senior Secured Term Loans	$ 2,000,000,000
Deutsche Telekom AG | LIBOR plus 1.75% Senior Secured Term Loan due 2024 | Affiliated Entity
Short-term Debt [Line Items]
Applicable margin, percentage	1.75%
Senior Secured Term Loans	$ 2,000,000,000

Debt - Debt to Affiliates - Rev

Debt - Debt to Affiliates - Revolving Credit Facility (Details) - USD ($)	1 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Jan. 31, 2018	Dec. 31, 2017
Revolving Credit Facility [$2.5B] | Affiliated Entity | Unsecured Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Applicable margin, percentage	2.05%
Undrawn commitment fee, percentage	0.20%
Revolving Credit Facility [$2.5B] | Affiliated Entity | Unsecured Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Applicable margin, percentage	3.05%
Undrawn commitment fee, percentage	0.575%
Revolving Credit Facility [$2.5B] | Affiliated Entity | Secured Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Applicable margin, percentage	1.05%
Undrawn commitment fee, percentage	0.25%
Revolving Credit Facility [$2.5B] | Affiliated Entity | Secured Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Applicable margin, percentage	1.80%
Undrawn commitment fee, percentage	0.45%
Revolving Credit Facility [$2.5B] | Line of Credit | Affiliated Entity | Secured Revolving Credit Facility | Deutsche Telekom AG
Debt Instrument [Line Items]
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
Debt Instrument [Line Items]
Principal Amount		$ 1,000,000,000	$ 1,000,000,000
Interest rate, stated percentage		6.125%	6.125%

Debt - Debt to Affiliates - Com

Debt - Debt to Affiliates - Commitment Letter (Details) - Sprint - USD ($)	Apr. 29, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Payments of consent fees		$ 31,000,000
Secured and Unsecured Debt Financing
Debt Instrument [Line Items]
Financing commitment, amount		30,000,000,000
Secured and Unsecured Debt Financing | Scenario, Forecast | Scenario One
Debt Instrument [Line Items]
Payments of consent fees	$ 340,000,000
Secured Revolving Credit Facility
Debt Instrument [Line Items]
Financing commitment, amount		4,000,000,000
Secured Term Loan Facility
Debt Instrument [Line Items]
Financing commitment, amount		7,000,000,000
Secured Bridge Loan Facility
Debt Instrument [Line Items]
Financing commitment, amount		$ 19,000,000,000

Debt - Debt to Affiliates - Fin

Debt - Debt to Affiliates - Financing Matters Agreement and Consents on Debt to Third-Parties (Details) - USD ($)	May 18, 2018	Apr. 29, 2018	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Principal Issuances			$ 2,500,000,000		$ 2,500,000,000
Payments for third party bank fees					$ 13,161,000,000	$ 12,259,000,000	$ 11,378,000,000
5.125% Senior Notes Due 2025
Debt Instrument [Line Items]
Interest rate, stated percentage			5.125%		5.125%
5.375% Senior Notes Due 2027
Debt Instrument [Line Items]
Interest rate, stated percentage			5.375%		5.375%
Sprint
Debt Instrument [Line Items]
Payments of consent fees					$ 31,000,000
Notes issued and outstanding under Existing Sprint Spectrum Program (not exceed)	$ 7,000,000,000
Sprint | Credit Facilities
Debt Instrument [Line Items]
Financing commitment, amount	$ 9,000,000,000
Secured indebtedness, limit, percentage	150.00%
Secured debt to cash flow	2
Sprint | Senior Notes
Debt Instrument [Line Items]
Payments of consent fees	$ 14,000,000		$ 54,000,000	$ 17,000,000
Payments for third party bank fees				6,000,000	$ 6,000,000
Sprint | Senior Notes | Existing Sprint Spectrum Notes
Debt Instrument [Line Items]
Payments of consent fees			41,000,000	14,000,000
Sprint | Deutsche Telekom AG
Debt Instrument [Line Items]
Payments of consent fees			$ 20,000,000	$ 7,000,000
Sprint | Deutsche Telekom AG | Senior Notes | 5.300% Senior Notes to affiliates due 2021
Debt Instrument [Line Items]
Repayment of debt		$ 2,000,000,000
Interest rate, stated percentage		5.30%
Sprint | Deutsche Telekom AG | Senior Notes | 6.000% Senior Notes due 2024
Debt Instrument [Line Items]
Repayment of debt		$ 2,000,000,000
Interest rate, stated percentage		6.00%
Sprint | Deutsche Telekom AG | Senior Notes | 5.125% Senior Notes Due 2025
Debt Instrument [Line Items]
Interest rate, stated percentage		5.125%
Principal Issuances		$ 1,250,000,000
Sprint | Deutsche Telekom AG | Senior Notes | 5.375% Senior Notes Due 2027
Debt Instrument [Line Items]
Interest rate, stated percentage		5.375%
Principal Issuances		$ 1,250,000,000

Debt - Financing Arrangements a

Debt - Financing Arrangements and Revolving Credit Facility (Details) - USD ($)	1 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 31, 2018
Debt Instrument [Line Items]
Repayments		$ 300,000,000	$ 300,000,000	$ 150,000,000
Revolving Credit Facility [$2.5B] | Affiliated Entity
Debt Instrument [Line Items]
Revolving credit facility		2,500,000,000
Revolving Credit Facility [$2.5B] | Unsecured Revolving Credit Facility | Affiliated Entity
Debt Instrument [Line Items]
Revolving credit facility		1,000,000,000
Revolving Credit Facility [$2.5B] | Unsecured Revolving Credit Facility | Affiliated Entity | Minimum
Debt Instrument [Line Items]
Applicable margin, percentage	2.05%
Undrawn commitment fee, percentage	0.20%
Revolving Credit Facility [$2.5B] | Unsecured Revolving Credit Facility | Affiliated Entity | Maximum
Debt Instrument [Line Items]
Applicable margin, percentage	3.05%
Undrawn commitment fee, percentage	0.575%
Revolving Credit Facility [$2.5B] | Secured Revolving Credit Facility | Affiliated Entity | Minimum
Debt Instrument [Line Items]
Applicable margin, percentage	1.05%
Undrawn commitment fee, percentage	0.25%
Revolving Credit Facility [$2.5B] | Secured Revolving Credit Facility | Affiliated Entity | Maximum
Debt Instrument [Line Items]
Applicable margin, percentage	1.80%
Undrawn commitment fee, percentage	0.45%
6.125% Senior Notes due 2022
Debt Instrument [Line Items]
Interest rate, stated percentage			6.125%
Line of Credit | Revolving Credit Facility [$2.5B] | Secured Revolving Credit Facility | Affiliated Entity | Deutsche Telekom AG
Debt Instrument [Line Items]
Outstanding borrowings		0	$ 0
Line of Credit | Revolving Credit Facility [$1.5B] | Secured Revolving Credit Facility | Affiliated Entity | Deutsche Telekom AG
Debt Instrument [Line Items]
Financing commitment, amount		1,500,000,000
Senior Notes | 6.125% Senior Notes due 2022
Debt Instrument [Line Items]
Principal Amount		$ 1,000,000,000			$ 1,000,000,000
Interest rate, stated percentage		6.125%			6.125%
Handset Financing Arrangement
Debt Instrument [Line Items]
Borrowing capacity		$ 108,000,000
Repayments			100,000,000
Outstanding balance		0	0
Vendor Financing Arrangement
Debt Instrument [Line Items]
Repayments		300,000,000
Outstanding balance		$ 0	$ 0

