United States Cellular Corporat (UZD) 10-K 26 Feb 18 2017 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Jan. 31, 2018	Jun. 30, 2017
Entity Registrant Name	United States Cellular Corporation
Entity Central Index Key	821,130
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 540,716,391
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	USM
Common Shares
Entity Common Stock, Shares Outstanding		52,122,000
Series A Common Shares
Entity Common Stock, Shares Outstanding		33,006,000

Consolidated Statement Of Opera

Consolidated Statement Of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating revenues
Service	$ 2,978	$ 3,081	$ 3,384
Equipment sales	912	909	647
Total operating revenues	3,890	3,990	4,031
Operating expenses
System operations (excluding Depreciation, amortization and accretion reported below)	732	760	775
Cost of equipment sold	1,071	1,081	1,053
Selling, general and administrative (including charges from affiliates of $85 million, $94 million and $96 million in 2017, 2016 and 2015)	1,412	1,480	1,494
Depreciation, amortization and accretion	615	618	607
Loss on impairment of goodwill	370	0	0
(Gain) loss on asset disposals, net	17	22	16
(Gain) loss on sale of business and other exit costs, net	(1)		(114)
(Gain) loss on license sales and exchanges, net	(22)	(19)	(147)
Total operating expenses	4,194	3,942	3,684
Operating income (loss)	(304)	48	347
Investment and other income (expense)
Equity in earnings of unconsolidated entities	137	140	140
Interest and dividend income	8	6	2
Interest expense	(113)	(113)	(86)
Other, net		1	1
Total investment and other income	32	34	57
Income (loss) before income taxes	(272)	82	404
Income tax expense (benefit)	(287)	33	157
Net income	15	49	247
Less: Net income attributable to noncontrolling interests, net of tax	3	1	6
Net income attributable to U.S. Cellular shareholders	$ 12	$ 48	$ 241
Basic weighted average shares outstanding	85	85	84
Basic earnings per share attributable to U.S. Cellular shareholders	$ 0.14	$ 0.56	$ 2.86
Diluted weighted average shares outstanding	86	85	85
Diluted earnings per share attributable to U.S. Cellular shareholders	$ 0.14	$ 0.56	$ 2.84

Consolidated Statement Of Oper3

Consolidated Statement Of Operations Parenthetical - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating expenses
Selling, general and administrative, charges from affiliates	$ 85	$ 94	$ 96

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income	$ 15	$ 49	$ 247
Add (deduct) adjustments to reconcile net income to net cash flows from operating activities
Depreciation, amortization and accretion	615	618	607
Bad debts expense	89	96	106
Stock-based compensation expense	30	26	25
Deferred income taxes, net	(365)	6	55
Equity in earnings of unconsolidated entities	(137)	(140)	(140)
Distributions from unconsolidated entities	136	93	60
Loss on impairment of goodwill	370	0	0
(Gain) loss on asset disposals, net	17	22	16
(Gain) loss on sale of business and other exit costs, net	(1)		(114)
(Gain) loss on license sales and exchanges, net	(22)	(19)	(147)
Noncash interest	2	2	2
Other operating activities	0	(2)	0
Changes in assets and liabilities from operations
Accounts receivable	(68)	(23)	(96)
Equipment installment plans receivable	(261)	(246)	(134)
Inventory		8	118
Accounts payable	(14)	48	5
Customer deposits and deferred revenues	(3)	(54)	(37)
Accrued taxes	26	40	34
Accrued interest		(2)	4
Other assets and liabilities	40	(21)	(56)
Net cash provided by operating activities	469	501	555
Cash flows from investing activities
Cash paid for additions to property, plant and equipment	(465)	(443)	(581)
Cash paid for licenses	(189)	(53)	(286)
Cash paid for investments	(50)	0	0
Cash received from divestitures and exchanges	21	21	317
Federal Communications Commission deposit	0	(143)	0
Net cash used in investing activities	(683)	(618)	(550)
Cash flows from financing activities
Issuance of long-term debt	0	0	525
Repayment of long-term debt	(14)	(11)
Common shares reissued for benefit plans, net of tax payments	1	6	2
Common shares repurchased	0	(5)	(6)
Payment of debt issuance costs	(2)	(2)	(13)
Acquisition of assets in common control transaction	0	0	(2)
Distributions to noncontrolling interests	(4)	(1)	(6)
Payments to acquire additional interest in subsidiaries	0	0	(2)
Other financing activities	(1)	1	(1)
Net cash provided by (used in) financing activities	(20)	(12)	497
Net increase (decrease) in cash, cash equivalents and restricted cash	(234)	(129)	502
Cash, cash equivalents and restricted cash
Beginning of period	586	715	213
End of period	$ 352	$ 586	$ 715

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents		$ 352	$ 586
Short-term investments		50	0
Accounts receivable
Customers and agents, less allowances of $55 and $51, respectively		775	658
Roaming		26	16
Affiliated		1	2
Other, less allowances of $1 and $1, respectively		41	51
Inventory, net		138	138
Prepaid expenses		79	84
Other current assets		21	23
Total current assets		1,483	1,558
Assets held for sale		10	8
Licenses		2,223	1,886
Goodwill		0	370
Investments in unconsolidated entities		415	413
Property, plant and equipment
In service and under construction		7,628	7,712
Less: Accumulated depreciation and amortization		5,308	5,242
Property, plant and equipment, net		2,320	2,470
Other assets and deferred charges		390	405
Total assets	[1]	6,841	7,110
Current liabilities
Current portion of long-term debt		18	11
Accounts payable
Affiliated		8	12
Trade		302	309
Customer deposits and deferred revenues		185	190
Accrued taxes		56	39
Accrued compensation		74	73
Other current liabilities		90	84
Total current liabilities		733	718
Deferred liabilities and credits
Deferred income tax liability, net		461	826
Other deferred liabilities and credits		337	302
Long-term debt, net		1,622	1,618
Commitments and contingencies
Noncontrolling interests with redemption features		1	1
U.S. Cellular shareholders' equity
Series A Common and Common Shares Authorized 190 shares (50 Series A Common and 140 Common Shares) Issued 88 shares (33 Series A Common and 55 Common Shares) Outstanding 85 shares (33 Series A Common and 52 Common Shares) Par Value ($1.00 per share)($33 Series A Common and $55 Common Shares)		88	88
Additional paid-in capital		1,552	1,522
Treasury shares, at cost, 3 Common Shares		(120)	(136)
Retained earnings		2,157	2,160
Total U.S. Cellular shareholders' equity		3,677	3,634
Noncontrolling interests		10	11
Total equity		3,687	3,645
Total liabilities and equity	[1]	$ 6,841	$ 7,110
[1]	The consolidated total assets as of December 31, 2017 and 2016 include assets held by consolidated VIEs of $785 million and $827 million, respectively, which are not available to be used to settle the obligations of U.S. Cellular. The consolidated total liabilities as of December 31, 2017 and 2016 include certain liabilities of consolidated VIEs of $24 million and $19 million, respectively, for which the creditors of the VIEs have no recourse to the general credit of U.S. Cellular. See Note 13 — Variable Interest Entities for additional information.

Consolidated Balance Sheet Pare

Consolidated Balance Sheet Parenthetical - USD ($) shares in Millions, $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accounts receivable
Customers and agents allowances	$ 55	$ 51
Other allowances	$ 1	$ 1
U.S. Cellular shareholders' equity
Authorized shares	190	190
Issued shares	88	88
Outstanding shares	85	85
Par value	$ 88	$ 88
Treasury shares	3	3
Variable Interest Entities VIE's
Total VIE assets that can be used to settle only the VIEs' obligations	$ 785	$ 827
Total VIE liabilities for which creditors have no recourse	$ 24	$ 19
Series A Common Shares
U.S. Cellular shareholders' equity
Authorized shares	50	50
Issued shares	33	33
Outstanding shares	33	33
Par value per share	$ 1	$ 1
Par value	$ 33	$ 33
Common Shares
U.S. Cellular shareholders' equity
Authorized shares	140	140
Issued shares	55	55
Outstanding shares	52	52
Par value per share	$ 1	$ 1
Par value	$ 55	$ 55
Treasury shares	3	3

Consolidated Statement of Chang

Consolidated Statement of Changes in Equity - USD ($) $ in Millions	Total	Series A Common and Common shares	Additional paid-in capital	Treasury shares	Retained earnings	Total U.S. Cellular shareholders' equity	Noncontrolling interests
Beginning balance at Dec. 31, 2014	$ 3,313	$ 88	$ 1,473	$ (169)	$ 1,910	$ 3,302	$ 11
Net income attributable to U.S. Cellular shareholders	241				241	241
Repurchase of Common Shares	(6)			(6)		(6)
Incentive and compensation plans	2			18	(16)	2
Stock-based compensation awards	24		24			24
Tax windfall (shortfall) from stock awards	(1)		(1)			(1)
Distributions to noncontrolling interests	(1)						(1)
Acquisition of assets in common control transaction	(1)		1		(2)	(1)
Ending balance at Dec. 31, 2015	3,571	88	1,497	(157)	2,133	3,561	10
Net income attributable to U.S. Cellular shareholders	48				48	48
Net income attributable to noncontrolling interests classified as equity	2						2
Repurchase of Common Shares	(5)			(5)		(5)
Incentive and compensation plans	5			26	(21)	5
Stock-based compensation awards	25		25			25
Distributions to noncontrolling interests	(1)						(1)
Ending balance at Dec. 31, 2016	3,645	88	1,522	(136)	2,160	3,634	11
Net income attributable to U.S. Cellular shareholders	12				12	12
Net income attributable to noncontrolling interests classified as equity	3						3
Incentive and compensation plans	1			16	(15)	1
Stock-based compensation awards	30		30			30
Distributions to noncontrolling interests	(4)						(4)
Ending balance at Dec. 31, 2017	$ 3,687	$ 88	$ 1,552	$ (120)	$ 2,157	$ 3,677	$ 10