Debt - Capital Leases (Details)

Debt - Capital Leases (Details) $ in Millions	Dec. 31, 2018USD ($)
Debt Disclosure [Abstract]
2,019	$ 909
2,020	631
2,021	389
2,022	102
2,023	66
Thereafter	106
Total	2,203
Included in Total
Interest	143
Maintenance	$ 45

Debt - Standby Letters of Credi

Debt - Standby Letters of Credit (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Letters of credit, amount outstanding	$ 86	$ 79
JP Morgan Chase
Debt Instrument [Line Items]
Letters of credit, amount outstanding	20	20
Deutsche Bank
Debt Instrument [Line Items]
Letters of credit, amount outstanding	$ 66	$ 59

Tower Obligations - Narrative (

Tower Obligations - Narrative (Details) $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2012	Dec. 31, 2018USD ($)tower_site	Dec. 31, 2015USD ($)tower_site	Dec. 31, 2012USD ($)tower_site	Dec. 31, 2017USD ($)
Sale Leaseback Transaction [Line Items]
Tower obligations		$ 2,557			$ 2,590
Property and equipment, net		$ 329			$ 402
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 | tower_site				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 | tower_site			600
Net proceeds, financing activities			$ 140
Property subject to failed sale leaseback transaction, number of units | tower_site		150
Imputed interest rate, financial obligation			5.00%

Tower Obligations - Sale Leaseb

Tower Obligations - Sale Leaseback Transaction (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Property and equipment, net	$ 329	$ 402
Long-term financial obligation	$ 2,557	$ 2,590

Tower Obligations - Future Mini

Tower Obligations - Future Minimum Payments (Details) $ in Millions	Dec. 31, 2018USD ($)
Leases [Abstract]
Tower obligation payments, due 2019	$ 195
Tower obligation payments, due 2020 and 2021	391
Tower obligations payments, due 2022 and 2023	392
Tower obligation payments due thereafter	$ 835

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenues	$ 11,445	$ 10,839	$ 10,571	$ 10,455	$ 10,759	$ 10,019	$ 10,213	$ 9,613	$ 43,310	$ 40,604	$ 37,490
Branded postpaid phone revenue
Disaggregation of Revenue [Line Items]
Revenues									19,745	18,371	17,365
Branded postpaid other revenue
Disaggregation of Revenue [Line Items]
Revenues									1,117	1,077	773
Branded postpaid revenues
Disaggregation of Revenue [Line Items]
Revenues									20,862	19,448	18,138
Lease of mobile communication devices and accessories
Disaggregation of Revenue [Line Items]
Revenues									$ 692	$ 877	$ 1,416

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Contract Balances (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Change in Contract with Customer, Asset and Liability [Abstract]
Contract assets included in other current assets	$ 51	$ 140
Contract liabilities included in deferred revenue	645	$ 718
Change in contract assets included in other current assets	(89)
Change in contracts liabilities included in deferred revenue	(73)
Amounts included in the January 1, 2018 contract liability balance	710
Amounts associated with performance obligations satisfied in previous periods	$ 2

Revenue from Contracts with C_5

Revenue from Contracts with Customers - Remaining Performance Obligations, Branded Postpaid Contracts (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Branded postpaid contracts
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 308
Remaining contract duration	24 months
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining contract duration	1 year
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining contract duration	6 years

Revenue from Contracts with C_6

Revenue from Contracts with Customers - Remaining Performance Obligations (Details) $ in Billions	Dec. 31, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 1.1
Remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 1
Remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 1.5
Remaining performance obligation, expected timing of satisfaction, period

Revenue from Contracts with C_7

Revenue from Contracts with Customers - Contract Costs (Details)	12 Months Ended
	Dec. 31, 2018USD ($)
Capitalized Contract Cost [Abstract]
Total deferred incremental costs to obtain contracts	$ 644,000,000
Average amortization period, deferred contract costs	24 months
Amortization of deferred costs	$ 267,000,000
Impairment losses recognized on deferred contract cost assets	$ 0

Employee Compensation and Ben_3

Employee Compensation and Benefit Plans - Narrative (Details) - USD ($) $ in Millions	Jun. 18, 2018	Jun. 13, 2018	Jan. 31, 2018	Dec. 31, 2018
Restricted Stock and Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted or carried over (in shares)				6,259,169
Restricted Stock and Unit Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)				3 years
Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted or carried over (in shares)				3,364,629
Performance Restricted Stock Units | Sprint
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted or carried over (in shares)				1,317,386
Performance Restricted Stock Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)				3 years
Restricted Stock Awards and Incentive Stock Options | Layer3 TV
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Acquisition date fair value			$ 30
2013 Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance (in shares)		18,500,000
Number of shares registered pursuant to the Plan (in shares)	19,345,005

Employee Compensation and Ben_4

Employee Compensation and Benefit Plans - Schedule of Stock-based Compensation Expense and Related Income Tax Benefits (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 424	$ 306	$ 235
Income tax benefit related to stock-based compensation	$ 81	$ 73	$ 80
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 (in USD per share)	$ 61.52	$ 60.21	$ 45.07
Unrecognized compensation expense	$ 547	$ 445	$ 389
Weighted average period to be recognized (years)	1 year 9 months 22 days	1 year 11 months 8 days	2 years
Fair value of stock awards vested	$ 471	$ 503	$ 354

Employee Compensation and Ben_5

Employee Compensation and Benefit Plans - Schedule of Restricted Stock and Unit Awards and Performance Restricted Stock Units Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Aggregate Intrinsic Value
Taxes paid related to net share settlement of stock awards	$ 146	$ 166	$ 121
Minimum
Aggregate Intrinsic Value
Share payout percentage	0.00%
Maximum
Aggregate Intrinsic Value
Share payout percentage	200.00%
Restricted Stock and Unit Awards
Number of Units or Awards
Nonvested, beginning (in shares)	12,061,608
Granted (in shares)	6,259,169
Vested (in shares)	6,455,617
Forfeited (in shares)	854,525
Nonvested, ending (in shares)	11,010,635	12,061,608
Weighted Average Grant Date Fair Value
Nonvested, beginning (in USD per share)	$ 50.69
Granted (in USD per share)	60.44
Vested (in USD per share)	47.89
Forfeited (in USD per share)	56.90
Nonvested, ending (in USD per share)	$ 57.66	$ 50.69
Weighted Average Remaining Contractual Term (Years)
Nonvested, Weighted Average Remaining Contractual Term, beginning (in years)	11 months 16 days	1 year 1 month 6 days
Nonvested, Weighted Average Remaining Contractual Term, ending (in years)	11 months 16 days	1 year 1 month 6 days
Aggregate Intrinsic Value
Nonvested, Aggregate Intrinsic Value, beginning	$ 700	$ 766
Nonvested, Aggregate Intrinsic Value, ending	$ 700	$ 766
Performance Restricted Stock Units
Number of Units or Awards
Nonvested, beginning (in shares)	1,633,935
Granted (in shares)	3,364,629
Vested (in shares)	1,006,769
Forfeited (in shares)	140,241
Nonvested, ending (in shares)	3,851,554	1,633,935
Weighted Average Grant Date Fair Value
Nonvested, beginning (in USD per share)	$ 48.06
Granted (in USD per share)	63.54
Vested (in USD per share)	36.47
Forfeited (in USD per share)	64.14
Nonvested, ending (in USD per share)	$ 64.03	$ 48.06
Weighted Average Remaining Contractual Term (Years)
Nonvested, Weighted Average Remaining Contractual Term, beginning (in years)	1 year 6 months 26 days	1 year 1 month 6 days
Nonvested, Weighted Average Remaining Contractual Term, ending (in years)	1 year 6 months 26 days	1 year 1 month 6 days
Aggregate Intrinsic Value
Nonvested, Aggregate Intrinsic Value, beginning	$ 245	$ 104
Nonvested, Aggregate Intrinsic Value, ending	$ 245	$ 104
Restricted Stock Units and Performance Stock Units
Weighted Average Grant Date Fair Value
Granted (in USD per share)	$ 61.52	$ 60.21	$ 45.07
Aggregate Intrinsic Value
Shares paid for tax withholding for share based compensation (in shares)	2,321,827	2,754,721

Employee Compensation and Ben_6

Employee Compensation and Benefit Plans - Employee Stock Purchase Plan (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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)	2,011,794	1,832,043	1,905,534

Employee Compensation and Ben_7

Employee Compensation and Benefit Plans - Stock Options (Details) - Predecessor Plans - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding and exercisable, beginning (in shares)	373,158
Assumed through acquisition of Layer3 TV (in shares)	118,645
Exercised (in shares)	187,965
Expired/canceled (in shares)	19,027
Outstanding and exercisable, ending (in shares)	284,811	373,158
Exercisable (in shares)	244,224
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding and exercisable, beginning (usd per share)	$ 16.36
Assumed through acquisition of Layer3 TV (usd per share)	15.51
Exercised (usd per share)	18.28
Expired/canceled (usd per share)	18.81
Outstanding and exercisable, ending (usd per share)	14.58	$ 16.36
Exercisable (usd per share)	$ 14.18
Weighted Average Remaining Contractual Term (Years), Outstanding	3 years 9 months	2 years 9 months
Weighted Average Remaining Contractual Term (Years), Exercisable	3 years 1 month
Proceeds from exercise of stock options	$ 3	$ 21

Employee Compensation and Ben_8

Employee Compensation and Benefit Plans - Employee Retirement Savings and Legacy Long-Term Incentive Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Employer retirement savings plan, matching contributions	$ 102,000,000	$ 87,000,000	$ 83,000,000
Long Term Incentive Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred Compensation Arrangement with Individual, Compensation Expense	0	0	0
Payments	$ 0	$ 0	$ 52,000,000

Repurchases of Common Stock - N

Repurchases of Common Stock - Narrative (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended		13 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Apr. 27, 2018	Dec. 06, 2017
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased (in shares)			16,738,758	7,010,889	23,749,647
Average price paid per share (usd per share)			$ 62.96	$ 63.34	$ 63.07
Total Purchase Price			$ 1,054,000,000	$ 444,000,000	$ 1,498,000,000
Affiliated Entity | Deutsche Telekom AG
Equity, Class of Treasury Stock [Line Items]
Additional shares purchased (in shares)	3,300,000	0
Aggregate market value of shares purchased	$ 200,000,000
2017 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount								$ 9,000,000,000	$ 1,500,000,000
2018 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount		$ 500,000,000	$ 500,000,000		$ 500,000,000
Stock repurchase program, increase in authorized amount								$ 7,500,000,000
2018 Stock Repurchase Program | Scenario, Forecast
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount						$ 4,000,000,000	$ 3,000,000,000

Repurchases of Common Stock - S

Repurchases of Common Stock - Schedule of Repurchases of Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended		13 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018
Equity [Abstract]
Number of Shares Repurchased	16,738,758	7,010,889	23,749,647
Average Price Paid Per Share (usd per share)	$ 62.96	$ 63.34	$ 63.07
Total Purchase Price	$ 1,054	$ 444	$ 1,498

Income Taxes - Income Tax Domes

Income Taxes - Income Tax Domestic and Foreign (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
U.S.	$ 3,686	$ 3,274	$ 2,286
Puerto Rico	231	(113)	41
Income before income taxes	$ 3,917	$ 3,161	$ 2,327

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current tax benefit (expense)
Federal	$ 39	$ 0	$ 66
State	(63)	(28)	(29)
Puerto Rico	(25)	(1)	10
Total current tax benefit (expense)	(49)	(29)	47
Deferred tax benefit (expense)
Federal	(750)	1,182	(804)
State	(160)	173	(96)
Puerto Rico	(70)	49	(14)
Total deferred tax (expense) benefit	(980)	1,404	(914)
Total income tax (expense) benefit	$ (1,029)	$ 1,375	$ (867)

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory income tax rate	21.00%	35.00%	35.00%
Effect of law and rate changes	1.90%	(68.90%)	0.80%
Change in valuation allowance	(1.60%)	(11.40%)	1.00%
State taxes, net of federal benefit	4.80%	4.80%	3.20%
Equity-based compensation	(0.60%)	(2.40%)	(2.20%)
Puerto Rico taxes, net of federal benefit	2.40%	(1.50%)	0.00%
Permanent differences	1.30%	0.50%	0.60%
Federal tax credits, net of reserves	(2.90%)	0.30%	(0.50%)
Other, net	0.00%	0.10%	(0.60%)
Effective income tax rate	26.30%	(43.50%)	37.30%

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets
Loss carryforwards	$ 1,526	$ 1,576
Deferred rents	784	759
Reserves and accruals	668	667
Federal and state tax credits	340	298
Other	620	403
Deferred tax assets, gross	3,938	3,703
Valuation allowance	(210)	(273)	$ (573)
Deferred tax assets, net	3,728	3,430
Deferred tax liabilities
Spectrum licenses	5,494	5,038
Property and equipment	2,434	1,840
Other intangible assets	40	41
Other	232	48
Total deferred tax liabilities	8,200	6,967
Net deferred tax liabilities	$ 4,472	$ 3,537

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2016
Income Tax Contingency [Line Items]
Alternative minimum tax credit carryforward		$ 48
Foreign tax credits	$ 298	340
Valuation allowance	273	210	$ 573
Accrued interest and penalties associated with unrecognized tax benefits		0
Net tax benefits	359
Valuation allowance established for impact of TCJA	26
Reduced Federal Benefit of State Items
Income Tax Contingency [Line Items]
Valuation allowance, change in amount	$ 33
Federal
Income Tax Contingency [Line Items]
Unrecognized tax benefits, net operating loss		1,100
Operating loss carryforwards		119
Federal | Research Tax Credit Carryforward
Income Tax Contingency [Line Items]
Foreign tax credits		312
State
Income Tax Contingency [Line Items]
Unrecognized tax benefits, net operating loss		797
Operating loss carryforwards		$ 261

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning of year	$ 412	$ 410	$ 411
Gross increases to tax positions in prior periods	6
Gross decreases to tax positions in prior periods		(10)	(5)
Gross increases due to current period business acquisitions	10	0	0
Gross increases to current period tax positions	34	12	4
Unrecognized tax benefits, end of year	462	412	$ 410
Unrecognized tax benefits that would impact effective tax rate	$ 315	$ 254