Summary of Significant Accounti

Summary of Significant Accounting Policies and Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies and Recent Accounting Pronouncements	N ote 1 Summary of Significant Accounting Policies and Recent Accounting Pronouncements United States Cellular Corporation (U.S. Cellular), a Delaware Corporation, is an 83% -owned subsidiary of Telephone and Data Systems, Inc. (TDS). Nature of Operations U.S. Cellular owns, operates and invests in wireless systems throughout the United States. As of December 31, 2017 , U.S. Cellular served customers with 5.1 million total connections. U.S. Cellular has one reportable segment. Principles of Consolidation The accounting policies of U.S. Cellular conform to accounting principles generally accepted in the United States of America (GAAP) as set forth in the Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC). Unless otherwise specified, references to accounting provisions and GAAP in these notes refer to the requirements of the FASB ASC. The consolidated financial statements include the accounts of U.S. Cellular, subsidiaries in which it has a controlling financial interest, general partnerships in which U.S. Cellular has a majority partnership interest and certain entities in which U.S. Cellular has a variable interest that requires consolidation under GAAP. See Note 13 — Variable Interest Entities for additional information relating to U.S. Cellular’s VIEs. All material intercompany accounts and transactions have been eliminated. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect (a) the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and (b) the reported amounts of revenues and expenses during the reported period. Actual results could differ from those estimates. Significant estimates are involved in accounting for goodwill and indefinite-lived intangible assets, income taxes and equipment installment plans. Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents include cash and highly liquid investments with original maturities of three months or less. Cash and cash equivalents subject to contractual restrictions are classified as restricted cash. On December 31, 2017, U.S. Cellular early adopted the provisions of Accounting Standards Update 2016-18, Statement of Cash Flows: Restricted Cash (ASU 2016-18) on a retrospective basis which requires that restricted cash be presented with cash and cash equivalents in the statement of cash flows. U.S. Cellular had less than $1 million of restricted cash as of December 31, 2017 , and had no restricted cash balances as of December 31, 2016 or 2015 . Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable consist primarily of amounts owed by customers for wireless services and equipment sales, including sales of certain devices under equipment installment plans, by agents for sales of equipment to them and by other wireless carriers whose customers have used U.S. Cellular’s wireless systems. The allowance for doubtful accounts is the best estimate of the amount of probable credit losses related to existing billed and unbilled accounts receivable. The allowance is estimated based on historical experience, account aging and other factors that could affect collectability. Accounts receivable balances are reviewed on either an aggregate or individual basis for collectability depending on the type of receivable. When it is probable that an account balance will not be collected, the account balance is charged against the allowance for doubtful accounts. U.S. Cellular does not have any off-balance sheet credit exposure related to its customers. Inventory Inventory consists primarily of wireless devices stated at the lower of cost or net realizable value. Cost is determined using the first-in, first-out method. Net realizable value is determined by reference to the stand-alone selling price. Licenses Licenses consist of direct and incremental costs incurred in acquiring Federal Communications Commission (FCC) licenses to provide wireless service. U.S. Cellular has determined that wireless licenses are indefinite-lived intangible assets and, therefore, not subject to amortization based on the following factors: Radio spectrum is not a depleting asset. The ability to use radio spectrum is not limited to any one technology. U.S. Cellular and its consolidated subsidiaries are licensed to use radio spectrum through the FCC licensing process, which enables licensees to utilize specified portions of the spectrum for the provision of wireless service. U.S. Cellular and its consolidated subsidiaries are required to renew their FCC licenses every ten years or, in some cases, every fifteen years. To date, all of U.S. Cellular’s license renewal applications have been granted by the FCC. Generally, license renewal applications filed by licensees otherwise in compliance with FCC regulations are routinely granted. If, however, a license renewal application is challenged either by a competing applicant for the license or by a petition to deny the renewal application, the license will be renewed if the licensee can demonstrate its entitlement to a “renewal expectancy.” Licensees are entitled to such an expectancy if they can demonstrate to the FCC that they have provided “substantial service” during their license term and have “substantially complied” with FCC rules and policies. U.S. Cellular believes that it is probable that its future license renewal applications will be granted. U.S. Cellular performs its annual impairment assessment of Licenses as of November 1 of each year or more frequently if there are events or circumstances that cause U.S. Cellular to believe the carrying value of Licenses exceeds their fair value on a more likely than not basis. For purposes of its 2017 and 2016 impairment testing of Licenses, U.S. Cellular separated its FCC licenses into eight units of accounting. The eight units of accounting consisted of one unit of accounting for developed operating market licenses (built licenses) and seven geographic non-operating market licenses (unbuilt licenses). U.S. Cellular performed a quantitative impairment assessment in 2017 and a qualitative impairment assessment in 2016 to determine whether it was more likely than not that the fair value of the built and unbuilt licenses exceed their carrying value. Based on the impairment assessments performed, U.S. Cellular did not have an impairment of its Licenses in 2017 or 2016 . See Note 7 — Intangible Assets for additional details related to Licenses. Goodwill U.S. Cellular early adopted Accounting Standards Update 2017-04, Intangibles – Goodwill and Other: Simplifying the Test for Goodwill Impairment (ASU 2017-04), in the third quarter of 2017 and applied the guidance to interim goodwill impairment tests completed in 2017. ASU 2017-04 eliminated Step 2 of the goodwill impairment test. Goodwill impairment loss will be measured as the amount by which a reporting unit’s carrying amount exceeds its fair value. The loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. U.S. Cellular had Goodwill as a result of its acquisitions of wireless businesses. Such Goodwill represents the excess of the total purchase price over the fair value of net assets acquired in these transactions. For purposes of conducting its impairment tests, U.S. Cellular identified one reporting unit. A discounted cash flow approach was used to value the reporting unit for purposes of the Goodwill impairment review. U.S. Cellular performs its annual impairment test as of November 1. However, in the third quarter of 2017, management identified a triggering event and performed an interim impairment test of Goodwill, which resulted in the recognition of an impairment loss of $370 million. U.S. Cellular did not have an impairment of its Goodwill in 2016 . See Note 7 — Intangible Assets for additional details related to Goodwill. Investments in Unconsolidated Entities For its equity method investments for which financial information is readily available, U.S. Cellular records its equity in the earnings of the entity in the current period. For its equity method investments for which financial information is not readily available, U.S. Cellular records its equity in the earnings of the entity on a one quarter lag basis. Property, Plant and Equipment U.S. Cellular’s Property, plant and equipment is stated at the original cost of construction or purchase including capitalized costs of certain taxes, payroll-related expenses, interest and estimated costs to remove the assets. Expenditures that enhance the productive capacity of assets in service or extend their useful lives are capitalized and depreciated. Expenditures for maintenance and repairs of assets in service are charged to System operations expense or Selling, general and administrative expense, as applicable. Retirements and disposals of assets are recorded by removing the original cost of the asset (along with the related accumulated depreciation) from plant in service and charging it, together with net removal costs (removal costs less an applicable accrued asset retirement obligation and salvage value realized), to (Gain) loss on asset disposals, net. U.S. Cellular capitalizes certain costs of developing new information systems. Software licenses are accounted for as the acquisition of an intangible asset and the incurrence of a liability to the extent that the license fees are not fully paid at acquisition. Depreciation and Amortization Depreciation is provided using the straight-line method over the estimated useful life of the related asset. U.S. Cellular depreciates leasehold improvement assets associated with leased properties over periods ranging from one to thirty years; such periods approximate the shorter of the assets’ economic lives or the specific lease terms. Useful lives of specific assets are reviewed throughout the year to determine if changes in technology or other business changes would warrant accelerating the depreciation of those specific assets. There were no material changes to useful lives of property, plant and equipment in 2017 , 2016 or 2015 . See Note 9 — Property, Plant and Equipment for additional details related to useful lives. Impairment of Long-Lived Assets U.S. Cellular reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the assets might be impaired. U.S. Cellular has one asset group for purposes of assessing property, plant and equipment for impairment based on the fact that the individual operating markets are reliant on centrally operated data centers, mobile telephone switching offices and a network operations center. U.S. Cellular operates a single integrated national wireless network. The cash flows generated by this single interdependent network represent the lowest level for which identifiable cash flows are largely independent of the cash flows of other groups of assets and liabilities. In connection with the interim goodwill impairment test in the third quarter of 2017, conditions existed that indicated U.S. Cellular’s long-lived asset group might not be recoverable. As a result, the company performed a long-lived asset recoverability assessment related to the U.S. Cellular asset group and determined that no impairment of the long-lived asset group existed. Agent Liabilities U.S. Cellular has relationships with agents, which are independent businesses that obtain customers for U.S. Cellular. At December 31, 2017 and 2016 , U.S. Cellular had accrued $ 61 million and $ 57 million, respectively, for amounts due to agents. These amounts are included in Other current liabilities in the Consolidated Balance Sheet. Debt Issuance Costs Debt issuance costs include underwriters’ and legal fees and other charges related to issuing various borrowing instruments and other long-term agreements, and are amortized over the respective term of each instrument. U.S. Cellular presents certain debt issuance costs in the balance sheet as an offset to the related debt obligation. Debt issuance costs related to U.S. Cellular’s revolving credit facility and receivables securitization facility are recorded in Other assets and deferred charges in the Consolidated Balance Sheet. Asset Retirement Obligations U.S. Cellular accounts for asset retirement obligations by recording the fair value of a liability for legal obligations associated with an asset retirement in the period in which the obligations are incurred. At the time the liability is incurred, U.S. Cellular records a liability equal to the net present value of the estimated cost of the asset retirement obligation and increases the carrying amount of the related long-lived asset by an equal amount. Until the obligation is fulfilled, U.S. Cellular updates its estimates relating to cash flows required and timing of settlement. U.S. Cellular records the present value of the changes in the future value as an increase or decrease to the liability and the related carrying amount of the long-lived asset. The liability is accreted to future value over a period ending with the estimated settlement date of the respective asset retirement obligation. The carrying amount of the long-lived asset is depreciated over the useful life of the related asset. Upon settlement of the obligation, any difference between the cost to retire the asset and the recorded liability is recognized in the Consolidated Statement of Operations. Treasury Shares Common Shares repurchased by U.S. Cellular are recorded at cost as treasury shares and result in a reduction of equity. When treasury shares are reissued, U.S. Cellular determines the cost using the first-in, first-out cost method. The difference between the cost of the treasury shares and reissuance price is included in Additional paid-in capital or Retained earnings. Revenue Recognition Revenues related to services are recognized as services are rendered. Revenues billed in advance or in arrears of the services being provided are estimated and deferred or accrued, as appropriate. Revenues from sales of equipment and accessories are recognized when U.S. Cellular no longer has any requirements to perform, when title has passed and when the products are accepted by the customer. Multiple Deliverable Arrangements U.S. Cellular sells multiple element service and equipment offerings. In these instances, revenues are allocated using the relative selling price method. Under this method, arrangement consideration is allocated to each element on the basis of its relative selling price. Revenue recognized for the delivered items is limited to the amount due from the customer that is not contingent upon the delivery of additional products or services. Loyalty Reward Program In March 2015, U.S. Cellular announced that it would discontinue its loyalty reward program effective September 1, 2015. All unredeemed reward points expired at that time and the deferred revenue balance of $ 58 million related to such expired points was recognized as service revenues. U.S. Cellular followed the deferred revenue method of accounting for its loyalty reward program. Under this method, revenue allocated to loyalty reward points was deferred. The amount allocated to the loyalty points was based on the estimated retail price of the services and products for which points were redeemable divided by the number of loyalty points required to receive such services and products. This was calculated on a weighted average basis and required U.S. Cellular to estimate the percentage of loyalty points that would be redeemed for each product or service. Revenue was recognized at the time of customer redemption or when such points were depleted via an account maintenance charge. U.S. Cellular employed the proportional model to recognize revenues associated with breakage. Under the proportional model, U.S. Cellular allocated a portion of the estimated future breakage to each redemption and recorded revenue proportionally. Equipment Installment Plans Equipment revenue under equipment installment plan contracts is recognized at the time the device is delivered to the end-user customer for the selling price of the device, net of any deferred imputed interest or trade-in right, if applicable. Imputed interest is reflected as a reduction to the receivable balance and recognized over the duration of the plan as Service revenues. Incentives Discounts and incentives that are deemed cash are recognized as a reduction of Operating revenues concurrently with the associated revenue. U.S. Cellular issues rebates to its agents and end customers. These incentives are recognized as a reduction to revenue at the time the wireless device sale to the customer occurs. The total potential rebates and incentives are reduced by U.S. Cellular’s estimate of rebates that will not be redeemed by customers based on historical experience of such redemptions. From time to time, U.S. Cellular may offer certain promotions to incentivize customers to switch to, or to purchase additional services from, U.S. Cellular. Under these types of promotions, an eligible customer may receive an incentive in the form of a discount off additional services purchased shown as a rebate or credit to the customer’s monthly bill. U.S. Cellular accounts for the future discounts at the time of the initial transaction by allocating and deferring a portion of equipment revenue based on the relative proportion of the future discounts in comparison to the aggregate initial purchase plus the minimum future purchases required to receive the discounts. The deferred revenue will be recognized as service revenue in future periods. Activation Fees U.S. Cellular has charged its end customers activation fees in connection with the sale of certain services and equipment. Device activation fees charged at both agent locations and U.S. Cellular company-owned retail stores in connection with equipment installment plan device transactions are deferred and recognized over a period that corresponds with the equipment upgrade eligibility date based on the contract terms. Device activation fees charged at agent locations in connection with subsidized device sales are deferred and recognized over a period that corresponds with the length of the customer’s service contract. Device activation fees charged at U.S. Cellular company-owned retail stores in connection with subsidized device sales are recognized at the time the device is delivered to the customer. Amounts Collected from Customers and Remitted to Governmental Authorities U.S. Cellular records amounts collected from customers and remitted to governmental authorities on a net basis within a tax liability account if the tax is assessed upon the customer and U.S. Cellular merely acts as an agent in collecting the tax on behalf of the imposing governmental authority. If the tax is assessed upon U.S. Cellular, then amounts collected from customers as recovery of the tax are recorded in Service revenues and amounts remitted to governmental authorities are recorded in Selling, general and administrative expenses in the Consolidated Statement of Operations. The amounts recorded gross in revenues that are billed to customers and remitted to governmental authorities totaled $ 58 million, $ 64 million and $ 77 million for 2017 , 2016 and 2015 , respectively. Eligible Telecommunications Carrier (ETC) Revenues Telecommunications companies may be designated by states, or in some cases by the FCC, as an ETC to receive support payments from the Universal Service Fund if they provide specified services in “high cost” areas. ETC revenues recognized in the reporting period represent the amounts which U.S. Cellular is entitled to receive for such period, as determined and approved in connection with U.S. Cellular’s designation as an ETC in various states. Advertising Costs U.S. Cellular expenses advertising costs as incurred. Advertising costs totaled $ 211 million, $ 245 million and $ 231 million in 2017 , 2016 and 2015 , respectively. Income Taxes U.S. Cellular is included in a consolidated federal income tax return with other members of the TDS consolidated group. For financial statement purposes, U.S. Cellular and its subsidiaries calculate their income, income taxes and credits as if they comprised a separate affiliated group. Under a tax allocation agreement between TDS and U.S. Cellular, U.S. Cellular remits its applicable income tax payments to TDS. U.S. Cellular had a tax payable balance with TDS of $ 23 million and $ 8 million as of December 31, 2017 and 2016 , respectively . Deferred taxes are computed using the liability method, whereby deferred tax assets are recognized for future deductible temporary differences and operating loss carryforwards, and deferred tax liabilities are recognized for future taxable temporary differences. Both deferred tax assets and liabilities are measured using the tax rates anticipated to be in effect when the temporary differences reverse. Temporary differences are the differences between the reported amounts of assets and liabilities and their tax bases. Deferred tax assets and liabilities are adjusted for the effects of changes in tax laws and rates on the date of enactment. Deferred tax assets are reduced by a valuation allowance when it is more likely than not that some portion or all of the deferred tax assets will not be realized. U.S. Cellular evaluates income tax uncertainties, assesses the probability of the ultimate settlement with the applicable taxing authority and records an amount based on that assessment. Deferred taxes are reported as a net non-current asset or liability by jurisdiction. Any corresponding valuation allowance to reduce the amount of deferred tax assets is also recorded as non-current. Stock-Based Compensation and Other Plans U.S. Cellular has established a long-term incentive plan and a non-employee director compensation plan. These plans are considered compensatory plans and, therefore, recognition of compensation cost for grants made under these plans is required. U.S. Cellular recognizes stock compensation expense based upon the fair value of the specific awards granted using established valuation methodologies. The amount of stock compensation cost recognized on either a straight-line basis or graded attribution method is based on the portion of the award that is expected to vest over the requisite service period, which generally represents the vesting period. Stock-based compensation cost recognized has been reduced for estimated forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. See Note 16 — Stock-Based Compensation for additional information. Defined Contribution Plans U.S. Cellular participates in a qualified noncontributory defined contribution pension plan sponsored by TDS; such plan provides pension benefits for the employees of U.S. Cellular and its subsidiaries. Under this plan, pension benefits and costs are calculated separately for each participant and are funded currently. Pension costs were $ 11 million in 2017 , 2016 and 2015 . U.S. Cellular also participates in a defined contribution retirement savings plan (401(k) plan) sponsored by TDS. Total costs incurred for U.S. Cellular’s contributions to the 401(k) plan were $ 16 million, $ 16 million and $ 15 million in 2017 , 2016 and 2015 , respectively. Recently Issued Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update 2014-09, Revenue from Contracts with Customers (ASU 2014-09) and has since amended the standard with Accounting Standards Update 2015-14, Revenue from Contracts with Customers: Deferral of the Effective Date , Accounting Standards Update 2016-08, Revenue from Contracts with Customers: Principal versus Agent Considerations (Reporting Revenue Gross versus Net) , Accounting Standards Update 2016-10, Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing , Accounting Standards Update 2016-12, Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients , and Accounting Standards Update 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers . These standards replace existing revenue recognition rules with a single comprehensive model to use in accounting for revenue arising from contracts with customers. U.S. Cellular will adopt ASU 2014-09, as amended, on January 1, 2018, under the modified retrospective transition method whereby a cumulative effect adjustment to retained earnings will be recognized upon adoption and the guidance is applied prospectively. U.S. Cellular has implemented new systems, processes and controls to adopt ASU 2014-09, as amended. ASU 2014-09, as amended, impacts U.S. Cellular’s revenue recognition related to the allocation of contract revenues between various services and equipment, and the timing of when those revenues are recognized. In addition, ASU 2014-09, as amended, requires deferral of incremental contract acquisition and fulfillment costs and subsequent expense recognition over the contract period or expected customer life. Upon adoption, the cumulative effect adjustment will include the establishment of contract asset and contract liability accounts with a corresponding adjustment to retained earnings to reflect the reallocation of revenues between service and equipment performance obligations for which control is transferred to customers in different periods. Reallocation impacts generally arise when bundle discounts are provided in a contract arrangement that includes equipment and service performance obligations. In these cases, the revenue will be reallocated according to the relative stand-alone selling prices of the performance obligations included in the bundle and this may be different than how the revenue is billed to the customer and recognized under current guidance. In addition, contract cost assets will be established to reflect costs that will be deferred as incremental contract acquisition costs. Incremental contract acquisition costs generally relate to commissions paid to sales associates. The cumulative effect of adoption of the new standard will be to increase Retained earnings as of January 1, 2018, by approximately $ 160 million. Based on currently available information, U.S. Cellular estimates that the new standard will not have a significant impact on operating income in 2018. In January 2016, the FASB issued Accounting Standards Update 2016-01, Financial Instruments – Overall: Recognition and Measurement of Financial Assets and Financial Liabilities (ASU 2016-01). This ASU introduces changes to current accounting for equity investments and financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. U.S. Cellular is required to adopt ASU 2016-01 on January 1, 2018, using the modified retrospective approach. The adoption of ASU 2016-01 is not expected to have a significant impact on U.S. Cellular’s financial position or results of operations. In February 2016, the FASB issued Accounting Standards Update 2016-02, Leases (ASU 2016-02). ASU 2016-02 requires lessees to record a right-of-use asset and lease liability for almost all leases. This ASU does not substantially impact the lessor accounting model. However, some changes to the lessor accounting guidance were made to align with lessee accounting changes within Accounting Standards Codification (ASC) 842, Leases and certain key aspects of ASC 606, Revenue from Contracts with Customers. Early adoption is permitted; however, U.S. Cellular plans to adopt ASU 2016-02 on a modified retrospective basis when required on January 1, 2019. In January 2018, the FASB issued Accounting Standards Update 2018-01, Leases (ASU 2018-01), which permits an entity to elect an optional transition practical expedient to not evaluate land easements that exist or expired before the entities adoption of ASU 2016-02. U.S. Cellular plans to adopt ASU 2018-01 in conjunction with its adoption of ASU 2016-02. U.S. Cellular is evaluating the full effect that adoption of ASU 2016-02 and ASU 2018-01 will have on its financial condition, results of operations and disclosures. Upon adoption, U.S. Cellular expects a substantial increase to assets and liabilities on its balance sheet and is in the process of implementing a new lease management and accounting system to assist in the application of the new standard. In March 2016, the FASB issued Accounting Standards Update 2016-04, Liabilities – Extinguishments of Liabilities: Recognition of Breakage from Certain Prepaid Stored-Value Products (ASU 2016-04). ASU 2016-04 requires companies that sell prepaid stored-value products redeemable for goods, services or cash at third-party merchants to recognize breakage (i.e., the value that is ultimately not redeemed by the consumer) in a way that is consistent with how it will be recognized under the new revenue recognition standard. U.S. Cellular is required to adopt ASU 2016-04 on January 1, 2018, retrospectively. The adoption of ASU 2016-04 is not expected to have a significant impact on U.S. Cellular’s financial position or results of operations. In June 2016, the FASB issued Accounting Standards Update 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments (ASU 2016-13). ASU 2016-13 requires entities to use a new forward-looking, expected loss model to estimate credit losses. It also requires additional disclosure relating to the credit quality of trade and other receivables, including information relating to management’s estimate of credit allowances. U.S. Cellular is required to adopt ASU 2016-13 on January 1, 2020, using the modified retrospective approach. Early adoption is permitted as of January 1, 2019. U.S. Cellular is evaluating the effects that adoption of ASU 2016-13 will have on its financial position, results of operations and disclosures. In October 2016, the FASB issued Accounting Standards Update 2016-16, Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory (ASU 2016-16). ASU 2016-16 impacts the accounting for the income tax consequences of intra-entity transfers of assets other than inventory when the transfer occurs between entities in different tax jurisdictions. U.S. Cellular is required to adopt ASU 2016-16 on January 1, 2018, using the modified retrospective approach. The adoption of ASU 2016-16 is not expected to have a significant impact on U.S. Cellular’s financial position or results of operations. In February 2017, the FASB issued Accounting Standards Update 2017-05, Other Income – Gains and Losses from the Derecognition of Nonfinancial Assets: Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets (ASU 2017-05). ASU 2017-05 clarifies how entities account for the derecognition of a nonfinancial asset and adds guidance for partial sales of nonfinancial assets. U.S. Cellular is required to adopt ASU 2017-05 on January 1, 2018, either retrospectively or using the modified retrospective approach. The adoption of ASU 2017-05 is not expected to have a significant impact on U.S. Cellular’s financial position or results of operations. In May 2017, the FASB issued Accounting Standards Update 2017-09, Compensation – Stock Compensation (ASU 2017-09). ASU 2017-09 clarifies when changes to the terms or conditions of share-based payment awards must be accounted for as modifications. U.S. Cellular is required to adopt ASU 2017-09 prospectively on January 1, 2018. The adoption of ASU 2017-09 is not expected to have a significant impact on U.S. Cellular’s financial position or results of operations. In July 2017, the FASB issued Accounting Standards Update 2017-11, Earnings Per Share, Distinguishing Liabilities from Equity, Derivatives and Hedging: I. Accounting for Certain Financial Instruments with Down Round Features, II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (ASU 2017-11). The amendments in Part I of ASU 2017-11 that relate to liability or equity classification of financial instruments (or embedded features) affect all entities that issue financial instruments (for example, warrants or convertible instruments) that include down round features. The amendments

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 2 Fair Value Measurements As of December 31, 2017 and 2016 , U.S. Cellular did not have any material financial or nonfinancial assets or liabilities that were required to be recorded at fair value in its Consolidated Balance Sheet in accordance with GAAP. The provisions of GAAP establish a fair value hierarchy that contains three levels for inputs used in fair value measurements. Level 1 inputs include quoted market prices for identical assets or liabilities in active markets. Level 2 inputs include quoted market prices for similar assets and liabilities in active markets or quoted market prices for identical assets and liabilities in inactive markets. Level 3 inputs are unobservable. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. A financial instrument’s level within the fair value hierarchy is not representative of its expected performance or its overall risk profile and, therefore, Level 3 assets are not necessarily higher risk than Level 2 assets or Level 1 assets. U.S. Cellular has applied the provisions of fair value accounting for purposes of computing the fair value of financial instruments for disclosure purposes as displayed below. Level within the Fair Value Hierarchy December 31, 2017 December 31, 2016 Book Value Fair Value Book Value Fair Value (Dollars in millions) Cash and cash equivalents 1 $ 352 $ 352 $ 586 $ 586 Short-term investments 1 50 50 – – Long-term debt Retail 2 917 939 917 929 Institutional 2 534 522 533 532 Other 2 191 191 203 203 The fair value of Cash and cash equivalents and Short-term investments approximate their book values due to the short-term nature of these financial instruments. Long-term debt excludes capital lease obligations, other installment arrangements, the current portion of Long-term debt and debt financing costs. The fair value of “Retail” Long-term debt was estimated using market prices for the 6.95% Senior Notes, 7.25% 2063 Senior Notes and 7.25% 2064 Senior Notes. U.S. Cellular’s “Institutional” debt consists of the 6.7% Senior Notes which are traded over the counter. U.S. Cellular’s “Other” debt consists of a senior term loan credit facility. U.S. Cellular estimated the fair value of its Institutional and Other debt through a discounted cash flow analysis using the interest rates or estimated yield to maturity for each borrowing, which ranged from 4.74% to 7.13% and 3.78% to 6.93% at December 31, 2017 and 2016 , respectively.

Equipment Installment Plans

Equipment Installment Plans	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Equipment Installment Plans	Note 3 Equipment Installment Plans U.S. Cellular sells devices to customers under equipment installment contracts over a specified time period. For certain equipment installment plans, after a specified period of time or amount of payments, the customer may have the right to upgrade to a new device and have the remaining unpaid equipment installment contract balance waived, subject to certain conditions, including trading in the original device in good working condition and signing a new equipment installment contract. U.S. Cellular values this trade-in right as a guarantee liability. The guarantee liability is initially measured at fair value and is determined based on assumptions including the probability and timing of the customer upgrading to a new device and the fair value of the device being traded-in at the time of trade-in. When a customer exercises the trade-in option, both the outstanding receivable and guarantee liability balances related to the respective device are reduced to zero, and the value of the used device that is received in the transaction is recognized as inventory. If the customer does not exercise the trade-in option at the time of eligibility, U.S. Cellular begins amortizing the liability and records this amortization as additional equipment revenue. As of December 31, 2017 and 2016 , the guarantee liability related to these plans was $ 15 million and $ 33 million, respectively, and is reflected in Customer deposits and deferred revenues in the Consolidated Balance Sheet. U.S. Cellular equipment installment plans do not provide for explicit interest charges. Because equipment installment plans have a duration of greater than twelve months, U.S. Cellular imputes interest. U.S. Cellular records imputed interest as a reduction to the related accounts receivable and recognizes it over the term of the installment agreement as a component of Service revenues. Equipment installment plan receivables had a weighted average effective imputed interest rate of 12.5% and 11.2% as of December 31, 2017 and 2016 , respectively. The following table summarizes equipment installment plan receivables as of December 31, 2017 and 2016 . December 31, 2017 2016 (Dollars in millions) Equipment installment plan receivables, gross $ 873 $ 628 Deferred interest (80) (53) Equipment installment plan receivables, net of deferred interest 793 575 Allowance for credit losses (65) (50) Equipment installment plan receivables, net $ 728 $ 525 Net balance presented in the Consolidated Balance Sheet as: Accounts receivable — Customers and agents (Current portion) $ 428 $ 345 Other assets and deferred charges (Non-current portion) 300 180 Equipment installment plan receivables, net $ 728 $ 525 U.S. Cellular uses various inputs, including internal data, information from the credit bureaus and other sources, to evaluate the credit profiles of its customers. From this evaluation, a credit class is assigned to the customer that determines the number of eligible lines, the amount of credit available, and the down payment requirement, if any. Customers assigned to credit classes requiring no down payment represent a lower risk category, whereas those assigned to credit classes requiring a down payment represent a higher risk category. The balance and aging of the equipment installment plan receivables on a gross basis by credit category were as follows: December 31, 2017 December 31, 2016 Lower Risk Higher Risk Total Lower Risk Higher Risk Total (Dollars in millions) Unbilled $ 807 $ 20 $ 827 $ 553 $ 38 $ 591 Billed — current 31 1 32 23 2 25 Billed — past due 12 2 14 10 2 12 Equipment installment plan receivables, gross $ 850 $ 23 $ 873 $ 586 $ 42 $ 628 The activity in the allowance for credit losses balance for the equipment installment plan receivables was as follows: 2017 2016 (Dollars in millions) Allowance for credit losses, beginning of year $ 50 $ 26 Bad debts expense 62 63 Write-offs, net of recoveries (47) (39) Allowance for credit losses, end of year $ 65 $ 50 U.S. Cellular recorded out-of-period adjustments in 2016 due to errors related to equipment installment plan transactions occurring in 2015 (2016 EIP adjustments). The 2016 EIP adjustments had the impact of increasing Equipment sales revenues by $ 2 million, decreasing bad debts expense, which is a component of Selling, general and administrative expense, by $ 2 million and increasing Income before income taxes by $ 4 million in 2016. Additionally, U.S. Cellular recorded out-of-period adjustments in 2015 due to errors related to equipment installment plan transactions (2015 EIP adjustments) that were attributable to 2014. The 2015 EIP adjustments had the impact of reducing Equipment sales revenues and Income before income taxes by $ 6 million in 2015. U.S. Cellular has determined that these adjustments were not material to any of the periods impacted.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Note 4 Income Taxes U.S. Cellular is included in a consolidated federal income tax return and in certain state income tax returns with other members of the TDS consolidated group. For financial statement purposes, U.S. Cellular and its subsidiaries compute their income tax expense as if they comprised a separate affiliated group and were not included in the TDS consolidated group. U.S. Cellular’s current income taxes balances at December 31, 2017 and 2016 , were as follows: December 31, 2017 2016 (Dollars in millions) Federal income taxes payable $ 22 $ 8 Net state income taxes payable 1 – Income tax expense (benefit) is summarized as follows: Year Ended December 31, 2017 2016 2015 (Dollars in millions) Current Federal $ 68 $ 29 $ 97 State 10 (2) 5 Deferred Federal (354) 1 48 State (11) 5 7 Total income tax expense (benefit) $ (287) $ 33 $ 157 In December 2017, the Tax Act was signed into law. U.S. Cellular adjusts for the effects of changes in tax laws and rates in the period of enactment. The major provisions of the Tax Act impacting U.S. Cellular are the reduction of the U.S. federal corporate tax rate from 35% to 21% and the bonus depreciation deduction allowing for full expensing of qualified property additions. The disclosed amounts within include provisional estimates, pursuant to SEC Staff Accounting Bulletin No. 118, for current and deferred taxes related to tax depreciation of fixed assets. For property acquired and placed in service after September 27, 2017, the Tax Act provides for full expensing if such property was not subject to a written binding agreement in existence as of September 27, 2017. As of December 31, 2017, U.S. Cellular has not completed a full analysis of all contracts and agreements related to fixed assets placed in service during 2017, but was able to record a reasonable estimate of the effects of these changes based on capital expenditures made during 2017. U.S. Cellular expects any final adjustments to the provisional amounts to be recorded by the third quarter of 2018, which could be material to U.S. Cellular’s financial statements. The accounting for all other applicable provisions of the Tax Act was performed based on U.S. Cellular’s current interpretation of the provisions of the law as enacted as of December 31, 2017. A reconciliation of U.S. Cellular’s income tax expense computed at the statutory rate to the reported income tax expense, and the statutory federal income tax expense rate to U.S. Cellular’s effective income tax expense rate is as follows: Year Ended December 31, 2017 2016 2015 Amount Rate Amount Rate Amount Rate (Dollars in millions) Statutory federal income tax expense and rate $ (95) 35.0 % $ 29 35.0 % $ 141 35.0 % State income taxes, net of federal benefit 1 (4) 1.4 3 3.6 8 2.1 Effect of noncontrolling interests (2) 0.8 (1) (1.1) 3 0.6 Federal income tax rate change 2 (254) 93.3 – – – – Goodwill impairment 3 71 (26.2) – – – – Other differences, net (3) 1.2 2 2.2 5 1.0 Total income tax expense (benefit) and rate $ (287) 105.5 % $ 33 39.7 % $ 157 38.7 % 1 State income taxes, net of federal benefit, include changes in unrecognized tax benefits as well as adjustments to the valuation allowance. 2 Federal income tax rate change due to the Tax Act reducing the federal income tax rate from 35% to 21% and a corresponding reduction to the deferred tax liability. The amount is slightly different from the total impact of the federal tax rate change because the rate change also impacts the amount of State income taxes, net of federal benefit. 3 Goodwill impairment reflects an adjustment to increase income tax expense by $71 million related to a portion of the impaired goodwill that is not amortizable for income tax purposes. See Note 7 — Intangible Assets for additional information related to the goodwill impairment. Significant components of U.S. Cellular’s deferred income tax assets and liabilities at December 31, 2017 and 2016 , were as follows: December 31, 2017 2016 (Dollars in millions) Deferred tax assets Net operating loss (NOL) carryforwards $ 103 $ 88 Stock-based compensation 20 26 Compensation and benefits - other 5 21 Deferred rent 21 21 Other 59 56 Total deferred tax assets 208 212 Less valuation allowance (77) (65) Net deferred tax assets 131 147 Deferred tax liabilities Property, plant and equipment 276 473 Licenses/intangibles 192 326 Partnership investments 123 173 Total deferred tax liabilities 591 972 Net deferred income tax liability $ 460 $ 825 Presented in the Consolidated Balance Sheet as: Deferred income tax liability, net $ 461 $ 826 Other assets and deferred charges (1) (1) Net deferred income tax liability $ 460 $ 825 At December 31, 2017 , U.S. Cellular and certain subsidiaries had $ 1,989 million of state NOL carryforwards (generating a $ 92 million deferred tax asset) available to offset future taxable income. The state NOL carryforwards expire between 2018 and 2037 . Certain subsidiaries had federal NOL carryforwards (generating an $ 11 million deferred tax asset) available to offset their future taxable income. The federal NOL carryforwards expire between 2018 and 2037 . A valuation allowance was established for certain state NOL carryforwards and federal NOL carryforwards since it is more likely than not that a portion of such carryforwards will expire before they can be utilized. A summary of U.S. Cellular’s deferred tax asset valuation allowance is as follows: 2017 2016 2015 (Dollars in millions) Balance at beginning of year $ 65 $ 55 $ 53 Charged to income tax expense 12 10 2 Balance at end of year $ 77 $ 65 $ 55 A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: 2017 2016 2015 (Dollars in millions) Unrecognized tax benefits balance at beginning of year $ 43 $ 39 $ 36 Additions for tax positions of current year 6 12 7 Additions for tax positions of prior years 1 3 1 Reductions for tax positions of prior years (1) (1) – Reductions for lapses in statutes of limitations (2) (10) (5) Unrecognized tax benefits balance at end of year $ 47 $ 43 $ 39 Unrecognized tax benefits are included in Accrued taxes and Other deferred liabilities and credits in the Consolidated Balance Sheet. If these benefits were recognized, they would have reduced income tax expense in 2017 , 2016 and 2015 by $ 38 million , $ 29 million and $ 25 million , respectively, net of the federal benefit from state income taxes. U.S. Cellular recognizes accrued interest and penalties related to unrecognized tax benefits in Income tax expense (benefit) . The amounts charged to income tax expense related to interest and penalties resulted in an expense of $ 3 million in 2017 , a benefit of $ 2 million in 2016 and an expense of $ 1 million in 2015 . Net accrued liabilities for interest and penalties were $ 19 million and $ 15 million at December 31, 2017 , and 2016 , respectively, and are included in Other deferred liabilities and credits in the Consolidated Balance Sheet. U.S. Cellular is included in TDS’ consolidated federal and certain state income tax returns. U.S. Cellular also files certain state and local income tax returns separately from TDS. With only limited exceptions, TDS is no longer subject to federal and state income tax audits for the years prior to 2013 .

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings per Share	Note 5 Earnings Per Share Basic earnings per share attributable to U.S. Cellular shareholders is computed by dividing Net income attributable to U.S. Cellular shareholders by the weighted average number of common shares outstanding during the period. Diluted earnings per share attributable to U.S. Cellular shareholders is computed by dividing Net income attributable to U.S. Cellular shareholders by the weighted average number of common shares outstanding during the period adjusted to include the effects of potentially dilutive securities. Potentially dilutive securities primarily include incremental shares issuable upon the exercise of outstanding stock options and the vesting of performance and restricted stock units. The amounts used in computing earnings per common share and the effects of potentially dilutive securities on the weighted average number of common shares were as follows: Year Ended December 31, 2017 2016 2015 (Dollars and shares in millions, except per share amounts) Net income attributable to U.S. Cellular shareholders $ 12 $ 48 $ 241 Weighted average number of shares used in basic earnings per share 85 85 84 Effect of dilutive securities 1 – 1 Weighted average number of shares used in diluted earnings per share 86 85 85 Basic earnings per share attributable to U.S. Cellular shareholders $ 0.14 $ 0.56 $ 2.86 Diluted earnings per share attributable to U.S. Cellular shareholders $ 0.14 $ 0.56 $ 2.84 Certain Common Shares issuable upon the exercise of stock options or vesting of performance and restricted stock units were not included in average diluted shares outstanding for the calculation of Diluted earnings per share attributable to U.S. Cellular shareholders because their effects were antidilutive. The number of such Common Shares excluded was 3 million shares, 3 million shares and 4 million shares for 2017 , 2016 and 2015 , respectively.

Acquisitions, Divestitures and

Acquisitions, Divestitures and Exchanges	12 Months Ended
	Dec. 31, 2017
Acquisitions, Divestitures and Exchanges [Abstract]
Acquisitions, Divestitures and Exchanges	Note 6 Acquisitions, Divestitures and Exchanges In July 2016, the FCC announced U.S. Cellular as a qualified bidder in the FCC’s forward auction of 600 MHz spectrum licenses, referred to as Auction 1002. Prior to commencement of the forward auction, U.S. Cellular made an upfront payment to the FCC of $ 143 million in June 2016 to establish its initial bidding eligibility. In April 2017, the FCC announced by way of public notice that U.S. Cellular was the winning bidder for 188 licenses for an aggregate purchase price of $ 329 million. U.S. Cellular paid the remaining $ 186 million to the FCC and was granted the licenses during the second quarter of 2017. In March 2016, U.S. Cellular entered into an agreement with a third party to transfer FCC licenses in non-operating markets and receive FCC licenses in operating markets. The agreement provided for the transfer of certain AWS and PCS spectrum licenses to U.S. Cellular in exchange for U.S. Cellular transferring certain PCS spectrum licenses with a carrying value of $ 8 million and $ 1 million of cash to the third party. This transaction closed in the fourth quarter of 2016, at which time U.S. Cellular recorded a gain of $ 3 million. In February 2016, U.S. Cellular entered into an agreement with a third party to exchange certain 700 MHz licenses for certain AWS and PCS licenses and $ 28 million of cash. This license exchange was accomplished in two closings. The first closing occurred in the second quarter of 2016 at which time U.S. Cellular received $ 13 million of cash and recorded a gain of $ 9 million. The second closing occurred in the first quarter of 2017, at which time U.S. Cellular received $15 million of cash and recorded a gain of $17 million. In February 2016, U.S. Cellular entered into an additional agreement with a third party that provided for the transfer of certain AWS spectrum licenses and $ 2 million in cash to U.S. Cellular, in exchange for U.S. Cellular transferring certain AWS, PCS and 700 MHz licenses with a carrying value of $ 7 million to the third party. This transaction closed in the third quarter of 2016, at which time U.S. Cellular recorded a gain of $ 7 million. In 2015 and 2016, U.S. Cellular entered into multiple agreements to purchase spectrum licenses located in U.S. Cellular’s existing operating markets. The aggregate purchase price for these spectrum licenses is $ 57 million, of which $ 53 million closed in 2016 and $3 million closed in 2017. The remaining agreement is expected to close in early 2018. In March 2015, U.S. Cellular exchanged certain of its unbuilt PCS licenses for certain other PCS licenses located in U.S. Cellular’s existing operating markets and $ 117 million of cash. As of the transaction date, the licenses received in the transaction had an estimated fair value, per a market approach, of $ 43 million. A gain of $ 125 million was recorded in (Gain) loss on license sales and exchanges, net in the Consolidated Statement of Operations in the first quarter of 2015. U.S. Cellular participated in Auction 97 indirectly through its limited partnership interest in Advantage Spectrum. Advantage Spectrum was the provisional winning bidder for 124 licenses for an aggregate winning bid of $ 338 million, after its designated entity discount of 25% . Advantage Spectrum’s bid amount, less the upfront payment of $ 60 million paid in 2014, was paid to the FCC in March 2015. These licenses were granted by the FCC in July 2016. See Note 13 — Variable Interest Entities for additional information. In December 2014, U.S. Cellular entered into an agreement with a third party to sell 595 towers and certain related contracts, assets, and liabilities for $ 159 million. This agreement and related transactions were accomplished in two closings. The first closing occurred in December 2014 and included the sale of 236 towers, without tenants, for $ 10 million. On this same date, U.S. Cellular received $ 8 million in earnest money. At the time of the first closing, a $ 4 million gain was recorded. The second closing for the remaining 359 towers, primarily with tenants, took place in January 2015, at which time U.S. Cellular received $ 142 million in additional cash proceeds and recorded a gain of $ 108 million in (Gain) loss on sale of business and other exit costs, net. In September 2014, U.S. Cellular entered into an agreement with a third party to exchange certain PCS and AWS licenses for certain other PCS and AWS licenses and $ 28 million of cash. This license exchange was accomplished in two closings. The first closing occurred in December 2014 at which time U.S. Cellular transferred licenses to the counterparty with a net book value of $ 11 million, received licenses with an estimated fair value, per a market approach, of $ 52 million, recorded a $ 22 million gain and recorded an $ 18 million deferred credit in Other current liabilities. The license that was transferred to the counterparty in the second closing had a net book value of $ 22 million. The second closing occurred in July 2015. At the time of the second closing, U.S. Cellular received $ 28 million in cash and recognized the deferred credit from the first closing resulting in a total gain of $ 24 million recorded on this part of the license exchange.