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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income	$ 640	$ 795	$ 782	$ 671	$ 2,707	$ 550	$ 581	$ 698	$ 2,888	$ 4,536	$ 1,460
Less: Dividends on mandatory convertible preferred stock					(14)	(13)	(14)	(14)	0	(55)	(55)
Net income attributable to common stockholders	$ 640	$ 795	$ 782	$ 671	$ 2,693	$ 537	$ 567	$ 684	2,888	4,481	1,405
Add: Dividends related to mandatory convertible preferred stock									0	55	0
Net income attributable to common stockholders - diluted									$ 2,888	$ 4,536	$ 1,405
Weighted average shares outstanding - basic (in shares)	849,102,785	847,087,120	847,660,488	855,222,664	837,416,683	831,189,779	830,971,528	827,723,034	849,744,152	831,850,073	822,470,275
Effect of dilutive securities:
Outstanding stock options and unvested stock awards (in shares)									8,546,022	9,200,873	10,584,270
Mandatory convertible preferred stock (in shares)									0	30,736,504	0
Weighted average shares outstanding - diluted (in shares)	856,344,347	853,852,764	852,040,670	862,244,084	871,501,578	871,420,065	870,457,181	869,395,984	858,290,174	871,787,450	833,054,545
Earnings per share - basic (in USD per share)	$ 0.75	$ 0.94	$ 0.92	$ 0.78	$ 3.22	$ 0.65	$ 0.68	$ 0.83	$ 3.40	$ 5.39	$ 1.71
Earnings per share - diluted (in USD per share)	$ 0.75	$ 0.93	$ 0.92	$ 0.78	$ 3.11	$ 0.63	$ 0.67	$ 0.80	$ 3.36	$ 5.20	$ 1.69
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)									148,422	33,980	3,528,683
Mandatory convertible preferred stock (in shares)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)									0	0	32,238,000

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - Mandatory Convertible Preferred Stock Series A - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Preferred shares authorized (in shares)	100,000,000
Preferred stock rate (percent)	5.50%
Preferred stock, par value (in USD per share)	$ 0.00001
Preferred shares outstanding (in shares)	0	0

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Millions	1 Months Ended		12 Months Ended
	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)agreement	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Oct. 31, 2018USD ($)
Operating Leased Assets [Line Items]
Operating leases, due 2019			$ 2,700
Operating leases, total due 2020 and 2021			4,700
Operating leases, total dude 2022 and 2023			3,300
Operating leases total due thereafter			3,800
Rent expense under operating leases			3,000	$ 2,900	$ 2,800
Purchase obligation, due 2019			3,400
Purchase obligation, due 2020 and 2021			2,800
Purchase obligation, Due 2022 and 2023			1,800
Purchase obligation total due thereafter			$ 1,400
Number of purchase agreements | agreement			4
Interest Rate Contract | Cash Flow Hedging
Operating Leased Assets [Line Items]
Aggregate notional amount						$ 9,600
Fair value of derivative instrument			$ 447
Sprint
Operating Leased Assets [Line Items]
Total long-term lease commitment			$ 535
Minimum
Operating Leased Assets [Line Items]
Initial term of third-party agreements			1 year
Purchase commitment period			15 years
Maximum
Operating Leased Assets [Line Items]
Initial term of third-party agreements			3 years
Purchase commitment period			20 years
Network Equipment | Minimum
Operating Leased Assets [Line Items]
Network equipment purchase agreement			$ 377
Network Equipment | Maximum
Operating Leased Assets [Line Items]
Network equipment purchase agreement	$ 3,500	$ 3,500
Network Equipment, Amended Agreement | Minimum
Operating Leased Assets [Line Items]
Network equipment purchase agreement			$ 259
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 Informat_3

Additional Financial Information - Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Supplemental Financial Statement Elements [Abstract]
Accounts payable	$ 5,487	$ 6,182
Payroll and related benefits	709	614
Property and other taxes, including payroll	642	620
Interest	227	253
Commissions	243	324
Network decommissioning	65	92
Toll and interconnect	157	109
Advertising	76	46
Other	135	288
Accounts payable and accrued liabilities	7,741	8,528
Accounts Payable and Accrued Liabilities
Accounts Payable and Accrued Liabilities [Line Items]
Outstanding checks	$ 630	$ 455

Additional Financial Informat_4

Additional Financial Information - Narrative (Details) - Hurricane - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Significant Transactions [Line Items]
Reimbursement payments from insurance carriers	$ 307,000,000
Insurance receivable	5,000,000	$ 93,000,000
Cost of Sales
Significant Transactions [Line Items]
Cost of services	25,000,000	36,000,000
Operating income (loss)
Significant Transactions [Line Items]
Cost of services	61,000,000	294,000,000	$ 0
Service | Cost of Sales
Significant Transactions [Line Items]
Cost of services	$ 59,000,000	$ 198,000,000

Additional Financial Informat_5

Additional Financial Information - Schedule of Hurricane Impacts (Details) - Hurricane - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues
Unusual or Infrequent Item, or Both [Line Items]
Gross	$ 0	$ (56,000,000)
Gross, Operating expenses	0	56,000,000
Reim- bursement, Revenues	71,000,000	0
Reim- bursement	(71,000,000)	0
Net	71,000,000	(56,000,000)
Net	(71,000,000)	56,000,000
Revenues | Branded postpaid revenues
Unusual or Infrequent Item, or Both [Line Items]
Gross	0	(37,000,000)
Gross, Operating expenses	0	37,000,000
Reim- bursement, Revenues	0	0
Reim- bursement	0	0
Net	0	(37,000,000)
Net	0	37,000,000
Revenues | Branded postpaid phone revenue
Unusual or Infrequent Item, or Both [Line Items]
Gross	0	(35,000,000)
Gross, Operating expenses	0	35,000,000
Reim- bursement, Revenues	0	0
Reim- bursement	0	0
Net	0	(35,000,000)
Net	0	35,000,000
Revenues | Branded prepaid revenues
Unusual or Infrequent Item, or Both [Line Items]
Gross	0	(11,000,000)
Gross, Operating expenses	0	11,000,000
Reim- bursement, Revenues	0	0
Reim- bursement	0	0
Net	0	(11,000,000)
Net	0	11,000,000
Revenues | Service
Unusual or Infrequent Item, or Both [Line Items]
Gross	0	(48,000,000)
Gross, Operating expenses	0	48,000,000
Reim- bursement, Revenues	0	0
Reim- bursement	0	0
Net	0	(48,000,000)
Net	0	48,000,000
Revenues | Equipment
Unusual or Infrequent Item, or Both [Line Items]
Gross	0	(8,000,000)
Gross, Operating expenses	0	8,000,000
Reim- bursement, Revenues	0	0
Reim- bursement	0	0
Net	0	(8,000,000)
Net	0	8,000,000
Revenues | Other revenues
Unusual or Infrequent Item, or Both [Line Items]
Gross	0	0
Gross, Operating expenses	0	0
Reim- bursement, Revenues	71,000,000	0
Reim- bursement	(71,000,000)	0
Net	71,000,000	0
Net	(71,000,000)	0
Cost of Sales
Unusual or Infrequent Item, or Both [Line Items]
Gross	(25,000,000)	(36,000,000)
Gross, Operating expenses	25,000,000	36,000,000
Cost of Sales | Service
Unusual or Infrequent Item, or Both [Line Items]
Gross	(59,000,000)	(198,000,000)
Gross, Operating expenses	59,000,000	198,000,000
Reim- bursement, Revenues	135,000,000	93,000,000
Reim- bursement	(135,000,000)	(93,000,000)
Net	76,000,000	(105,000,000)
Net	(76,000,000)	105,000,000
Cost of Sales | Equipment
Unusual or Infrequent Item, or Both [Line Items]
Gross	(1,000,000)	(4,000,000)
Gross, Operating expenses	1,000,000	4,000,000
Reim- bursement, Revenues	0	0
Reim- bursement	0	0
Net	(1,000,000)	(4,000,000)
Net	1,000,000	4,000,000
Selling, general and administrative
Unusual or Infrequent Item, or Both [Line Items]
Gross	(1,000,000)	(36,000,000)
Gross, Operating expenses	1,000,000	36,000,000
Reim- bursement, Revenues	13,000,000	0
Reim- bursement	(13,000,000)	0
Net	12,000,000	(36,000,000)
Net	(12,000,000)	36,000,000
Bad debt expense
Unusual or Infrequent Item, or Both [Line Items]
Gross	0	(20,000,000)
Gross, Operating expenses	0	20,000,000
Reim- bursement, Revenues	0	0
Reim- bursement	0	0
Net	0	(20,000,000)
Net	0	20,000,000
Total operating expenses
Unusual or Infrequent Item, or Both [Line Items]
Gross	(61,000,000)	(238,000,000)
Gross, Operating expenses	61,000,000	238,000,000
Reim- bursement, Revenues	148,000,000	93,000,000
Reim- bursement	(148,000,000)	(93,000,000)
Net	87,000,000	(145,000,000)
Net	(87,000,000)	145,000,000
Operating income (loss)
Unusual or Infrequent Item, or Both [Line Items]
Gross	(61,000,000)	(294,000,000)	$ 0
Gross, Operating expenses	61,000,000	294,000,000	$ 0
Reim- bursement, Revenues	219,000,000	93,000,000
Reim- bursement	(219,000,000)	(93,000,000)
Net	158,000,000	(201,000,000)
Net	(158,000,000)	201,000,000
Net income (loss)
Unusual or Infrequent Item, or Both [Line Items]
Gross	(41,000,000)	(193,000,000)
Gross, Operating expenses	41,000,000	193,000,000
Reim- bursement, Revenues	140,000,000	63,000,000
Reim- bursement	(140,000,000)	(63,000,000)
Net	99,000,000	(130,000,000)
Net	$ (99,000,000)	$ 130,000,000
Earnings per share - basic
Unusual or Infrequent Item, or Both [Line Items]
Gross, Earnings per share (in USD per share)	$ (0.05)	$ (0.23)
Reimbursement, Earnings per share (in USD per share)	0.17	0.07
Net, Earnings per share (in USD per share)	0.12	(0.16)
Earnings per share - diluted
Unusual or Infrequent Item, or Both [Line Items]
Gross, Earnings per share (in USD per share)	(0.05)	(0.22)
Reimbursement, Earnings per share (in USD per share)	0.17	0.07
Net, Earnings per share (in USD per share)	$ 0.12	$ (0.15)