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Note 7 Intangible Assets Activity related to U.S. Cellular's Licenses and Goodwill is presented below. See Note 6 — Acquisitions, Divestitures and Exchanges for information regarding transactions which affected Licenses during the periods. Licenses 2017 2016 (Dollars in millions) Balance at beginning of year $ 1,886 $ 1,834 Acquisitions 331 53 Transferred to Assets held for sale (10) (8) Exchanges - Licenses received 25 25 Exchanges - Licenses surrendered (9) (18) Balance at end of year $ 2,223 $ 1,886 Goodwill Year Ended December 31, 2017 2016 (Dollars in millions) Balance at beginning of year $ 370 $ 370 Loss on impairment (370) – Balance at end of year $ – $ 370 Goodwill Interim Impairment Assessment U.S. Cellular operates in an intensely competitive wireless industry environment and has experienced declining service revenues in recent periods. Based on recent 2017 developments, including wireless expansion plans announced by other companies and the results of the FCC’s forward auction of 600 MHz spectrum licenses and other FCC actions, U.S. Cellular anticipates increased competition for customers in its primary operating markets from new and existing market participants over the long term. In addition, the widening adoption of unlimited data plans and other data pricing constructs across the industry, including U.S. Cellular’s introduction of unlimited plans earlier in 2017, may limit the industry’s ability to monetize future growth in data usage. These factors when assessed and considered as part of U.S. Cellular’s annual planning process conducted in the third quarter of each year caused management to revise its long-range financial forecast in the third quarter of 2017. Based on the factors noted above, management identified a triggering event and performed a quantitative goodwill impairment test on an interim basis. U.S. Cellular used a one-step quantitative approach that compared the fair value of the U.S. Cellular reporting unit to its carrying value. A discounted cash flow approach was used to value the reporting unit, using value drivers and risks specific to U.S. Cellular and the industry and current economic factors. The cash flow estimates incorporated certain assumptions that market participants would use in their estimates of fair value and may not be indicative of U.S. Cellular specific assumptions. However, the discount rate used in the analysis considers any additional risk a market participant might place on integrating the U.S. Cellular reporting unit into its operations. The results of the interim goodwill impairment test indicated that the carrying value of the U.S. Cellular reporting unit exceeded its fair value. Therefore, U.S. Cellular recognized a loss on impairment of goodwill of $370 million to reduce the carrying value of goodwill to zero in the third quarter of 2017.

Investments in Unconsolidated E

Investments in Unconsolidated Entities	12 Months Ended
	Dec. 31, 2017
Investments in Unconsolidated Entities [Abstract]
Investments in Unconsolidated Entities	Note 8 Investments in Unconsolidated Entities Investments in unconsolidated entities consist of amounts invested in wireless entities in which U.S. Cellular holds a noncontrolling interest. These investments are accounted for using either the equity or cost method as shown in the following table: December 31, 2017 2016 (Dollars in millions) Equity method investments: Capital contributions, loans, advances and adjustments $ 105 $ 108 Cumulative share of income 1,717 1,577 Cumulative share of distributions (1,411) (1,276) Total equity method investments 411 409 Cost method investments 4 4 Total investments in unconsolidated entities $ 415 $ 413 The following tables, which are based on information provided in part by third parties, summarize the combined assets, liabilities and equity, and results of operations of U.S. Cellular’s equity method investments: December 31, 2017 2016 (Dollars in millions) Assets Current $ 668 $ 739 Due from affiliates 323 387 Property and other 4,804 4,615 Total assets $ 5,795 $ 5,741 Liabilities and Equity Current liabilities $ 435 $ 466 Deferred credits 176 184 Long-term liabilities 199 187 Long-term capital lease obligations 1 6 Partners' capital and shareholders' equity 4,984 4,898 Total liabilities and equity $ 5,795 $ 5,741 Year Ended December 31, 2017 2016 2015 (Dollars in millions) Results of Operations Revenues $ 6,562 $ 6,747 $ 6,958 Operating expenses 4,965 5,047 5,226 Operating income 1,597 1,700 1,732 Other income (expense), net (1) (11) (7) Net income $ 1,596 $ 1,689 $ 1,725

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Note 9 Property, Plant and Equipment Property, plant and equipment in service and under construction, and related accumulated depreciation and amortization, as of December 31, 2017 and 2016 , were as follows: December 31, Useful Lives (Years) 2017 2016 (Dollars in millions) Land N/A $ 36 $ 35 Buildings 20 297 297 Leasehold and land improvements 1-30 1,178 1,153 Cell site equipment 7-25 3,411 3,383 Switching equipment 5-8 988 976 Office furniture and equipment 3-5 389 420 Other operating assets and equipment 3-5 57 53 System development 1-7 1,060 1,217 Work in process N/A 212 178 Total property, plant and equipment, gross 7,628 7,712 Accumulated depreciation and amortization (5,308) (5,242) Total property, plant and equipment, net $ 2,320 $ 2,470 Depreciation and amortization expense totaled $ 604 million, $ 607 million and $ 596 million in 2017 , 2016 and 2015 , respectively. In 2017 , 2016 and 2015 , (Gain) loss on asset disposals, net included charges of $ 17 million, $ 22 million and $ 16 million, respectively, related to disposals of assets, trade-ins of older assets for replacement assets and other retirements of assets from service in the normal course of business.

Asset Retirement Obligation

Asset Retirement Obligation	12 Months Ended
	Dec. 31, 2017
Asset Retirement Obligations [Abstract]
Asset Retirement Obligation	Note 10 Asset Retirement Obligations U.S. Cellular is subject to asset retirement obligations associated with its leased cell sites, switching office sites, retail store sites and office locations in its operating markets. Asset retirement obligations generally include obligations to restore leased land and retail store and office premises to their pre-lease conditions. These obligations are included in Other deferred liabilities and credits in the Consolidated Balance Sheet. In 2017 and 2016 , U.S. Cellular performed a review of the assumptions and estimated costs related to its asset retirement obligations. The results of the reviews (identified as Revisions in estimated cash outflows) and other changes in asset retirement obligations during 2017 and 2016 , were as follows: 2017 2016 (Dollars in millions) Balance at beginning of year $ 174 $ 158 Additional liabilities accrued 1 1 Revisions in estimated cash outflows (3) 5 Disposition of assets (1) (1) Accretion expense 12 11 Balance at end of year $ 183 $ 174

Debt

Debt	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt	Note 11 Debt Revolving Credit Facility At December 31, 2017 , U.S. Cellular had a revolving credit facility available for general corporate purposes, including acquisitions, spectrum purchases and capital expenditures. Amounts under the revolving credit facility may be borrowed, repaid and reborrowed from time to time until maturity in June 2021. As of December 31, 2017 , there were no outstanding borrowings under the revolving credit facility, except for letters of credit. Interest expense representing commitment fees on the unused portion of the revolving line of credit was $ 1 million in each of 2017 , 2016 and 2015 . The commitment fees are based on the unsecured senior debt ratings assigned to U.S. Cellular by certain ratings agencies. The following table summarizes the revolving credit facility as of December 31, 2017 : (Dollars in millions) Maximum borrowing capacity $ 300 Letters of credit outstanding $ 2 Amount borrowed $ – Amount available for use $ 298 Borrowings under the revolving credit facility bear interest either at a LIBOR rate plus 1.75% or at an alternative Base Rate as defined in the revolving credit agreement plus 0.75%, at U.S. Cellular’s option. U.S. Cellular may select a borrowing period of either one, two, three or six months (or other period of twelve months or less if requested by U.S. Cellular and approved by the lenders). U.S. Cellular’s credit spread and commitment fees on its revolving credit facility may be subject to increase if its current credit rating from nationally recognized credit rating agencies is lowered, and may be subject to decrease if the rating is raised. In connection with U.S. Cellular’s revolving credit facility, TDS and U.S. Cellular entered into a subordination agreement dated June 15, 2016, together with the administrative agent for the lenders under U.S. Cellular’s revolving credit agreement. Pursuant to this subordination agreement, (a) any consolidated funded indebtedness from U.S. Cellular to TDS will be unsecured and (b) any (i) consolidated funded indebtedness from U.S. Cellular to TDS (other than “refinancing indebtedness” as defined in the subordination agreement) in excess of $105 million and (ii) refinancing indebtedness in excess of $250 million will be subordinated and made junior in right of payment to the prior payment in full of obligations to the lenders under U.S. Cellular’s revolving credit agreement. As of December 31, 2017 , U.S. Cellular had no outstanding consolidated funded indebtedness or refinancing indebtedness that was subordinated to the revolving credit agreement pursuant to the subordination agreement. The continued availability of the revolving credit facility requires U.S. Cellular to comply with certain negative and affirmative covenants, maintain certain financial ratios and make representations regarding certain matters at the time of each borrowing. U.S. Cellular believes it was in compliance as of December 31, 2017 , with all covenants and other requirements set forth in the revolving credit facility. The revolving credit agreement includes the following financial covenants: Consolidated Interest Coverage Ratio may not be less than 3.00 to 1.00 as of the end of any fiscal quarter. Consolidated Leverage Ratio may not be greater than the ratios indicated as of the end of any fiscal quarter for each period specified below: Period Ratios From the agreement date of June 15, 2016 through June 30, 2019 3.25 to 1.00 From July 1, 2019 and thereafter 3.00 to 1.00 Certain U.S. Cellular wholly-owned subsidiaries have jointly and severally unconditionally guaranteed the payment and performance of the obligations of U.S. Cellular under the revolving credit agreement pursuant to a guaranty dated June 15, 2016. Other subsidiaries that meet certain criteria will be required to provide a similar guaranty in the future. U.S. Cellular believes it was in compliance with all of the financial and other covenants and requirements set forth in its revolving credit facility as of December 31, 2017 . Term Loan In July 2015, U.S. Cellular borrowed $225 million on a senior term loan credit facility in two separate draws. This facility was entered into in January 2015 and amended and restated in June 2016. The interest rate on outstanding borrowings is reset at three and six month intervals at a rate of LIBOR plus 250 basis points. This credit facility provides for the draws to be continued on a long-term basis under terms that are readily determinable. U.S. Cellular has the ability and intent to carry the debt for the duration of the agreement. Principal reductions are due and payable in quarterly installments of $3 million beginning in March 2016 through December 2021, and the remaining unpaid balance will be due and payable in January 2022. The senior term loan credit facility contains financial covenants and subsidiary guarantees that are consistent with the revolving credit agreements described above. This facility was entered into for general corporate purposes, including working capital, spectrum purchases and capital expenditures. U.S. Cellular believes that it was in compliance with all of the financial and other covenants and requirements set forth in its term loan credit facility as of December 31, 2017 . In connection with U.S. Cellular’s term loan credit facility, TDS and U.S. Cellular entered into a subordination agreement in June 2016 together with the administrative agent for the lenders under U.S. Cellular’s term loan credit agreement, which is substantially the same as the subordination agreement for U.S. Cellular as described above under the “Revolving Credit Facilities.” As of December 31, 2017 , U.S. Cellular had no outstanding consolidated funded indebtedness or refinancing indebtedness that was subordinated to the term loan facility pursuant to this subordination agreement. Receivables Securitization Facility In December 2017, U.S. Cellular, through its subsidiaries, entered into a $200 million credit facility to permit securitized borrowings using its equipment installment receivables for general corporate purposes, including acquisitions, spectrum purchases and capital expenditures. In connection with the receivables securitization facility, U.S. Cellular formed a wholly-owned subsidiary, USCC Master Note Trust (Trust), which qualifies as a bankruptcy remote entity. Under the terms of the facility, U.S. Cellular, through its subsidiaries, transfers eligible equipment installment receivables to the Trust. The Trust then utilizes the transferred assets as collateral for notes payables issued to third party financial institutions. Since U.S. Cellular retains effective control of the transferred assets in the Trust, any activity associated with this receivables securitization facility will be treated as a secured borrowing. Therefore, U.S. Cellular will continue to report equipment installment receivables and any related balances on the Consolidated Balance Sheet. Cash received from borrowings under the receivables securitization facility will be reported as Debt. Refer to Note 13 — Variable Interest Entities for additional information. U.S. Cellular entered into a performance guaranty whereby U.S. Cellular guarantees the performance of certain wholly-owned subsidiaries of U.S. Cellular under the receivables securitization facility. Amounts under the receivables securitization facility may be borrowed, repaid and reborrowed from time to time until maturity in December 2019, which may be extended from time to time as specified therein. As of December 31, 2017 , there were no outstanding borrowings under the receivables securitization facility, and the entire unused capacity of $200 million was available, subject to sufficient collateral to satisfy the asset borrowing base provisions of the facility. As of December 31, 2017, the Trust held less than $1 million of assets available to be pledged as collateral for the receivables securitization facility. The continued availability of the receivables securitization facility requires U.S. Cellular to comply with certain negative and affirmative covenants, maintain certain financial ratios and provide representations on certain matters at the time of each borrowing. The covenants include the same financial covenants for U.S. Cellular as described above under the “Revolving Credit Facility.” U.S. Cellular believes that it was in compliance as of December 31, 2017 , with all of the financial covenants and requirements set forth in its receivables securitization facility. Other Long-Term Debt Long-term debt as of December 31, 2017 and 2016 , was as follows: December 31, 2017 December 31, 2016 Issuance date Maturity date Call date (any time on or after) Principal Amount Less Unamortized discount and debt issuance costs Total Principal Amount Less Unamortized discount and debt issuance costs Total (Dollars in millions) Unsecured Senior Notes 6.700% Dec 2003 and June 2004 Dec 2033 Dec 2003 and June 2004 $ 544 $ 15 $ 529 $ 544 $ 15 $ 529 6.950% May 2011 May 2060 May 2016 342 11 331 342 11 331 7.250% Dec 2014 Dec 2063 Dec 2019 275 10 265 275 10 265 7.250% Nov 2015 Dec 2064 Dec 2020 300 10 290 300 10 290 Term Loan Jul 2015 Jan 2022 203 2 201 214 2 212 Capital lease obligations 4 – 4 2 – 2 Installment payment agreement 21 1 20 – – – Total long-term debt $ 1,689 $ 49 $ 1,640 $ 1,677 $ 48 $ 1,629 Long-term debt, current $ 18 $ 11 Long-term debt, noncurrent $ 1,622 $ 1,618 U.S. Cellular may redeem its 6.95% Senior Notes, 7.25% 2063 Senior Notes and 7.25% 2064 Senior Notes, in whole or in part at any time after the respective call date, at a redemption price equal to 100% of the principal amount redeemed plus accrued and unpaid interest. U.S. Cellular may redeem the 6.7% Senior Notes, in whole or in part, at any time prior to maturity at a redemption price equal to the greater of (a) 100% of the principal amount of such notes, plus accrued and unpaid interest, or (b) the sum of the present values of the remaining scheduled payments of principal and interest thereon discounted to the redemption date on a semi-annual basis at the Treasury Rate plus 30 basis points. Interest on the Senior Notes outstanding at December 31, 2017 , is payable quarterly, with the exception of the 6.7% Senior Notes for which interest is payable semi-annually. The annual requirements for principal payments on long-term debt are approximately $ 19 million for each of the years 2018 through 2020 , and $ 11 million and $ 158 million for the years 2021 and 2022 , respectively. The covenants associated with U.S. Cellular’s long-term debt obligations, among other things, restrict U.S. Cellular’s ability, subject to certain exclusions, to incur additional liens, enter into sale and leaseback transactions, and sell, consolidate or merge assets. U.S. Cellular’s long-term debt notes do not contain any provisions resulting in acceleration of the maturities of outstanding debt in the event of a change in U.S. Cellular’s credit rating. However, a downgrade in U.S. Cellular’s credit rating could adversely affect its ability to obtain long-term debt financing in the future.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 12 Commitments and Contingencies Purchase Obligations U.S. Cellular has obligations payable under non-cancellable contracts, commitments for device purchases, network facilities and transport services, agreements for software licensing, long-term marketing programs, as well as certain agreements to purchase goods or services. Where applicable, U.S. Cellular calculates its obligation based on termination fees that can be paid to exit the contract. Future minimum payments required under these commitments are as follows: Purchase Obligations (Dollars in millions) 2018 $ 1,177 2019 657 2020 73 2021 42 2022 21 Thereafter 31 Total $ 2,001 Lease Commitments U.S. Cellular and its subsidiaries have leases for office space, retail store sites, cell sites and equipment which are accounted for as operating leases. Certain leases have renewal options and/or fixed rental increases. Renewal options that are reasonably assured of exercise are included in determining the lease term. Any rent abatements or lease incentives, in addition to fixed rental increases, are included in the calculation of rent expense and calculated on a straight-line basis over the defined lease term. Rent expense totaled $ 166 million, $ 161 million and $ 153 million in 2017 , 2016 and 2015 , respectively. U.S. Cellular and its subsidiaries are also the lessors for tower space which are accounted for as operating leases. The leased assets are included in Property, plant and equipment on the Consolidated Balance Sheet. As of December 31, 2017 , future minimum rental payments required under operating leases and rental receipts expected under operating leases that have noncancellable lease terms in excess of one year were as follows: Operating Leases Future Minimum Rental Payments Operating Leases Future Minimum Rental Receipts (Dollars in millions) 2018 $ 145 $ 54 2019 133 45 2020 120 34 2021 107 21 2022 92 9 Thereafter 737 2 Total $ 1,334 $ 165 Indemnifications U.S. Cellular enters into agreements in the normal course of business that provide for indemnification of counterparties. The terms of the indemnifications vary by agreement. The events or circumstances that would require U.S. Cellular to perform under these indemnities are transaction specific; however, these agreements may require U.S. Cellular to indemnify the counterparty for costs and losses incurred from litigation or claims arising from the underlying transaction. U.S. Cellular is unable to estimate the maximum potential liability for these types of indemnifications as the amounts are dependent on the outcome of future events, the nature and likelihood of which cannot be determined at this time. Historically, U.S. Cellular has not made any significant indemnification payments under such agreements. Legal Proceedings U.S. Cellular is involved or may be involved from time to time in legal proceedings before the FCC, other regulatory authorities, and/or various state and federal courts. If U.S. Cellular believes that a loss arising from such legal proceedings is probable and can be reasonably estimated, an amount is accrued in the financial statements for the estimated loss. If only a range of loss can be determined, the best estimate within that range is accrued; if none of the estimates within that range is better than another, the low end of the range is accrued. The assessment of the expected outcomes of legal proceedings is a highly subjective process that requires judgments about future events. The legal proceedings are reviewed at least quarterly to determine the adequacy of accruals and related financial statement disclosures. The ultimate outcomes of legal proceedings could differ materially from amounts accrued in the financial statements. U.S. Cellular has accrued $ 1 million and less than $ 1 million with respect to legal proceedings and unasserted claims as of December 31, 2017 and 2016 , respectively . U.S. Cellular has not accrued any amount for legal proceedings if it cannot estimate the amount of the possible loss or range of loss. U.S. Cellular is unable to estimate any contingent loss in excess of the amounts accrued.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2017
Variable Interest Entities [Abstract]
Variable Interest Entities	Note 13 Variable Interest Entities Consolidated VIEs U.S. Cellular consolidates variable interest entities (VIEs) in which it has a controlling financial interest as defined by GAAP and is therefore deemed the primary beneficiary. A controlling financial interest will have both of the following characteristics: (a) the power to direct the VIE activities that most significantly impact economic performance and (b) the obligation to absorb the VIE losses and right to receive benefits that are significant to the VIE. U.S. Cellular reviews these criteria initially at the time it enters into agreements and subsequently when events warranting reconsideration occur. These VIEs have risks similar to those described in the “Risk Factors” in U.S. Cellular’s Form 10-K for the year ended December 31, 2017 . During 2017, U.S. Cellular formed USCC EIP LLC (Seller/Sub-Servicer), USCC Receivables Funding LLC (Transferor) and the Trust, special purpose entities (SPEs), to facilitate a securitized borrowing using its equipment installment plan receivables. Under a Receivables Sale Agreement, U.S. Cellular wholly-owned, majority-owned and unconsolidated entities, collectively referred to as “affiliated entities”, transfer device equipment installment contracts to USCC EIP LLC. The Seller/Sub-Servicer will aggregate device equipment installment plan contracts, perform servicing, collection and all other administrative activities related to accounting for equipment installment plan contracts. The Seller/Sub-Servicer will sell the eligible equipment installment plan receivables to the Transferor, a bankruptcy remote entity, which will subsequently sell the receivables to the Trust. The Trust, which is bankruptcy remote and isolated from the creditors of U.S. Cellular, will be responsible for issuing asset-backed variable funding notes (Notes), which are collateralized by the equipment installment plan receivables owned by the Trust. Given that U.S. Cellular has the power to direct the activities of these SPEs, and that these SPEs lack sufficient equity to finance their activities, U.S. Cellular is deemed to have a controlling financial interest in the SPEs and, therefore, consolidates them. All transactions with third parties (e.g. issuance of the asset-backed variable funding notes) will be accounted for as a secured borrowing due to the pledging of equipment installment contracts as collateral, significant continuing involvement in the transferred assets, subordinated interests of the cash flows, and continued evidence of control of the receivables. Refer to Note 11 — Debt, Receivables Securitization Facility for additional details regarding the securitization facility for which these entities were established. The following VIEs were formed to participate in FCC auctions of wireless spectrum and to fund, establish, and provide wireless service with respect to any FCC licenses won in the auctions: Advantage Spectrum, L.P. (Advantage Spectrum) and Sunshine Spectrum, Inc. (Sunshine Spectrum), the general partner of Advantage Spectrum (former general partner was Frequency Advantage, L.P. (Frequency Advantage)); Aquinas Wireless, L.P. (Aquinas Wireless); and King Street Wireless, L.P. (King Street Wireless) and King Street Wireless, Inc., the general partner of King Street Wireless. These particular VIEs are collectively referred to as designated entities. The power to direct the activities that most significantly impact the economic performance of these VIEs is shared. Specifically, the general partner of these VIEs has the exclusive right to manage, operate and control the limited partnerships and make all decisions to carry on the business of the partnerships. The general partner of each partnership needs the consent of the limited partner, an indirect U.S. Cellular subsidiary, to sell or lease certain licenses, to make certain large expenditures, admit other partners or liquidate the limited partnerships. Although the power to direct the activities of these VIEs is shared, U.S. Cellular has the most significant level of exposure to the variability associated with the economic performance of the VIEs, indicating that U.S. Cellular is the primary beneficiary of the VIEs. Therefore, in accordance with GAAP, these VIEs are consolidated. In January 2017, Sunshine Spectrum and the other owner of Frequency Advantage (the previous general partner of Advantage Spectrum) completed a series of transactions whereby Frequency Advantage was dissolved and Sunshine Spectrum became the new general partner of Advantage Spectrum. Consistent with its previous treatment of Frequency Advantage and in accordance with GAAP, U.S. Cellular consolidates Sunshine Spectrum in its financial statements. In March 2015, King Street Wireless made a $ 60 million distribution to its owners. Of this distribution, $ 6 million was provided to King Street Wireless, Inc. and $ 54 million was provided to U.S. Cellular. FCC Auction 97 ended in January 2015. U.S. Cellular participated in Auction 97 indirectly through its interest in Advantage Spectrum. An indirect subsidiary of U.S. Cellular is a limited partner in Advantage Spectrum. Advantage Spectrum applied as a designated entity, and received bid credits with respect to spectrum purchased in Auction 97. Advantage Spectrum was the winning bidder for 124 licenses for an aggregate bid of $ 338 million, after its designated entity discount of 25% . This amount is classified as Licenses in U.S. Cellular’s Consolidated Balance Sheet at December 31, 2017 , and 2016 . Advantage Spectrum’s bid amount, less the initial deposit of $ 60 million paid in 2014, plus certain other charges totaling $ 2 million, was paid to the FCC in March 2015. These licenses were granted by the FCC in July 2016. U.S. Cellular also consolidates other VIEs that are limited partnerships that provide wireless service. A limited partnership is a variable interest entity unless the limited partners hold substantive participating rights or kick-out rights over the general partner. For certain limited partnerships, U.S. Cellular is the general partner and manages the operations. In these partnerships, the limited partners do not have substantive kick-out or participating rights and, further, such limited partners do not have the authority to remove the general partner. Therefore, these limited partnerships are also recognized as VIEs and are consolidated under the variable interest model. The following table presents the classification and balances of the consolidated VIEs’ assets and liabilities in U.S. Cellular’s Consolidated Balance Sheet. December 31, 2017 2016 (Dollars in millions) Assets Cash and cash equivalents $ 3 $ 2 Accounts receivable 476 44 Other current assets 8 6 Assets held for sale – 2 Licenses 655 652 Property, plant and equipment, net 99 105 Other assets and deferred charges 303 16 Total assets $ 1,544 $ 827 Liabilities Current liabilities $ 39 $ 21 Deferred liabilities and credits 13 13 Total liabilities $ 52 $ 34 Unconsolidated VIEs U.S. Cellular manages the operations of and holds a variable interest in certain other limited partnerships, but is not the primary beneficiary of these entities and, therefore, does not consolidate them under the variable interest model. U.S. Cellular’s total investment in these unconsolidated entities was $ 4 million and $ 6 million at December 31, 2017 and 2016 , respectively, and is included in Investments in unconsolidated entities in U.S. Cellular’s Consolidated Balance Sheet. The maximum exposure from unconsolidated VIEs is limited to the investment held by U.S. Cellular in those entities. Other Related Matters U.S. Cellular made contributions, loans and/or advances to its VIEs totaling $ 821 million, of which $ 790 million is related to USCC EIP LLC as discussed above, $ 98 million and $ 281 million during 2017 , 2016 and 2015 , respectively . U.S. Cellular may agree to make additional capital contributions and/or advances to these or other VIEs and/or to their general partners to provide additional funding for operations or the development of licenses granted in various auctions. U.S. Cellular may finance such amounts with a combination of cash on hand, borrowings under its revolving credit agreement and/or other long-term debt. There is no assurance that U.S. Cellular will be able to obtain additional financing on commercially reasonable terms or at all to provide such financial support. The limited partnership agreements of Advantage Spectrum, Aquinas Wireless and King Street Wireless also provide the general partner with a put option whereby the general partner may require the limited partner, a subsidiary of U.S. Cellular, to purchase its interest in the limited partnership. The general partner’s put options related to its interests in King Street Wireless and Aquinas Wireless will become exercisable in 2019 and 2020, respectively. The general partner’s put options related to its interest in Advantage Spectrum will become exercisable in 2021 and 2022. The put option price is determined pursuant to a formula that takes into consideration fixed interest rates and the market value of U.S. Cellular’s Common Shares. Upon exercise of the put option, the general partner is required to repay borrowings due to U.S. Cellular. If the general partner does not elect to exercise its put option, the general partner may trigger an appraisal process in which the limited partner (a subsidiary of U.S. Cellular) may have the right, but not the obligation, to purchase the general partner’s interest in the limited partnership at a price and on other terms and conditions specified in the limited partnership agreement. In accordance with requirements under GAAP, U.S. Cellular is required to calculate a theoretical redemption value for all of the put options assuming they are exercisable at the end of each reporting period, even though such exercise is not contractually permitted. Pursuant to GAAP, this theoretical redemption value, net of amounts payable to U.S. Cellular for loans and accrued interest thereon made by U.S. Cellular to the general partners (net put value), was $ 1 million at December 31, 2017 and 2016 . The net put value is recorded as Noncontrolling interests with redemption features in U.S. Cellular’s Consolidated Balance Sheet. Also in accordance with GAAP, changes in the redemption value of the put options, net of interest accrued on the loans, are recorded as a component of Net income attributable to noncontrolling interests, net of tax, in U.S. Cellular’s Consolidated Statement of Operations. During 2015, U.S. Cellular recorded out-of-period adjustments attributable to the third quarter of 2013 through the second quarter of 2015 related to an agreement with King Street Wireless. U.S. Cellular determined that these adjustments were not material to the quarterly periods or the annual results for 2015. These out-of-period adjustments had the impact of reducing Net income by $ 3 million and Net income attributable to U.S. Cellular shareholders by $ 4 million in 2015.

Noncontrolling Interests

Noncontrolling Interests	12 Months Ended
	Dec. 31, 2017
Noncontrolling Interests [Abstract]
Noncontrolling Interests	Note 14 Noncontrolling Interests U.S. Cellular’s consolidated financial statements include certain noncontrolling interests that meet the GAAP definition of mandatorily redeemable financial instruments. These mandatorily redeemable noncontrolling interests represent interests held by third parties in consolidated partnerships, where the terms of the underlying partnership agreement provide for a defined termination date at which time the assets of the subsidiary are to be sold, the liabilities are to be extinguished and the remaining net proceeds are to be distributed to the noncontrolling interest holders and U.S. Cellular in accordance with the respective partnership agreements. The termination dates of these mandatorily redeemable noncontrolling interests range from 2085 to 2092. The estimated aggregate amount that would be due and payable to settle all of these noncontrolling interests assuming an orderly liquidation of the finite-lived consolidated partnerships on December 31, 2017 , net of estimated liquidation costs, is $ 27 million. This amount excludes redemption amounts recorded in Noncontrolling interests with redemption features in the Consolidated Balance Sheet. The estimate of settlement value was based on certain factors and assumptions which are subjective in nature. Changes in those factors and assumptions could result in a materially larger or smaller settlement amount. U.S. Cellular currently has no plans or intentions relating to the liquidation of any of the related partnerships prior to their scheduled termination dates. The corresponding carrying value of the mandatorily redeemable noncontrolling interests in finite-lived consolidated partnerships at December 31, 2017 , was $ 11 million, and is included in Noncontrolling interests in the Consolidated Balance Sheet. The excess of the aggregate settlement value over the aggregate carrying value of these mandatorily redeemable noncontrolling interests is due primarily to the unrecognized appreciation of the noncontrolling interest holders’ share of the underlying net assets in the consolidated partnerships. Neither the noncontrolling interest holders’ share, nor U.S. Cellular’s share, of the appreciation of the underlying net assets of these subsidiaries is reflected in the consolidated financial statements.

Common Shareholders' Equity

Common Shareholders' Equity	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Common Shareholder's Equity	Note 15 Common Shareholders’ Equity Tax-Deferred Savings Plan At December 31, 2017, U.S. Cellular has reserved 67,215 Common Shares for issuance under the TDS Tax-Deferred Savings Plan, a qualified profit ‑ sharing plan pursuant to Sections 401(a) and 401(k) of the Internal Revenue Code. Participating employees have the option of investing their contributions in a U.S. Cellular Common Share fund, a TDS Common Share fund or certain unaffiliated funds. Series A Common Shares Series A Common Shares are convertible on a share-for-share basis into Common Shares. In matters other than the election of directors, each Series A Common Share is entitled to ten votes per share, compared to one vote for each Common Share. The Series A Common Shares are entitled to elect 75% of the directors (rounded down), and the Common Shares elect 25% of the directors (rounded up). As of December 31, 2017 , a majority of U.S. Cellular’s outstanding Common Shares and all of U.S. Cellular’s outstanding Series A Common Shares were held by TDS. Common Share Repurchase Program In November 2009, the Board of Directors of U.S. Cellular authorized the repurchase of up to 1,300,000 Common Shares on an annual basis beginning in 2009 and continuing each year thereafter, on a cumulative basis. In December 2016, the U.S. Cellular Board amended this authorization to provide that, beginning on January 1, 2017, the authorized repurchase amount with respect to a particular year will be any amount from zero to 1,300,000, as determined by the Pricing Committee, and that if the Pricing Committee did not specify an amount for any year, such amount would be zero for such year. The Pricing Committee did not specify any amount as of January 1, 2018. The Pricing Committee also was authorized to decrease the cumulative amount of the authorization at any time, but has not taken any action to do so at this time. As a result, there was no change to the cumulative amount of the share repurchase authorization as of January 1, 2018. As of December 31, 2017 , the total cumulative amount of Common Shares authorized to be purchased is 5,900,849 . The authorization provides that share repurchases will be made pursuant to open market purchases, block purchases, private purchases, or otherwise, depending on market prices and other conditions. This authorization does not have an expiration date. Pursuant to certain employee and non-employee benefit plans, U.S. Cellular reissued the following Treasury Shares: Year Ended December 31, 2017 2016 2015 (Shares in millions) Treasury Shares Reissued – 1 –