Additional Financial Informat_6

Additional Financial Information - Related Party Transactions (Details) - Affiliated Entity - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Discount related to roaming expenses	$ 0	$ 0	$ (15)
Fees incurred for use of the T-Mobile brand	84	79	74
Expenses for telecommunications and IT services	0	12	25
International long distance agreement	36	55	60
Reimbursement of certain administrative expenses	$ 11	$ 11	$ 11

Guarantor Financial Informati_3

Guarantor Financial Information - Condensed Consolidating Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 1,203		$ 1,219	$ 5,500	$ 4,582
Accounts receivable, net	1,769		1,915
Equipment installment plan receivables, net	2,538		2,290
Accounts receivable from affiliates	11		22
Inventories	1,084		1,566
Other current assets	1,676	$ 2,043	1,903
Total current assets	8,281		8,915
Property and equipment, net	23,359		22,196
Goodwill	1,901		1,683
Spectrum licenses	35,559		35,366
Other intangible assets, net	198		217
Investments in subsidiaries, net	0		0
Intercompany receivables and note receivables	0		0
Equipment installment plan receivables due after one year, net	1,547		1,274
Other assets	1,623	1,062	912
Total assets	72,468		70,563
Current liabilities
Accounts payable and accrued liabilities	7,741		8,528
Payables to affiliates	200		182
Short-term debt	841		1,612
Deferred revenue	698	783	779
Other current liabilities	787		414
Total current liabilities	10,267		11,515
Long-term debt	12,124		12,121
Long-term debt to affiliates	14,582		14,586
Tower obligations	2,557		2,590
Deferred tax liabilities	4,472	$ 3,610	3,537
Deferred rent expense	2,781		2,720
Negative carrying value of subsidiaries, net	0		0
Intercompany payables and debt	0		0
Other long-term liabilities	967		935
Total long-term liabilities	37,483		36,489
Total stockholders' equity (deficit)	24,718		22,559	18,236	16,557
Total liabilities and stockholders' equity	72,468		70,563
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
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	(71,830)		(63,522)
Intercompany receivables and note receivables	(5,174)		(8,503)
Equipment installment plan receivables due after one year, net	0		0
Other assets	(145)		(140)
Total assets	(77,149)		(72,165)
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	(145)		(140)
Deferred rent expense	0		0
Negative carrying value of subsidiaries, net	(676)		(629)
Intercompany payables and debt	(5,174)		(8,503)
Other long-term liabilities	0		0
Total long-term liabilities	(5,995)		(9,272)
Total stockholders' equity (deficit)	(71,154)		(62,893)
Total liabilities and stockholders' equity	(77,149)		(72,165)
Parent | Reportable Legal Entities
Current assets
Cash and cash equivalents	2		74	358	378
Accounts receivable, net	0		0
Equipment installment plan receivables, net	0		0
Accounts receivable from affiliates	0		0
Inventories	0		0
Other current assets	0		0
Total current assets	2		74
Property and equipment, net	0		0
Goodwill	0		0
Spectrum licenses	0		0
Other intangible assets, net	0		0
Investments in subsidiaries, net	25,314		22,534
Intercompany receivables and note receivables	0		0
Equipment installment plan receivables due after one year, net	0		0
Other assets	0		0
Total assets	25,316		22,608
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		17
Total current liabilities	0		17
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	598		32
Other long-term liabilities	0		0
Total long-term liabilities	598		32
Total stockholders' equity (deficit)	24,718		22,559
Total liabilities and stockholders' equity	25,316		22,608
Issuer | Reportable Legal Entities
Current assets
Cash and cash equivalents	1		1	2,733	1,767
Accounts receivable, net	0		0
Equipment installment plan receivables, net	0		0
Accounts receivable from affiliates	0		0
Inventories	0		0
Other current assets	0		0
Total current assets	1		1
Property and equipment, net	0		0
Goodwill	0		0
Spectrum licenses	0		0
Other intangible assets, net	0		0
Investments in subsidiaries, net	46,516		40,988
Intercompany receivables and note receivables	5,174		8,503
Equipment installment plan receivables due after one year, net	0		0
Other assets	7		2
Total assets	51,698		49,494
Current liabilities
Accounts payable and accrued liabilities	228		253
Payables to affiliates	157		146
Short-term debt	0		999
Deferred revenue	0		0
Other current liabilities	447		0
Total current liabilities	832		1,398
Long-term debt	10,950		10,911
Long-term debt to affiliates	14,582		14,586
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	20		65
Total long-term liabilities	25,552		25,562
Total stockholders' equity (deficit)	25,314		22,534
Total liabilities and stockholders' equity	51,698		49,494
Guarantor Subsidiaries | Reportable Legal Entities
Current assets
Cash and cash equivalents	1,079		1,086	2,342	2,364
Accounts receivable, net	1,510		1,659
Equipment installment plan receivables, net	2,538		2,290
Accounts receivable from affiliates	11		22
Inventories	1,084		1,566
Other current assets	1,031		1,275
Total current assets	7,253		7,898
Property and equipment, net	23,062		21,890
Goodwill	1,683		1,683
Spectrum licenses	35,559		35,366
Other intangible assets, net	116		217
Investments in subsidiaries, net	0		0
Intercompany receivables and note receivables	0		0
Equipment installment plan receivables due after one year, net	1,547		1,274
Other assets	1,540		814
Total assets	70,760		69,142
Current liabilities
Accounts payable and accrued liabilities	7,240		8,014
Payables to affiliates	43		36
Short-term debt	841		613
Deferred revenue	698		779
Other current liabilities	164		192
Total current liabilities	8,986		9,634
Long-term debt	1,174		1,210
Long-term debt to affiliates	0		0
Tower obligations	384		392
Deferred tax liabilities	4,617		3,677
Deferred rent expense	2,781		2,720
Negative carrying value of subsidiaries, net	676		629
Intercompany payables and debt	4,234		8,201
Other long-term liabilities	926		866
Total long-term liabilities	14,792		17,695
Total stockholders' equity (deficit)	46,982		41,813
Total liabilities and stockholders' equity	70,760		69,142
Non-Guarantor Subsidiaries | Reportable Legal Entities
Current assets
Cash and cash equivalents	121		58	$ 67	$ 73
Accounts receivable, net	259		256
Equipment installment plan receivables, net	0		0
Accounts receivable from affiliates	0		0
Inventories	0		0
Other current assets	645		628
Total current assets	1,025		942
Property and equipment, net	297		306
Goodwill	218		0
Spectrum licenses	0		0
Other intangible assets, net	82		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	221		236
Total assets	1,843		1,484
Current liabilities
Accounts payable and accrued liabilities	273		261
Payables to affiliates	0		0
Short-term debt	0		0
Deferred revenue	0		0
Other current liabilities	176		205
Total current liabilities	449		466
Long-term debt	0		0
Long-term debt to affiliates	0		0
Tower obligations	2,173		2,198
Deferred tax liabilities	0		0
Deferred rent expense	0		0
Negative carrying value of subsidiaries, net	0		0
Intercompany payables and debt	342		270
Other long-term liabilities	21		4
Total long-term liabilities	2,536		2,472
Total stockholders' equity (deficit)	(1,142)		(1,454)
Total liabilities and stockholders' equity	$ 1,843		$ 1,484