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2017
Share-based Compensation [Abstract]
Stock-Based Compensation	Note 16 Stock-Based Compensation U.S. Cellular has established the following stock ‑ based compensation plans: Long-Term Incentive Plans and a Non-Employee Director compensation plan. Under the U.S. Cellular Long-Term Incentive Plans, U.S. Cellular may grant fixed and performance based incentive and non-qualified stock options, restricted stock, restricted stock units, and deferred compensation stock unit awards to key employees. At December 31, 2017 , the only types of awards outstanding are fixed non-qualified stock option awards, restricted stock unit awards, performance share awards and deferred compensation stock unit awards. Under the Non-Employee Director compensation plan, U.S. Cellular may grant Common Shares to members of the Board of Directors who are not employees of U.S. Cellular or TDS. At December 31, 2017 , U.S. Cellular had reserved 14,449,000 Common Shares for equity awards granted and to be granted under the Long-Term Incentive Plans and 154,000 Common Shares for issuance under the Non-Employee Director compensation plan. U.S. Cellular uses treasury stock to satisfy requirements for Common Shares issued pursuant to its various stock-based compensation plans. Long-Term Incentive Plans – Stock Options Stock options granted to key employees are exercisable over a specified period not in excess of ten years. Stock options generally vest over a period of three years from the date of grant. Stock options outstanding at December 31, 2017 , expire between 2018 and 2026. However, vested stock options typically expire 30 days after the effective date of an employee’s termination of employment for reasons other than retirement. Employees who leave at the age of retirement have 90 days (or one year if they satisfy certain requirements) within which to exercise their vested stock options. The exercise price of options equals the market value of U.S. Cellular Common Shares on the date of grant. U.S. Cellular did not grant stock option awards in 2017. U.S. Cellular estimated the fair value of stock options granted during 2016 and 2015 using the Black-Scholes valuation model and the assumptions shown in the table below. 2016 2015 Expected life 4.7 years 4.6 years Expected annual volatility rate 30.5% 30.1% Dividend yield 0% 0% Risk-free interest rate 1.2% 1.2% Estimated annual forfeiture rate 9.4% 9.7% Pre-vesting forfeitures and expected life are estimated based on historical experience related to similar awards, giving consideration to the contractual terms of the stock-based awards, vesting schedules and expectations of future employee behavior. U.S. Cellular believes that its historical experience provides the best estimates of future pre-vesting forfeitures and future expected life. The expected volatility assumption is based on the historical volatility of U.S. Cellular’s common stock over a period commensurate with the expected life. The dividend yield assumption is zero because U.S. Cellular has never paid a dividend, except a special cash dividend in June 2013, and has expressed its intention to retain all future earnings in the business. The risk-free interest rate assumption is determined using the U.S. Treasury Yield Curve Rate with a term length that approximates the expected life of the stock options. The fair value of options is recognized as compensation cost using an accelerated attribution method over the requisite service periods of the awards, which is generally the vesting period. A summary of U.S. Cellular stock options outstanding (total and portion exercisable) and changes during 2017 is presented in the table below: Common Share Options Number of Options Weighted Average Exercise Price Aggregate Intrinsic Value (in millions) Weighted Average Remaining Contractual Life (in years) Outstanding at December 31, 2016 3,973,000 $ 41.92 (1,937,000 exercisable) $ 42.54 Exercised (162,000) 36.21 Forfeited (74,000) 41.62 Expired (242,000) 57.67 Outstanding at December 31, 2017 3,495,000 $ 41.10 $ 3 6.0 (2,475,000 exercisable) $ 40.79 $ 2 5.4 The weighted average grant date fair value per share of the U.S. Cellular stock options granted in 2016 and 2015 was $ 12.77 and $ 9.94 , respectively. The aggregate intrinsic value of U.S. Cellular stock options exercised in 2017 , 2016 and 2015 was $ 1 million, $ 4 million and $ 2 million, respectively. The aggregate intrinsic value at December 31, 2017 , presented in the table above represents the total pre-tax intrinsic value (the difference between U.S. Cellular’s closing stock price and the exercise price multiplied by the number of in-the-money options) that would have been received by option holders had all options been exercised on December 31, 2017 . Long-Term Incentive Plans – Restricted Stock Units Restricted stock unit awards granted to key employees generally vest after three years. U.S. Cellular estimates the fair value of restricted stock units based on the closing market price of U.S. Cellular shares on the date of grant. The fair value is then recognized as compensation cost on a straight-line basis over the requisite service periods of the awards, which is generally the vesting period. A summary of U.S. Cellular nonvested restricted stock units at December 31, 2017 , and changes during the year then ended is presented in the table below: Common Restricted Stock Units Number Weighted Average Grant Date Fair Value Nonvested at December 31, 2016 1,310,000 $ 40.74 Granted 557,000 38.04 Vested (294,000) 41.24 Forfeited (90,000) 40.07 Nonvested at December 31, 2017 1,483,000 $ 39.67 The total fair value of restricted stock units that vested during 2017 , 2016 and 2015 was $ 11 million, $ 15 million and $ 13 million, respectively. The weighted average grant date fair value per share of the restricted stock units granted in 2017 , 2016 and 2015 was $ 38.04 , $ 43.32 and $ 37.24 , respectively. Long-Term Incentive Plans – Performance Share Awards (Performance Shares) Beginning in 2017, U.S. Cellular granted performance shares, specifically performance stock units, to key employees. The performance shares vest after three years. Each recipient may be entitled to shares of U.S. Cellular common stock equal to 50% to 200% of a communicated target award depending on the achievement of predetermined performance-based operating targets over the performance period, which is a one year period beginning on January 1 in the year of grant to December 31 in the year of grant. The remaining time through the end of the vesting period is considered the “time-based period”. Performance-based operating targets include Simple Free Cash Flow, Consolidated Total Revenue and Postpaid Handset Voluntary Defections. Subject to vesting during the time-based period, the performance share award agreement provides that in no event shall the award be less than 50% of the target opportunity as of the grant date. U.S. Cellular estimates the fair value of performance shares using U.S. Cellular’s closing stock price on the date of grant. An estimate of the number of performance shares expected to vest based upon achieving the performance-based operating targets is made and the aggregate fair value is expensed on a straight-line basis over the requisite service period. Each reporting period, during the performance period, the estimate of the number of performance shares expected to vest is reviewed and stock compensation expense is adjusted as appropriate to reflect the revised estimate of the aggregate fair value of the performance shares expected to vest. A summary of U.S. Cellular’s nonvested performance shares and changes during 2017 is presented in the table below: Common Performance Shares Number Weighted Average Grant Date Fair Value Nonvested at December 31, 2016 – $ – Granted 352,000 $ 36.92 Forfeited (10,000) $ 36.92 Nonvested at December 31, 2017 342,000 $ 36.92 Long-Term Incentive Plans – Deferred Compensation Stock Units Certain U.S. Cellular employees may elect to defer receipt of all or a portion of their annual bonuses and to receive a company matching contribution on the amount deferred. All bonus compensation that is deferred by employees electing to participate is immediately vested and is deemed to be invested in U.S. Cellular Common Share stock units. The amount of U.S. Cellular’s matching contribution depends on the portion of the annual bonus that is deferred. Participants receive a 25% match for amounts deferred up to 50% of their total annual bonus and a 33% match for amounts that exceed 50% of their total annual bonus; such matching contributions also are deemed to be invested in U.S. Cellular Common Share stock units and vest over three years. The total fair value of deferred compensation stock units that vested during 2017 , 2016 and 2015 was less than $ 1 million. The weighted average grant date fair value per share of the deferred compensation stock units granted in 2017 , 2016 and 2015 was $ 36.02 , $ 41.31 and $ 35.96 , respectively. As of December 31, 2017 , there were 21,000 vested but unissued deferred compensation stock units valued at $1 million. Compensation of Non-Employee Directors U.S. Cellular issued 15,000 , 13,000 and 15,000 Common Shares in 2017 , 2016 and 2015 , respectively, under its Non-Employee Director compensation plan. Stock ‑ Based Compensation Expense The following table summarizes stock ‑ based compensation expense recognized during 2017 , 2016 and 2015 : Year Ended December 31, 2017 2016 2015 (Dollars in millions) Stock option awards $ 6 $ 11 $ 11 Restricted stock unit awards 19 14 13 Performance share awards 4 – – Awards under Non-Employee Director compensation plan 1 1 1 Total stock-based compensation expense, before income taxes 30 26 25 Income tax benefit (11) (10) (10) Total stock-based compensation expense, net of income taxes $ 19 $ 16 $ 15 The following table provides a summary of the classification of stock-based compensation expense included in the Consolidated Statement of Operations for the years ended: December 31, 2017 2016 2015 (Dollars in millions) Selling, general and administrative expense $ 27 $ 23 $ 22 System operations expense 3 3 3 Total stock-based compensation expense $ 30 $ 26 $ 25 At December 31, 2017 , unrecognized compensation cost for all U.S. Cellular stock ‑ based compensation awards was $ 32 million and is expected to be recognized over a weighted average period of 1.7 years. U.S. Cellular’s tax benefits realized from the exercise of stock options and other awards totaled $ 5 million in 2017 .

Supplemental Cash Flow Disclosu

Supplemental Cash Flow Disclosures	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Disclosures	Note 17 Supplemental Cash Flow Disclosures Following are supplemental cash flow disclosures regarding interest paid and income taxes paid. Year Ended December 31, 2017 2016 2015 (Dollars in millions) Interest paid $ 111 $ 113 $ 81 Income taxes paid, net of refunds received 55 (11) 59 Following are supplemental cash flow disclosures regarding transactions related to stock-based compensation awards. In certain situations, U.S. Cellular withholds shares that are issuable upon the exercise of stock options or the vesting of restricted shares to cover, and with a value equivalent to, the exercise price and/or the amount of taxes required to be withheld from the stock award holder at the time of the exercise or vesting. U.S. Cellular then pays the amount of the required tax withholdings to the taxing authorities in cash. Year Ended December 31, 2017 2016 2015 (Dollars in millions) Common Shares withheld 144,755 308,010 228,011 Aggregate value of Common Shares withheld $ 6 $ 13 $ 8 Cash receipts upon exercise of stock options 5 12 7 Cash disbursements for payment of taxes (4) (6) (5) Net cash receipts from exercise of stock options and vesting of other stock awards $ 1 $ 6 $ 2

Certain Relationships and Relat

Certain Relationships and Related Transactions	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Certain Relationships and Related Transactions	Note 18 Certain Relationships and Related Transactions The following persons are partners of Sidley Austin LLP, the principal law firm of U.S. Cellular and its subsidiaries: Walter C.D. Carlson, a director of U.S. Cellular, a director and non-executive Chairman of the Board of Directors of TDS and a trustee and beneficiary of a voting trust that controls TDS; William S. DeCarlo, the General Counsel of TDS and an Assistant Secretary of TDS and certain subsidiaries of TDS; and Stephen P. Fitzell, the General Counsel of U.S. Cellular and TDS Telecommunications LLC and an Assistant Secretary of U.S. Cellular and certain other subsidiaries of TDS. Walter C.D. Carlson does not provide legal services to TDS, U.S. Cellular or their subsidiaries. U.S. Cellular and its subsidiaries incurred legal costs from Sidley Austin LLP of $ 7 million, $ 6 million and $ 9 million in 2017 , 2016 and 2015 , respectively . U.S. Cellular is billed for all services it receives from TDS, pursuant to the terms of various agreements between it and TDS. These billings are included in U.S. Cellular's Selling, general and administrative expenses. Some of these agreements were established at a time prior to U.S. Cellular's initial public offering when TDS owned more than 90% of U.S. Cellular's outstanding capital stock and may not reflect terms that would be obtainable from an unrelated third party through arms-length negotiations. Billings from TDS and certain of its subsidiaries to U.S. Cellular are based on expenses specifically identified to U.S. Cellular and on allocations of common expenses. Such allocations are based on the relationship of U.S. Cellular's assets, employees, investment in property, plant and equipment and expenses relative to all subsidiaries in the TDS consolidated group. Management believes the method TDS uses to allocate common expenses is reasonable and that all expenses and costs applicable to U.S. Cellular are reflected in its financial statements. Billings to U.S. Cellular from TDS totaled $ 85 million, $ 94 million and $ 96 million in 2017 , 2016 and 2015 , respectively . In December 2014, U.S. Cellular entered into an agreement to sell 595 towers outside of its core markets to a third party for $ 159 million. The sale of certain of the towers was completed in December 2014, and the sale of the remaining towers was completed in January 2015. See Note 6 – Acquisitions, Divestitures and Exchanges in the Notes to Consolidated Financial Statements. Of the 595 towers, six towers were acquired by U.S. Cellular from Airadigm for a total of $ 3 million. These six towers were included as part of the sale of towers by U.S. Cellular in order to avoid the need for two sets of transaction documents. The value of $ 3 million paid by U.S. Cellular to Airadigm for such six towers was determined using the same method of valuation that was used to value the towers owned by U.S. Cellular that were sold to the third party. The Audit Committee of the board of directors reviewed and evaluated this transaction between U.S. Cellular and Airadigm. The Audit Committee of the Board of Directors of U.S. Cellular is responsible for the review and evaluation of all related-party transactions as such term is defined by the rules of the New York Stock Exchange.