Guarantor Financial Informati_4

Guarantor Financial Information - Condensed Consolidating Statement of Comprehensive Income Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues
Revenues	$ 11,445	$ 10,839	$ 10,571	$ 10,455	$ 10,759	$ 10,019	$ 10,213	$ 9,613	$ 43,310	$ 40,604	$ 37,490
Operating expenses
Selling, general and administrative									13,161	12,259	11,378
Depreciation and amortization									6,486	5,984	6,243
Cost of Metro business combination											104
Gains on disposal of spectrum licenses					(168)	(29)	(1)	(37)	0	(235)	(835)
Total operating expense									38,001	35,716	33,440
Operating income	1,137	1,440	1,450	1,282	1,112	1,323	1,416	1,037	5,309	4,888	4,050
Other income (expense)
Interest expense									(835)	(1,111)	(1,418)
Interest expense to affiliates									(522)	(560)	(312)
Interest income									19	17	13
Other income (expense), net									(54)	(73)	(6)
Total other expense, net									(1,392)	(1,727)	(1,723)
Income before income taxes									3,917	3,161	2,327
Income tax (expense) benefit									(1,029)	1,375	(867)
Earnings of subsidiaries									0	0	0
Net income	640	795	782	671	2,707	550	581	698	2,888	4,536	1,460
Dividends on preferred stock					(14)	(13)	(14)	(14)	0	(55)	(55)
Net income attributable to common stockholders	$ 640	$ 795	$ 782	$ 671	$ 2,693	$ 537	$ 567	$ 684	2,888	4,481	1,405
Other comprehensive income (loss), net of tax									(332)	7	2
Total comprehensive income									2,556	4,543	1,462
Service
Revenues
Revenues									31,992	30,160	27,844
Operating expenses
Cost of services and equipment sales									6,307	6,100	5,731
Product
Revenues
Revenues									10,009	9,375	8,727
Operating expenses
Cost of services and equipment sales									12,047	11,608	10,819
Other revenues
Revenues
Revenues									1,309	1,069	919
Consolidating and Eliminating Adjustments
Revenues
Revenues									(1,240)	(1,117)	(1,228)
Operating expenses
Selling, general and administrative									(1,038)	(873)	(811)
Depreciation and amortization									0	0	0
Cost of Metro business combination											0
Gains on disposal of spectrum licenses									0	0	0
Total operating expense									(1,240)	(1,117)	(1,228)
Operating income									0	0	0
Other income (expense)
Interest expense									0	0	0
Interest expense to affiliates									21	23	0
Interest income									(21)	(23)	0
Other income (expense), net									0	0	0
Total other expense, net									0	0	0
Income before income taxes									0	0	0
Income tax (expense) benefit									0	0	0
Earnings of subsidiaries									(6,904)	(10,440)	(4,326)
Net income									(6,904)	(10,440)	(4,326)
Dividends on preferred stock									0	0	0
Net income attributable to common stockholders									(6,904)	(10,440)	(4,326)
Other comprehensive income (loss), net of tax									216	(14)	(6)
Total comprehensive income									(6,688)	(10,454)	(4,332)
Consolidating and Eliminating Adjustments | Service
Revenues
Revenues									(978)	(847)	(792)
Operating expenses
Cost of services and equipment sales									0	0	0
Consolidating and Eliminating Adjustments | Product
Revenues
Revenues									(201)	(245)	(418)
Operating expenses
Cost of services and equipment sales									(202)	(244)	(417)
Consolidating and Eliminating Adjustments | Other revenues
Revenues
Revenues									(61)	(25)	(18)
Parent | Reportable Legal Entities
Revenues
Revenues									0	0	0
Operating expenses
Selling, general and administrative									0	0	0
Depreciation and amortization									0	0	0
Cost of Metro business combination											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									0	1	0
Other income (expense), net									0	0	0
Total other expense, net									0	1	0
Income before income taxes									0	1	0
Income tax (expense) benefit									0	0	0
Earnings of subsidiaries									2,888	4,535	1,460
Net income									2,888	4,536	1,460
Dividends on preferred stock									0	(55)	(55)
Net income attributable to common stockholders									2,888	4,481	1,405
Other comprehensive income (loss), net of tax									(332)	7	2
Total comprehensive income									2,556	4,543	1,462
Parent | Reportable Legal Entities | Service
Revenues
Revenues									0	0	0
Operating expenses
Cost of services and equipment sales									0	0	0
Parent | Reportable Legal Entities | Product
Revenues
Revenues									0	0	0
Operating expenses
Cost of services and equipment sales									0	0	0
Parent | Reportable Legal Entities | Other revenues
Revenues
Revenues									0	0	0
Issuer | Reportable Legal Entities
Revenues
Revenues									29	3	3
Operating expenses
Selling, general and administrative									11	0	0
Depreciation and amortization									0	0	0
Cost of Metro business combination											0
Gains on disposal of spectrum licenses									0	0	0
Total operating expense									11	0	0
Operating income									18	3	3
Other income (expense)
Interest expense									(528)	(811)	(1,147)
Interest expense to affiliates									(522)	(560)	(312)
Interest income									23	29	31
Other income (expense), net									(87)	(88)	2
Total other expense, net									(1,114)	(1,430)	(1,426)
Income before income taxes									(1,096)	(1,427)	(1,423)
Income tax (expense) benefit									0	0	0
Earnings of subsidiaries									3,984	5,962	2,883
Net income									2,888	4,535	1,460
Dividends on preferred stock									0	0	0
Net income attributable to common stockholders									2,888	4,535	1,460
Other comprehensive income (loss), net of tax									(332)	7	2
Total comprehensive income									2,556	4,542	1,462
Issuer | Reportable Legal Entities | Service
Revenues
Revenues									0	0	0
Operating expenses
Cost of services and equipment sales									0	0	0
Issuer | Reportable Legal Entities | Product
Revenues
Revenues									0	0	0
Operating expenses
Cost of services and equipment sales									0	0	0
Issuer | Reportable Legal Entities | Other revenues
Revenues
Revenues									29	3	3
Guarantor Subsidiaries | Reportable Legal Entities
Revenues
Revenues									41,952	39,393	36,497
Operating expenses
Selling, general and administrative									13,203	12,276	11,321
Depreciation and amortization									6,396	5,914	6,165
Cost of Metro business combination											104
Gains on disposal of spectrum licenses									0	(235)	(835)
Total operating expense									37,094	34,880	32,671
Operating income									4,858	4,513	3,826
Other income (expense)
Interest expense									(114)	(109)	(82)
Interest expense to affiliates									(21)	(23)	0
Interest income									16	10	(18)
Other income (expense), net									33	16	(8)
Total other expense, net									(86)	(106)	(108)
Income before income taxes									4,772	4,407	3,718
Income tax (expense) benefit									(981)	1,527	(857)
Earnings of subsidiaries									32	(57)	(17)
Net income									3,823	5,877	2,844
Dividends on preferred stock									0	0	0
Net income attributable to common stockholders									3,823	5,877	2,844
Other comprehensive income (loss), net of tax									116	7	2
Total comprehensive income									3,939	5,884	2,846
Guarantor Subsidiaries | Reportable Legal Entities | Service
Revenues
Revenues									30,631	28,894	26,613
Operating expenses
Cost of services and equipment sales									6,257	6,076	5,707
Guarantor Subsidiaries | Reportable Legal Entities | Product
Revenues
Revenues									10,208	9,620	9,145
Operating expenses
Cost of services and equipment sales									11,238	10,849	10,209
Guarantor Subsidiaries | Reportable Legal Entities | Other revenues
Revenues
Revenues									1,113	879	739
Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenues
Revenues									2,569	2,325	2,218
Operating expenses
Selling, general and administrative									985	856	868
Depreciation and amortization									90	70	78
Cost of Metro business combination											0
Gains on disposal of spectrum licenses									0	0	0
Total operating expense									2,136	1,953	1,997
Operating income									433	372	221
Other income (expense)
Interest expense									(193)	(191)	(189)
Interest expense to affiliates									0	0	0
Interest income									1	0	0
Other income (expense), net									0	(1)	0
Total other expense, net									(192)	(192)	(189)
Income before income taxes									241	180	32
Income tax (expense) benefit									(48)	(152)	(10)
Earnings of subsidiaries									0	0	0
Net income									193	28	22
Dividends on preferred stock									0	0	0
Net income attributable to common stockholders									193	28	22
Other comprehensive income (loss), net of tax									0	0	2
Total comprehensive income									193	28	24
Non-Guarantor Subsidiaries | Reportable Legal Entities | Service
Revenues
Revenues									2,339	2,113	2,023
Operating expenses
Cost of services and equipment sales									50	24	24
Non-Guarantor Subsidiaries | Reportable Legal Entities | Product
Revenues
Revenues									2	0	0
Operating expenses
Cost of services and equipment sales									1,011	1,003	1,027
Non-Guarantor Subsidiaries | Reportable Legal Entities | Other revenues
Revenues
Revenues									$ 228	$ 212	$ 195

Guarantor Financial Informati_5

Guarantor Financial Information - Condensed Consolidating Statement of Cash Flows 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, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net cash provided by (used in) operating activities					$ 3,899	$ 3,831	$ 2,779
Investing activities
Purchases of property and equipment					(5,541)	(5,237)	(4,702)
Purchases of spectrum licenses and other intangible assets, including deposits					(127)	(5,828)	(3,968)
Proceeds related to beneficial interests in securitization transactions					5,406	4,319	3,356
Sales of short-term investments					0	0	2,998
Acquisition of companies, net of cash acquired					(338)	0	0
Equity investment in subsidiary					0	0
Other, net					21	1	(8)
Net cash used in investing activities					(579)	(6,745)	(2,324)
Financing activities
Proceeds from issuance of long-term debt					2,494	10,480	997
Proceeds from borrowing on revolving credit facility					6,265	2,910	0
Repayments of revolving credit facility					(6,265)	(2,910)	0
Repayments of capital lease obligations					(700)	(486)	(205)
Repayments of short-term debt for purchases of inventory, property and equipment, net					(300)	(300)	(150)
Repayments of long-term debt					(3,349)	(10,230)	(20)
Repurchases of common stock					(1,071)	(427)	0
Intercompany advances, net					0	0	0
Equity investment from parent					0	0
Tax withholdings on share-based awards					(146)	(166)	(121)
Dividends on preferred stock	$ 14	$ 13	$ 14	$ 14	0	55	55
Cash payments for debt prepayment or debt extinguishment costs					(212)	(188)	0
Intercompany dividend paid					0	0	0
Dividends on preferred stock					0	(55)	(55)
Other, net					(52)	5	17
Net cash (used in) provided by financing activities					(3,336)	(1,367)	463
Change in cash and cash equivalents					(16)	(4,281)	918
Beginning of period				5,500	1,219	5,500	4,582
End of period	1,219				1,203	1,219	5,500
Consolidating and Eliminating Adjustments
Operating activities
Net cash provided by (used in) operating activities					(220)	(100)	(110)
Investing activities
Purchases of property and equipment					0	0	0
Purchases of spectrum licenses and other intangible assets, including deposits					0	0	0
Proceeds related to beneficial interests in securitization transactions					0	0	0
Sales of short-term investments							0
Acquisition of companies, net of cash acquired					0
Equity investment in subsidiary					43	308
Other, net					0	0	0
Net cash used in investing activities					43	308	0
Financing activities
Proceeds from issuance of long-term debt					0	0	0
Proceeds from borrowing on revolving credit facility					0	0
Repayments of revolving credit facility					0	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	0
Repurchases of common stock					0	0
Intercompany advances, net					0	0	0
Equity investment from parent					(43)	(308)
Tax withholdings on share-based awards					0	0	0
Dividends on preferred stock					0	0	0
Cash payments for debt prepayment or debt extinguishment costs					0	0
Intercompany dividend paid					220	100	110
Dividends on preferred stock							0
Other, net					0	0	0
Net cash (used in) provided by financing activities					177	(208)	110
Change in cash and cash equivalents					0	0	0
Beginning of period				0	0	0	0
End of period	0				0	0	0
Parent | Reportable Legal Entities
Operating activities
Net cash provided by (used in) operating activities					0	1	6
Investing activities
Purchases of property and equipment					0	0	0
Purchases of spectrum licenses and other intangible assets, including deposits					0	0	0
Proceeds related to beneficial interests in securitization transactions					0	0	0
Sales of short-term investments							0
Acquisition of companies, net of cash acquired					0
Equity investment in subsidiary					0	(308)
Other, net					0	0	0
Net cash used in investing activities					0	(308)	0
Financing activities
Proceeds from issuance of long-term debt					0	0	0
Proceeds from borrowing on revolving credit facility					0	0
Repayments of revolving credit facility					0	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	0
Repurchases of common stock					(1,071)	(427)
Intercompany advances, net					995	484	0
Equity investment from parent					0	0
Tax withholdings on share-based awards					0	0	0
Dividends on preferred stock					0	55	55
Cash payments for debt prepayment or debt extinguishment costs					0	0
Intercompany dividend paid					0	0	0
Dividends on preferred stock							(55)
Other, net					4	21	29
Net cash (used in) provided by financing activities					(72)	23	(26)
Change in cash and cash equivalents					(72)	(284)	(20)
Beginning of period				358	74	358	378
End of period	74				2	74	358
Issuer | Reportable Legal Entities
Operating activities
Net cash provided by (used in) operating activities					(1,254)	(1,613)	(1,335)
Investing activities
Purchases of property and equipment					0	0	0
Purchases of spectrum licenses and other intangible assets, including deposits					0	0	0
Proceeds related to beneficial interests in securitization transactions					0	0	0
Sales of short-term investments							2,000
Acquisition of companies, net of cash acquired					0
Equity investment in subsidiary					0	0
Other, net					(7)	0	0
Net cash used in investing activities					(7)	0	2,000
Financing activities
Proceeds from issuance of long-term debt					2,494	10,480	997