Summary of Significant Accoun26

Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Significant Accounting Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Nature of Operations	U.S. Cellular owns, operates and invests in wireless systems throughout the United States. As of December 31, 2017 , U.S. Cellular served customers with 5.1 million total connections. U.S. Cellular has one reportable segment.
Principles of Consolidation	The accounting policies of U.S. Cellular conform to accounting principles generally accepted in the United States of America (GAAP) as set forth in the Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC). Unless otherwise specified, references to accounting provisions and GAAP in these notes refer to the requirements of the FASB ASC. The consolidated financial statements include the accounts of U.S. Cellular, subsidiaries in which it has a controlling financial interest, general partnerships in which U.S. Cellular has a majority partnership interest and certain entities in which U.S. Cellular has a variable interest that requires consolidation under GAAP. See Note 13 — Variable Interest Entities for additional information relating to U.S. Cellular’s VIEs. All material intercompany accounts and transactions have been eliminated.
Use of Estimates	The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect (a) the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and (b) the reported amounts of revenues and expenses during the reported period. Actual results could differ from those estimates. Significant estimates are involved in accounting for goodwill and indefinite-lived intangible assets, income taxes and equipment installment plans.
Cash, Cash Equivalents, and Restricted Cash	Cash and cash equivalents include cash and highly liquid investments with original maturities of three months or less. Cash and cash equivalents subject to contractual restrictions are classified as restricted cash. On December 31, 2017, U.S. Cellular early adopted the provisions of Accounting Standards Update 2016-18, Statement of Cash Flows: Restricted Cash (ASU 2016-18) on a retrospective basis which requires that restricted cash be presented with cash and cash equivalents in the statement of cash flows. U.S. Cellular had less than $1 million of restricted cash as of December 31, 2017 , and had no restricted cash balances as of December 31, 2016 or 2015 .
Accounts Receivable	Accounts receivable consist primarily of amounts owed by customers for wireless services and equipment sales, including sales of certain devices under equipment installment plans, by agents for sales of equipment to them and by other wireless carriers whose customers have used U.S. Cellular’s wireless systems.
Allowance for Doubtful Accounts	The allowance for doubtful accounts is the best estimate of the amount of probable credit losses related to existing billed and unbilled accounts receivable. The allowance is estimated based on historical experience, account aging and other factors that could affect collectability. Accounts receivable balances are reviewed on either an aggregate or individual basis for collectability depending on the type of receivable. When it is probable that an account balance will not be collected, the account balance is charged against the allowance for doubtful accounts. U.S. Cellular does not have any off-balance sheet credit exposure related to its customers.
Inventory	Inventory consists primarily of wireless devices stated at the lower of cost or net realizable value. Cost is determined using the first-in, first-out method. Net realizable value is determined by reference to the stand-alone selling price.
Intangible Assets	Licenses Licenses consist of direct and incremental costs incurred in acquiring Federal Communications Commission (FCC) licenses to provide wireless service. U.S. Cellular has determined that wireless licenses are indefinite-lived intangible assets and, therefore, not subject to amortization based on the following factors: Radio spectrum is not a depleting asset. The ability to use radio spectrum is not limited to any one technology. U.S. Cellular and its consolidated subsidiaries are licensed to use radio spectrum through the FCC licensing process, which enables licensees to utilize specified portions of the spectrum for the provision of wireless service. U.S. Cellular and its consolidated subsidiaries are required to renew their FCC licenses every ten years or, in some cases, every fifteen years. To date, all of U.S. Cellular’s license renewal applications have been granted by the FCC. Generally, license renewal applications filed by licensees otherwise in compliance with FCC regulations are routinely granted. If, however, a license renewal application is challenged either by a competing applicant for the license or by a petition to deny the renewal application, the license will be renewed if the licensee can demonstrate its entitlement to a “renewal expectancy.” Licensees are entitled to such an expectancy if they can demonstrate to the FCC that they have provided “substantial service” during their license term and have “substantially complied” with FCC rules and policies. U.S. Cellular believes that it is probable that its future license renewal applications will be granted. U.S. Cellular performs its annual impairment assessment of Licenses as of November 1 of each year or more frequently if there are events or circumstances that cause U.S. Cellular to believe the carrying value of Licenses exceeds their fair value on a more likely than not basis. For purposes of its 2017 and 2016 impairment testing of Licenses, U.S. Cellular separated its FCC licenses into eight units of accounting. The eight units of accounting consisted of one unit of accounting for developed operating market licenses (built licenses) and seven geographic non-operating market licenses (unbuilt licenses). U.S. Cellular performed a quantitative impairment assessment in 2017 and a qualitative impairment assessment in 2016 to determine whether it was more likely than not that the fair value of the built and unbuilt licenses exceed their carrying value. Based on the impairment assessments performed, U.S. Cellular did not have an impairment of its Licenses in 2017 or 2016 . See Note 7 — Intangible Assets for additional details related to Licenses. Goodwill U.S. Cellular early adopted Accounting Standards Update 2017-04, Intangibles – Goodwill and Other: Simplifying the Test for Goodwill Impairment (ASU 2017-04), in the third quarter of 2017 and applied the guidance to interim goodwill impairment tests completed in 2017. ASU 2017-04 eliminated Step 2 of the goodwill impairment test. Goodwill impairment loss will be measured as the amount by which a reporting unit’s carrying amount exceeds its fair value. The loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. U.S. Cellular had Goodwill as a result of its acquisitions of wireless businesses. Such Goodwill represents the excess of the total purchase price over the fair value of net assets acquired in these transactions. For purposes of conducting its impairment tests, U.S. Cellular identified one reporting unit. A discounted cash flow approach was used to value the reporting unit for purposes of the Goodwill impairment review. U.S. Cellular performs its annual impairment test as of November 1. However, in the third quarter of 2017, management identified a triggering event and performed an interim impairment test of Goodwill, which resulted in the recognition of an impairment loss of $370 million. U.S. Cellular did not have an impairment of its Goodwill in 2016 . See Note 7 — Intangible Assets for additional details related to Goodwill.
Investments in Unconsolidated Entities	For its equity method investments for which financial information is readily available, U.S. Cellular records its equity in the earnings of the entity in the current period. For its equity method investments for which financial information is not readily available, U.S. Cellular records its equity in the earnings of the entity on a one quarter lag basis.
Property, Plant and Equipment	U.S. Cellular’s Property, plant and equipment is stated at the original cost of construction or purchase including capitalized costs of certain taxes, payroll-related expenses, interest and estimated costs to remove the assets. Expenditures that enhance the productive capacity of assets in service or extend their useful lives are capitalized and depreciated. Expenditures for maintenance and repairs of assets in service are charged to System operations expense or Selling, general and administrative expense, as applicable. Retirements and disposals of assets are recorded by removing the original cost of the asset (along with the related accumulated depreciation) from plant in service and charging it, together with net removal costs (removal costs less an applicable accrued asset retirement obligation and salvage value realized), to (Gain) loss on asset disposals, net. U.S. Cellular capitalizes certain costs of developing new information systems. Software licenses are accounted for as the acquisition of an intangible asset and the incurrence of a liability to the extent that the license fees are not fully paid at acquisition.
Depreciation and amortization	Depreciation is provided using the straight-line method over the estimated useful life of the related asset. U.S. Cellular depreciates leasehold improvement assets associated with leased properties over periods ranging from one to thirty years; such periods approximate the shorter of the assets’ economic lives or the specific lease terms. Useful lives of specific assets are reviewed throughout the year to determine if changes in technology or other business changes would warrant accelerating the depreciation of those specific assets. There were no material changes to useful lives of property, plant and equipment in 2017 , 2016 or 2015 . See Note 9 — Property, Plant and Equipment for additional details related to useful lives.
Impairment of Long-lived Assets	U.S. Cellular reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the assets might be impaired. U.S. Cellular has one asset group for purposes of assessing property, plant and equipment for impairment based on the fact that the individual operating markets are reliant on centrally operated data centers, mobile telephone switching offices and a network operations center. U.S. Cellular operates a single integrated national wireless network. The cash flows generated by this single interdependent network represent the lowest level for which identifiable cash flows are largely independent of the cash flows of other groups of assets and liabilities. In connection with the interim goodwill impairment test in the third quarter of 2017, conditions existed that indicated U.S. Cellular’s long-lived asset group might not be recoverable. As a result, the company performed a long-lived asset recoverability assessment related to the U.S. Cellular asset group and determined that no impairment of the long-lived asset group existed.
Agent Liabilities	U.S. Cellular has relationships with agents, which are independent businesses that obtain customers for U.S. Cellular. At December 31, 2017 and 2016 , U.S. Cellular had accrued $ 61 million and $ 57 million, respectively, for amounts due to agents. These amounts are included in Other current liabilities in the Consolidated Balance Sheet.
Debt Issuance Costs	Debt issuance costs include underwriters’ and legal fees and other charges related to issuing various borrowing instruments and other long-term agreements, and are amortized over the respective term of each instrument. U.S. Cellular presents certain debt issuance costs in the balance sheet as an offset to the related debt obligation. Debt issuance costs related to U.S. Cellular’s revolving credit facility and receivables securitization facility are recorded in Other assets and deferred charges in the Consolidated Balance Sheet.
Asset Retirement Obligations	U.S. Cellular accounts for asset retirement obligations by recording the fair value of a liability for legal obligations associated with an asset retirement in the period in which the obligations are incurred. At the time the liability is incurred, U.S. Cellular records a liability equal to the net present value of the estimated cost of the asset retirement obligation and increases the carrying amount of the related long-lived asset by an equal amount. Until the obligation is fulfilled, U.S. Cellular updates its estimates relating to cash flows required and timing of settlement. U.S. Cellular records the present value of the changes in the future value as an increase or decrease to the liability and the related carrying amount of the long-lived asset. The liability is accreted to future value over a period ending with the estimated settlement date of the respective asset retirement obligation. The carrying amount of the long-lived asset is depreciated over the useful life of the related asset. Upon settlement of the obligation, any difference between the cost to retire the asset and the recorded liability is recognized in the Consolidated Statement of Operations.
Treasury Shares	Common Shares repurchased by U.S. Cellular are recorded at cost as treasury shares and result in a reduction of equity.  When treasury shares are reissued, U.S. Cellular determines the cost using the first-in, first-out cost method.  The difference between the cost of the treasury shares and reissuance price is included in Additional paid-in capital or Retained earnings.
Revenue Recognition	Revenues related to services are recognized as services are rendered. Revenues billed in advance or in arrears of the services being provided are estimated and deferred or accrued, as appropriate. Revenues from sales of equipment and accessories are recognized when U.S. Cellular no longer has any requirements to perform, when title has passed and when the products are accepted by the customer. Multiple Deliverable Arrangements U.S. Cellular sells multiple element service and equipment offerings. In these instances, revenues are allocated using the relative selling price method. Under this method, arrangement consideration is allocated to each element on the basis of its relative selling price. Revenue recognized for the delivered items is limited to the amount due from the customer that is not contingent upon the delivery of additional products or services. Loyalty Reward Program In March 2015, U.S. Cellular announced that it would discontinue its loyalty reward program effective September 1, 2015. All unredeemed reward points expired at that time and the deferred revenue balance of $ 58 million related to such expired points was recognized as service revenues. U.S. Cellular followed the deferred revenue method of accounting for its loyalty reward program. Under this method, revenue allocated to loyalty reward points was deferred. The amount allocated to the loyalty points was based on the estimated retail price of the services and products for which points were redeemable divided by the number of loyalty points required to receive such services and products. This was calculated on a weighted average basis and required U.S. Cellular to estimate the percentage of loyalty points that would be redeemed for each product or service. Revenue was recognized at the time of customer redemption or when such points were depleted via an account maintenance charge. U.S. Cellular employed the proportional model to recognize revenues associated with breakage. Under the proportional model, U.S. Cellular allocated a portion of the estimated future breakage to each redemption and recorded revenue proportionally. Equipment Installment Plans Equipment revenue under equipment installment plan contracts is recognized at the time the device is delivered to the end-user customer for the selling price of the device, net of any deferred imputed interest or trade-in right, if applicable. Imputed interest is reflected as a reduction to the receivable balance and recognized over the duration of the plan as Service revenues. Incentives Discounts and incentives that are deemed cash are recognized as a reduction of Operating revenues concurrently with the associated revenue. U.S. Cellular issues rebates to its agents and end customers. These incentives are recognized as a reduction to revenue at the time the wireless device sale to the customer occurs. The total potential rebates and incentives are reduced by U.S. Cellular’s estimate of rebates that will not be redeemed by customers based on historical experience of such redemptions. From time to time, U.S. Cellular may offer certain promotions to incentivize customers to switch to, or to purchase additional services from, U.S. Cellular. Under these types of promotions, an eligible customer may receive an incentive in the form of a discount off additional services purchased shown as a rebate or credit to the customer’s monthly bill. U.S. Cellular accounts for the future discounts at the time of the initial transaction by allocating and deferring a portion of equipment revenue based on the relative proportion of the future discounts in comparison to the aggregate initial purchase plus the minimum future purchases required to receive the discounts. The deferred revenue will be recognized as service revenue in future periods. Activation Fees U.S. Cellular has charged its end customers activation fees in connection with the sale of certain services and equipment. Device activation fees charged at both agent locations and U.S. Cellular company-owned retail stores in connection with equipment installment plan device transactions are deferred and recognized over a period that corresponds with the equipment upgrade eligibility date based on the contract terms. Device activation fees charged at agent locations in connection with subsidized device sales are deferred and recognized over a period that corresponds with the length of the customer’s service contract. Device activation fees charged at U.S. Cellular company-owned retail stores in connection with subsidized device sales are recognized at the time the device is delivered to the customer. Amounts Collected from Customers and Remitted to Governmental Authorities U.S. Cellular records amounts collected from customers and remitted to governmental authorities on a net basis within a tax liability account if the tax is assessed upon the customer and U.S. Cellular merely acts as an agent in collecting the tax on behalf of the imposing governmental authority. If the tax is assessed upon U.S. Cellular, then amounts collected from customers as recovery of the tax are recorded in Service revenues and amounts remitted to governmental authorities are recorded in Selling, general and administrative expenses in the Consolidated Statement of Operations. The amounts recorded gross in revenues that are billed to customers and remitted to governmental authorities totaled $ 58 million, $ 64 million and $ 77 million for 2017 , 2016 and 2015 , respectively. Eligible Telecommunications Carrier (ETC) Revenues Telecommunications companies may be designated by states, or in some cases by the FCC, as an ETC to receive support payments from the Universal Service Fund if they provide specified services in “high cost” areas. ETC revenues recognized in the reporting period represent the amounts which U.S. Cellular is entitled to receive for such period, as determined and approved in connection with U.S. Cellular’s designation as an ETC in various states.
Advertising Costs	U.S. Cellular expenses advertising costs as incurred. Advertising costs totaled $ 211 million, $ 245 million and $ 231 million in 2017 , 2016 and 2015 , respectively.
Income Taxes	U.S. Cellular is included in a consolidated federal income tax return with other members of the TDS consolidated group. For financial statement purposes, U.S. Cellular and its subsidiaries calculate their income, income taxes and credits as if they comprised a separate affiliated group. Under a tax allocation agreement between TDS and U.S. Cellular, U.S. Cellular remits its applicable income tax payments to TDS. U.S. Cellular had a tax payable balance with TDS of $ 23 million and $ 8 million as of December 31, 2017 and 2016 , respectively . Deferred taxes are computed using the liability method, whereby deferred tax assets are recognized for future deductible temporary differences and operating loss carryforwards, and deferred tax liabilities are recognized for future taxable temporary differences. Both deferred tax assets and liabilities are measured using the tax rates anticipated to be in effect when the temporary differences reverse. Temporary differences are the differences between the reported amounts of assets and liabilities and their tax bases. Deferred tax assets and liabilities are adjusted for the effects of changes in tax laws and rates on the date of enactment. Deferred tax assets are reduced by a valuation allowance when it is more likely than not that some portion or all of the deferred tax assets will not be realized. U.S. Cellular evaluates income tax uncertainties, assesses the probability of the ultimate settlement with the applicable taxing authority and records an amount based on that assessment. Deferred taxes are reported as a net non-current asset or liability by jurisdiction. Any corresponding valuation allowance to reduce the amount of deferred tax assets is also recorded as non-current.
Stock-Based Compensation and Other Plans	U.S. Cellular has established a long-term incentive plan and a non-employee director compensation plan. These plans are considered compensatory plans and, therefore, recognition of compensation cost for grants made under these plans is required. U.S. Cellular recognizes stock compensation expense based upon the fair value of the specific awards granted using established valuation methodologies. The amount of stock compensation cost recognized on either a straight-line basis or graded attribution method is based on the portion of the award that is expected to vest over the requisite service period, which generally represents the vesting period. Stock-based compensation cost recognized has been reduced for estimated forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. See Note 16 — Stock-Based Compensation for additional information.
Defined Contribution Plans	U.S. Cellular participates in a qualified noncontributory defined contribution pension plan sponsored by TDS; such plan provides pension benefits for the employees of U.S. Cellular and its subsidiaries. Under this plan, pension benefits and costs are calculated separately for each participant and are funded currently. Pension costs were $ 11 million in 2017 , 2016 and 2015 . U.S. Cellular also participates in a defined contribution retirement savings plan (401(k) plan) sponsored by TDS. Total costs incurred for U.S. Cellular’s contributions to the 401(k) plan were $ 16 million, $ 16 million and $ 15 million in 2017 , 2016 and 2015 , respectively.
Recently Issued Accounting Pronouncements	In May 2014, the FASB issued Accounting Standards Update 2014-09, Revenue from Contracts with Customers (ASU 2014-09) and has since amended the standard with Accounting Standards Update 2015-14, Revenue from Contracts with Customers: Deferral of the Effective Date , Accounting Standards Update 2016-08, Revenue from Contracts with Customers: Principal versus Agent Considerations (Reporting Revenue Gross versus Net) , Accounting Standards Update 2016-10, Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing , Accounting Standards Update 2016-12, Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients , and Accounting Standards Update 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers . These standards replace existing revenue recognition rules with a single comprehensive model to use in accounting for revenue arising from contracts with customers. U.S. Cellular will adopt ASU 2014-09, as amended, on January 1, 2018, under the modified retrospective transition method whereby a cumulative effect adjustment to retained earnings will be recognized upon adoption and the guidance is applied prospectively. U.S. Cellular has implemented new systems, processes and controls to adopt ASU 2014-09, as amended. ASU 2014-09, as amended, impacts U.S. Cellular’s revenue recognition related to the allocation of contract revenues between various services and equipment, and the timing of when those revenues are recognized. In addition, ASU 2014-09, as amended, requires deferral of incremental contract acquisition and fulfillment costs and subsequent expense recognition over the contract period or expected customer life. Upon adoption, the cumulative effect adjustment will include the establishment of contract asset and contract liability accounts with a corresponding adjustment to retained earnings to reflect the reallocation of revenues between service and equipment performance obligations for which control is transferred to customers in different periods. Reallocation impacts generally arise when bundle discounts are provided in a contract arrangement that includes equipment and service performance obligations. In these cases, the revenue will be reallocated according to the relative stand-alone selling prices of the performance obligations included in the bundle and this may be different than how the revenue is billed to the customer and recognized under current guidance. In addition, contract cost assets will be established to reflect costs that will be deferred as incremental contract acquisition costs. Incremental contract acquisition costs generally relate to commissions paid to sales associates. The cumulative effect of adoption of the new standard will be to increase Retained earnings as of January 1, 2018, by approximately $ 160 million. Based on currently available information, U.S. Cellular estimates that the new standard will not have a significant impact on operating income in 2018. In January 2016, the FASB issued Accounting Standards Update 2016-01, Financial Instruments – Overall: Recognition and Measurement of Financial Assets and Financial Liabilities (ASU 2016-01). This ASU introduces changes to current accounting for equity investments and financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. U.S. Cellular is required to adopt ASU 2016-01 on January 1, 2018, using the modified retrospective approach. The adoption of ASU 2016-01 is not expected to have a significant impact on U.S. Cellular’s financial position or results of operations. In February 2016, the FASB issued Accounting Standards Update 2016-02, Leases (ASU 2016-02). ASU 2016-02 requires lessees to record a right-of-use asset and lease liability for almost all leases. This ASU does not substantially impact the lessor accounting model. However, some changes to the lessor accounting guidance were made to align with lessee accounting changes within Accounting Standards Codification (ASC) 842, Leases and certain key aspects of ASC 606, Revenue from Contracts with Customers. Early adoption is permitted; however, U.S. Cellular plans to adopt ASU 2016-02 on a modified retrospective basis when required on January 1, 2019. In January 2018, the FASB issued Accounting Standards Update 2018-01, Leases (ASU 2018-01), which permits an entity to elect an optional transition practical expedient to not evaluate land easements that exist or expired before the entities adoption of ASU 2016-02. U.S. Cellular plans to adopt ASU 2018-01 in conjunction with its adoption of ASU 2016-02. U.S. Cellular is evaluating the full effect that adoption of ASU 2016-02 and ASU 2018-01 will have on its financial condition, results of operations and disclosures. Upon adoption, U.S. Cellular expects a substantial increase to assets and liabilities on its balance sheet and is in the process of implementing a new lease management and accounting system to assist in the application of the new standard. In March 2016, the FASB issued Accounting Standards Update 2016-04, Liabilities – Extinguishments of Liabilities: Recognition of Breakage from Certain Prepaid Stored-Value Products (ASU 2016-04). ASU 2016-04 requires companies that sell prepaid stored-value products redeemable for goods, services or cash at third-party merchants to recognize breakage (i.e., the value that is ultimately not redeemed by the consumer) in a way that is consistent with how it will be recognized under the new revenue recognition standard. U.S. Cellular is required to adopt ASU 2016-04 on January 1, 2018, retrospectively. The adoption of ASU 2016-04 is not expected to have a significant impact on U.S. Cellular’s financial position or results of operations. In June 2016, the FASB issued Accounting Standards Update 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments (ASU 2016-13). ASU 2016-13 requires entities to use a new forward-looking, expected loss model to estimate credit losses. It also requires additional disclosure relating to the credit quality of trade and other receivables, including information relating to management’s estimate of credit allowances. U.S. Cellular is required to adopt ASU 2016-13 on January 1, 2020, using the modified retrospective approach. Early adoption is permitted as of January 1, 2019. U.S. Cellular is evaluating the effects that adoption of ASU 2016-13 will have on its financial position, results of operations and disclosures. In October 2016, the FASB issued Accounting Standards Update 2016-16, Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory (ASU 2016-16). ASU 2016-16 impacts the accounting for the income tax consequences of intra-entity transfers of assets other than inventory when the transfer occurs between entities in different tax jurisdictions. U.S. Cellular is required to adopt ASU 2016-16 on January 1, 2018, using the modified retrospective approach. The adoption of ASU 2016-16 is not expected to have a significant impact on U.S. Cellular’s financial position or results of operations. In February 2017, the FASB issued Accounting Standards Update 2017-05, Other Income – Gains and Losses from the Derecognition of Nonfinancial Assets: Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets (ASU 2017-05). ASU 2017-05 clarifies how entities account for the derecognition of a nonfinancial asset and adds guidance for partial sales of nonfinancial assets. U.S. Cellular is required to adopt ASU 2017-05 on January 1, 2018, either retrospectively or using the modified retrospective approach. The adoption of ASU 2017-05 is not expected to have a significant impact on U.S. Cellular’s financial position or results of operations. In May 2017, the FASB issued Accounting Standards Update 2017-09, Compensation – Stock Compensation (ASU 2017-09). ASU 2017-09 clarifies when changes to the terms or conditions of share-based payment awards must be accounted for as modifications. U.S. Cellular is required to adopt ASU 2017-09 prospectively on January 1, 2018. The adoption of ASU 2017-09 is not expected to have a significant impact on U.S. Cellular’s financial position or results of operations. In July 2017, the FASB issued Accounting Standards Update 2017-11, Earnings Per Share, Distinguishing Liabilities from Equity, Derivatives and Hedging: I. Accounting for Certain Financial Instruments with Down Round Features, II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (ASU 2017-11). The amendments in Part I of ASU 2017-11 that relate to liability or equity classification of financial instruments (or embedded features) affect all entities that issue financial instruments (for example, warrants or convertible instruments) that include down round features. The amendments in Part II ASU 2017-11 do not have an accounting effect since the amendments only replace the indefinite deferral of certain guidance with a scope exception. U.S. Cellular is required to adopt ASU 2017-11 on January 1, 2019, either retrospectively or using the modified retrospective approach. Early adoption is permitted. The adoption of ASU 2017-11 is not expected to have a significant impact on U.S. Cellular’s financial position or results of operations. In August 2017, the FASB issued Accounting Standards Update 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities (ASU 2017-12). ASU 2017-12 amends hedge accounting recognition and presentation requirements to improve transparency and understandability of information disclosed in the financials as well as simplifies the application of hedge accounting guidance. U.S. Cellular is required to adopt ASU 2017-12 on January 1, 2019, using the modified retrospective approach. Early adoption is permitted. The adoption of ASU 2017-12 is not expected to have a significant impact on U.S. Cellular’s financial position or results of operations.
Legal proceedings	U.S. Cellular is involved or may be involved from time to time in legal proceedings before the FCC, other regulatory authorities, and/or various state and federal courts. If U.S. Cellular believes that a loss arising from such legal proceedings is probable and can be reasonably estimated, an amount is accrued in the financial statements for the estimated loss. If only a range of loss can be determined, the best estimate within that range is accrued; if none of the estimates within that range is better than another, the low end of the range is accrued. The assessment of the expected outcomes of legal proceedings is a highly subjective process that requires judgments about future events. The legal proceedings are reviewed at least quarterly to determine the adequacy of accruals and related financial statement disclosures. The ultimate outcomes of legal proceedings could differ materially from amounts accrued in the financial statements.
Variable Interest Entities	U.S. Cellular consolidates variable interest entities (VIEs) in which it has a controlling financial interest as defined by GAAP and is therefore deemed the primary beneficiary. A controlling financial interest will have both of the following characteristics: (a) the power to direct the VIE activities that most significantly impact economic performance and (b) the obligation to absorb the VIE losses and right to receive benefits that are significant to the VIE. U.S. Cellular reviews these criteria initially at the time it enters into agreements and subsequently when events warranting reconsideration occur. These VIEs have risks similar to those described in the “Risk Factors” in U.S. Cellular’s Form 10-K for the year ended December 31, 2017 .