Proceeds from borrowing on revolving credit facility					6,265	2,910
Repayments of revolving credit facility					0	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	0
Repurchases of common stock					0	0
Intercompany advances, net					(7,498)	(14,817)	(696)
Equity investment from parent					0	308
Tax withholdings on share-based awards					0	0	0
Dividends on preferred stock					0	0	0
Cash payments for debt prepayment or debt extinguishment costs					0	0
Intercompany dividend paid					0	0	0
Dividends on preferred stock							0
Other, net					0	0	0
Net cash (used in) provided by financing activities					1,261	(1,119)	301
Change in cash and cash equivalents					0	(2,732)	966
Beginning of period				2,733	1	2,733	1,767
End of period	1				1	1	2,733
Guarantor Subsidiaries | Reportable Legal Entities
Operating activities
Net cash provided by (used in) operating activities					10,483	9,761	7,516
Investing activities
Purchases of property and equipment					(5,505)	(5,237)	(4,702)
Purchases of spectrum licenses and other intangible assets, including deposits					(127)	(5,828)	(3,968)
Proceeds related to beneficial interests in securitization transactions					53	43	25
Sales of short-term investments							998
Acquisition of companies, net of cash acquired					(338)
Equity investment in subsidiary					(43)	0
Other, net					28	1	(8)
Net cash used in investing activities					(5,932)	(11,021)	(7,655)
Financing activities
Proceeds from issuance of long-term debt					0	0	0
Proceeds from borrowing on revolving credit facility					0	0
Repayments of revolving credit facility					(6,265)	(2,910)
Repayments of capital lease obligations					(698)	(486)	(205)
Repayments of short-term debt for purchases of inventory, property and equipment, net					(300)	(300)	(150)
Repayments of long-term debt					(3,349)	(10,230)	(20)
Repurchases of common stock					0	0
Intercompany advances, net					6,468	14,300	625
Equity investment from parent					0	0
Tax withholdings on share-based awards					(146)	(166)	(121)
Dividends on preferred stock					0	0	0
Cash payments for debt prepayment or debt extinguishment costs					(212)	(188)
Intercompany dividend paid					0	0	0
Dividends on preferred stock							0
Other, net					(56)	(16)	(12)
Net cash (used in) provided by financing activities					(4,558)	4	117
Change in cash and cash equivalents					(7)	(1,256)	(22)
Beginning of period				2,342	1,086	2,342	2,364
End of period	1,086				1,079	1,086	2,342
Non-Guarantor Subsidiaries | Reportable Legal Entities
Operating activities
Net cash provided by (used in) operating activities					(5,110)	(4,218)	(3,298)
Investing activities
Purchases of property and equipment					(36)	0	0
Purchases of spectrum licenses and other intangible assets, including deposits					0	0	0
Proceeds related to beneficial interests in securitization transactions					5,353	4,276	3,331
Sales of short-term investments							0
Acquisition of companies, net of cash acquired					0
Equity investment in subsidiary					0	0
Other, net					0	0	0
Net cash used in investing activities					5,317	4,276	3,331
Financing activities
Proceeds from issuance of long-term debt					0	0	0
Proceeds from borrowing on revolving credit facility					0	0
Repayments of revolving credit facility					0	0
Repayments of capital lease obligations					(2)	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	0
Repurchases of common stock					0	0
Intercompany advances, net					35	33	71
Equity investment from parent					43	0
Tax withholdings on share-based awards					0	0	0
Dividends on preferred stock					0	0	0
Cash payments for debt prepayment or debt extinguishment costs					0	0
Intercompany dividend paid					(220)	(100)	(110)
Dividends on preferred stock							0
Other, net					0	0	0
Net cash (used in) provided by financing activities					(144)	(67)	(39)
Change in cash and cash equivalents					63	(9)	(6)
Beginning of period				$ 67	58	67	73
End of period	$ 58				$ 121	$ 58	$ 67

Quarterly Financial Informati_3

Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information [Abstract]
Total revenues	$ 11,445	$ 10,839	$ 10,571	$ 10,455	$ 10,759	$ 10,019	$ 10,213	$ 9,613	$ 43,310	$ 40,604	$ 37,490
Operating income	1,137	1,440	1,450	1,282	1,112	1,323	1,416	1,037	5,309	4,888	4,050
Net income	640	795	782	671	2,707	550	581	698	2,888	4,536	1,460
Dividends on preferred stock					(14)	(13)	(14)	(14)	0	(55)	(55)
Net income attributable to common stockholders	$ 640	$ 795	$ 782	$ 671	$ 2,693	$ 537	$ 567	$ 684	$ 2,888	$ 4,481	$ 1,405
Earnings per share - basic (in USD per share)	$ 0.75	$ 0.94	$ 0.92	$ 0.78	$ 3.22	$ 0.65	$ 0.68	$ 0.83	$ 3.40	$ 5.39	$ 1.71
Earnings per share - diluted (in USD per share)	$ 0.75	$ 0.93	$ 0.92	$ 0.78	$ 3.11	$ 0.63	$ 0.67	$ 0.80	$ 3.36	$ 5.20	$ 1.69
Weighted average shares outstanding - basic (in shares)	849,102,785	847,087,120	847,660,488	855,222,664	837,416,683	831,189,779	830,971,528	827,723,034	849,744,152	831,850,073	822,470,275
Weighted average shares outstanding - diluted (in shares)	856,344,347	853,852,764	852,040,670	862,244,084	871,501,578	871,420,065	870,457,181	869,395,984	858,290,174	871,787,450	833,054,545
Gains on disposal of spectrum licenses					$ (168)	$ (29)	$ (1)	$ (37)	$ 0	$ (235)	$ (835)
Net tax benefit associated with enactment of the TCJA					$ 2,200