Fair Value Measurements (Table)

Fair Value Measurements (Table)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair value measurements	U.S. Cellular has applied the provisions of fair value accounting for purposes of computing the fair value of financial instruments for disclosure purposes as displayed below. Level within the Fair Value Hierarchy December 31, 2017 December 31, 2016 Book Value Fair Value Book Value Fair Value (Dollars in millions) Cash and cash equivalents 1 $ 352 $ 352 $ 586 $ 586 Short-term investments 1 50 50 – – Long-term debt Retail 2 917 939 917 929 Institutional 2 534 522 533 532 Other 2 191 191 203 203

Equipment Installment Plans (Ta

Equipment Installment Plans (Table)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Equipment installment plan receivables	The following table summarizes equipment installment plan receivables as of December 31, 2017 and 2016 . December 31, 2017 2016 (Dollars in millions) Equipment installment plan receivables, gross $ 873 $ 628 Deferred interest (80) (53) Equipment installment plan receivables, net of deferred interest 793 575 Allowance for credit losses (65) (50) Equipment installment plan receivables, net $ 728 $ 525 Net balance presented in the Consolidated Balance Sheet as: Accounts receivable — Customers and agents (Current portion) $ 428 $ 345 Other assets and deferred charges (Non-current portion) 300 180 Equipment installment plan receivables, net $ 728 $ 525
Equipment installment plan receivables credit categories	The balance and aging of the equipment installment plan receivables on a gross basis by credit category were as follows: December 31, 2017 December 31, 2016 Lower Risk Higher Risk Total Lower Risk Higher Risk Total (Dollars in millions) Unbilled $ 807 $ 20 $ 827 $ 553 $ 38 $ 591 Billed — current 31 1 32 23 2 25 Billed — past due 12 2 14 10 2 12 Equipment installment plan receivables, gross $ 850 $ 23 $ 873 $ 586 $ 42 $ 628
Equipment installment plans allowance for credit losses	The activity in the allowance for credit losses balance for the equipment installment plan receivables was as follows: 2017 2016 (Dollars in millions) Allowance for credit losses, beginning of year $ 50 $ 26 Bad debts expense 62 63 Write-offs, net of recoveries (47) (39) Allowance for credit losses, end of year $ 65 $ 50

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income taxes receivable (payable)	U.S. Cellular’s current income taxes balances at December 31, 2017 and 2016 , were as follows: December 31, 2017 2016 (Dollars in millions) Federal income taxes payable $ 22 $ 8 Net state income taxes payable 1 –
Income tax expense (benefit)	Income tax expense (benefit) is summarized as follows: Year Ended December 31, 2017 2016 2015 (Dollars in millions) Current Federal $ 68 $ 29 $ 97 State 10 (2) 5 Deferred Federal (354) 1 48 State (11) 5 7 Total income tax expense (benefit) $ (287) $ 33 $ 157
Income tax reconciliation	A reconciliation of U.S. Cellular’s income tax expense computed at the statutory rate to the reported income tax expense, and the statutory federal income tax expense rate to U.S. Cellular’s effective income tax expense rate is as follows: Year Ended December 31, 2017 2016 2015 Amount Rate Amount Rate Amount Rate (Dollars in millions) Statutory federal income tax expense and rate $ (95) 35.0 % $ 29 35.0 % $ 141 35.0 % State income taxes, net of federal benefit 1 (4) 1.4 3 3.6 8 2.1 Effect of noncontrolling interests (2) 0.8 (1) (1.1) 3 0.6 Federal income tax rate change 2 (254) 93.3 – – – – Goodwill impairment 3 71 (26.2) – – – – Other differences, net (3) 1.2 2 2.2 5 1.0 Total income tax expense (benefit) and rate $ (287) 105.5 % $ 33 39.7 % $ 157 38.7 % 1 State income taxes, net of federal benefit, include changes in unrecognized tax benefits as well as adjustments to the valuation allowance. 2 Federal income tax rate change due to the Tax Act reducing the federal income tax rate from 35% to 21% and a corresponding reduction to the deferred tax liability. The amount is slightly different from the total impact of the federal tax rate change because the rate change also impacts the amount of State income taxes, net of federal benefit. 3 Goodwill impairment reflects an adjustment to increase income tax expense by $71 million related to a portion of the impaired goodwill that is not amortizable for income tax purposes. See Note 7 — Intangible Assets for additional information related to the goodwill impairment.
Deferred income tax assets and liabilities	Significant components of U.S. Cellular’s deferred income tax assets and liabilities at December 31, 2017 and 2016 , were as follows: December 31, 2017 2016 (Dollars in millions) Deferred tax assets Net operating loss (NOL) carryforwards $ 103 $ 88 Stock-based compensation 20 26 Compensation and benefits - other 5 21 Deferred rent 21 21 Other 59 56 Total deferred tax assets 208 212 Less valuation allowance (77) (65) Net deferred tax assets 131 147 Deferred tax liabilities Property, plant and equipment 276 473 Licenses/intangibles 192 326 Partnership investments 123 173 Total deferred tax liabilities 591 972 Net deferred income tax liability $ 460 $ 825 Presented in the Consolidated Balance Sheet as: Deferred income tax liability, net $ 461 $ 826 Other assets and deferred charges (1) (1) Net deferred income tax liability $ 460 $ 825
Deferred tax valuation allowance	A summary of U.S. Cellular’s deferred tax asset valuation allowance is as follows: 2017 2016 2015 (Dollars in millions) Balance at beginning of year $ 65 $ 55 $ 53 Charged to income tax expense 12 10 2 Balance at end of year $ 77 $ 65 $ 55
Income tax unrecognized benefits summary	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: 2017 2016 2015 (Dollars in millions) Unrecognized tax benefits balance at beginning of year $ 43 $ 39 $ 36 Additions for tax positions of current year 6 12 7 Additions for tax positions of prior years 1 3 1 Reductions for tax positions of prior years (1) (1) – Reductions for lapses in statutes of limitations (2) (10) (5) Unrecognized tax benefits balance at end of year $ 47 $ 43 $ 39

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings per share	The amounts used in computing earnings per common share and the effects of potentially dilutive securities on the weighted average number of common shares were as follows: Year Ended December 31, 2017 2016 2015 (Dollars and shares in millions, except per share amounts) Net income attributable to U.S. Cellular shareholders $ 12 $ 48 $ 241 Weighted average number of shares used in basic earnings per share 85 85 84 Effect of dilutive securities 1 – 1 Weighted average number of shares used in diluted earnings per share 86 85 85 Basic earnings per share attributable to U.S. Cellular shareholders $ 0.14 $ 0.56 $ 2.86 Diluted earnings per share attributable to U.S. Cellular shareholders $ 0.14 $ 0.56 $ 2.84

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Licenses
Licenses	Licenses 2017 2016 (Dollars in millions) Balance at beginning of year $ 1,886 $ 1,834 Acquisitions 331 53 Transferred to Assets held for sale (10) (8) Exchanges - Licenses received 25 25 Exchanges - Licenses surrendered (9) (18) Balance at end of year $ 2,223 $ 1,886
Goodwill
Goodwill	Goodwill Year Ended December 31, 2017 2016 (Dollars in millions) Balance at beginning of year $ 370 $ 370 Loss on impairment (370) – Balance at end of year $ – $ 370

Investment in Unconsolidated En

Investment in Unconsolidated Entities (Tables)	12 Months Ended
	Dec. 31, 2017
Equity Method Investment, Summarized Financial Information
Equity and cost method investments	Investments in unconsolidated entities consist of amounts invested in wireless entities in which U.S. Cellular holds a noncontrolling interest. These investments are accounted for using either the equity or cost method as shown in the following table: December 31, 2017 2016 (Dollars in millions) Equity method investments: Capital contributions, loans, advances and adjustments $ 105 $ 108 Cumulative share of income 1,717 1,577 Cumulative share of distributions (1,411) (1,276) Total equity method investments 411 409 Cost method investments 4 4 Total investments in unconsolidated entities $ 415 $ 413
Equity method investments, summarized financial position	The following tables, which are based on information provided in part by third parties, summarize the combined assets, liabilities and equity, and results of operations of U.S. Cellular’s equity method investments: December 31, 2017 2016 (Dollars in millions) Assets Current $ 668 $ 739 Due from affiliates 323 387 Property and other 4,804 4,615 Total assets $ 5,795 $ 5,741 Liabilities and Equity Current liabilities $ 435 $ 466 Deferred credits 176 184 Long-term liabilities 199 187 Long-term capital lease obligations 1 6 Partners' capital and shareholders' equity 4,984 4,898 Total liabilities and equity $ 5,795 $ 5,741
Equity method investments, summarized results of operations	Year Ended December 31, 2017 2016 2015 (Dollars in millions) Results of Operations Revenues $ 6,562 $ 6,747 $ 6,958 Operating expenses 4,965 5,047 5,226 Operating income 1,597 1,700 1,732 Other income (expense), net (1) (11) (7) Net income $ 1,596 $ 1,689 $ 1,725

Property, Plant and Equipment (

Property, Plant and Equipment (Table)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, plant and equipment	Property, plant and equipment in service and under construction, and related accumulated depreciation and amortization, as of December 31, 2017 and 2016 , were as follows: December 31, Useful Lives (Years) 2017 2016 (Dollars in millions) Land N/A $ 36 $ 35 Buildings 20 297 297 Leasehold and land improvements 1-30 1,178 1,153 Cell site equipment 7-25 3,411 3,383 Switching equipment 5-8 988 976 Office furniture and equipment 3-5 389 420 Other operating assets and equipment 3-5 57 53 System development 1-7 1,060 1,217 Work in process N/A 212 178 Total property, plant and equipment, gross 7,628 7,712 Accumulated depreciation and amortization (5,308) (5,242) Total property, plant and equipment, net $ 2,320 $ 2,470

Asset Retirement Obligations (T

Asset Retirement Obligations (Table)	12 Months Ended
	Dec. 31, 2017
Asset Retirement Obligations [Abstract]
Asset retirement obligations	In 2017 and 2016 , U.S. Cellular performed a review of the assumptions and estimated costs related to its asset retirement obligations. The results of the reviews (identified as Revisions in estimated cash outflows) and other changes in asset retirement obligations during 2017 and 2016 , were as follows: 2017 2016 (Dollars in millions) Balance at beginning of year $ 174 $ 158 Additional liabilities accrued 1 1 Revisions in estimated cash outflows (3) 5 Disposition of assets (1) (1) Accretion expense 12 11 Balance at end of year $ 183 $ 174

Debt (Table)

Debt (Table)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Revolving credit facilities	The following table summarizes the revolving credit facility as of December 31, 2017 : (Dollars in millions) Maximum borrowing capacity $ 300 Letters of credit outstanding $ 2 Amount borrowed $ – Amount available for use $ 298
Financial covenants	The revolving credit agreement includes the following financial covenants: Consolidated Interest Coverage Ratio may not be less than 3.00 to 1.00 as of the end of any fiscal quarter. Consolidated Leverage Ratio may not be greater than the ratios indicated as of the end of any fiscal quarter for each period specified below: Period Ratios From the agreement date of June 15, 2016 through June 30, 2019 3.25 to 1.00 From July 1, 2019 and thereafter 3.00 to 1.00
Long-term debt	Long-term debt as of December 31, 2017 and 2016 , was as follows: December 31, 2017 December 31, 2016 Issuance date Maturity date Call date (any time on or after) Principal Amount Less Unamortized discount and debt issuance costs Total Principal Amount Less Unamortized discount and debt issuance costs Total (Dollars in millions) Unsecured Senior Notes 6.700% Dec 2003 and June 2004 Dec 2033 Dec 2003 and June 2004 $ 544 $ 15 $ 529 $ 544 $ 15 $ 529 6.950% May 2011 May 2060 May 2016 342 11 331 342 11 331 7.250% Dec 2014 Dec 2063 Dec 2019 275 10 265 275 10 265 7.250% Nov 2015 Dec 2064 Dec 2020 300 10 290 300 10 290 Term Loan Jul 2015 Jan 2022 203 2 201 214 2 212 Capital lease obligations 4 – 4 2 – 2 Installment payment agreement 21 1 20 – – – Total long-term debt $ 1,689 $ 49 $ 1,640 $ 1,677 $ 48 $ 1,629 Long-term debt, current $ 18 $ 11 Long-term debt, noncurrent $ 1,622 $ 1,618

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Purchase Obligations	Future minimum payments required under these commitments are as follows: Purchase Obligations (Dollars in millions) 2018 $ 1,177 2019 657 2020 73 2021 42 2022 21 Thereafter 31 Total $ 2,001
Lease Commitments	As of December 31, 2017 , future minimum rental payments required under operating leases and rental receipts expected under operating leases that have noncancellable lease terms in excess of one year were as follows: Operating Leases Future Minimum Rental Payments Operating Leases Future Minimum Rental Receipts (Dollars in millions) 2018 $ 145 $ 54 2019 133 45 2020 120 34 2021 107 21 2022 92 9 Thereafter 737 2 Total $ 1,334 $ 165

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2017
Variable Interest Entities [Abstract]
Consolidated VIE assets and liabilities	The following table presents the classification and balances of the consolidated VIEs’ assets and liabilities in U.S. Cellular’s Consolidated Balance Sheet. December 31, 2017 2016 (Dollars in millions) Assets Cash and cash equivalents $ 3 $ 2 Accounts receivable 476 44 Other current assets 8 6 Assets held for sale – 2 Licenses 655 652 Property, plant and equipment, net 99 105 Other assets and deferred charges 303 16 Total assets $ 1,544 $ 827 Liabilities Current liabilities $ 39 $ 21 Deferred liabilities and credits 13 13 Total liabilities $ 52 $ 34

Common Shareholders' Equity (Ta

Common Shareholders' Equity (Table)	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Common shareholders' equity	Pursuant to certain employee and non-employee benefit plans, U.S. Cellular reissued the following Treasury Shares: Year Ended December 31, 2017 2016 2015 (Shares in millions) Treasury Shares Reissued – 1 –

Stock-Based Compensation (Table

Stock-Based Compensation (Table)	12 Months Ended
	Dec. 31, 2017
Share-based Compensation [Abstract]
Stock-based compensation, fair value assumptions	U.S. Cellular did not grant stock option awards in 2017. U.S. Cellular estimated the fair value of stock options granted during 2016 and 2015 using the Black-Scholes valuation model and the assumptions shown in the table below. 2016 2015 Expected life 4.7 years 4.6 years Expected annual volatility rate 30.5% 30.1% Dividend yield 0% 0% Risk-free interest rate 1.2% 1.2% Estimated annual forfeiture rate 9.4% 9.7%
Summary of stock options	A summary of U.S. Cellular stock options outstanding (total and portion exercisable) and changes during 2017 is presented in the table below: Common Share Options Number of Options Weighted Average Exercise Price Aggregate Intrinsic Value (in millions) Weighted Average Remaining Contractual Life (in years) Outstanding at December 31, 2016 3,973,000 $ 41.92 (1,937,000 exercisable) $ 42.54 Exercised (162,000) 36.21 Forfeited (74,000) 41.62 Expired (242,000) 57.67 Outstanding at December 31, 2017 3,495,000 $ 41.10 $ 3 6.0 (2,475,000 exercisable) $ 40.79 $ 2 5.4
Summary of nonvested restricted stock units	A summary of U.S. Cellular nonvested restricted stock units at December 31, 2017 , and changes during the year then ended is presented in the table below: Common Restricted Stock Units Number Weighted Average Grant Date Fair Value Nonvested at December 31, 2016 1,310,000 $ 40.74 Granted 557,000 38.04 Vested (294,000) 41.24 Forfeited (90,000) 40.07 Nonvested at December 31, 2017 1,483,000 $ 39.67
Summary of nonvested performance share awards	A summary of U.S. Cellular’s nonvested performance shares and changes during 2017 is presented in the table below: Common Performance Shares Number Weighted Average Grant Date Fair Value Nonvested at December 31, 2016 – $ – Granted 352,000 $ 36.92 Forfeited (10,000) $ 36.92 Nonvested at December 31, 2017 342,000 $ 36.92
Stock-based compensation	The following table summarizes stock ‑ based compensation expense recognized during 2017 , 2016 and 2015 : Year Ended December 31, 2017 2016 2015 (Dollars in millions) Stock option awards $ 6 $ 11 $ 11 Restricted stock unit awards 19 14 13 Performance share awards 4 – – Awards under Non-Employee Director compensation plan 1 1 1 Total stock-based compensation expense, before income taxes 30 26 25 Income tax benefit (11) (10) (10) Total stock-based compensation expense, net of income taxes $ 19 $ 16 $ 15
Stock-based compensation, allocation by financial statement line item	The following table provides a summary of the classification of stock-based compensation expense included in the Consolidated Statement of Operations for the years ended: December 31, 2017 2016 2015 (Dollars in millions) Selling, general and administrative expense $ 27 $ 23 $ 22 System operations expense 3 3 3 Total stock-based compensation expense $ 30 $ 26 $ 25

Supplemental Cash Flow Disclo40

Supplemental Cash Flow Disclosures (Table)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Supplemental cash flow disclosures	Following are supplemental cash flow disclosures regarding interest paid and income taxes paid. Year Ended December 31, 2017 2016 2015 (Dollars in millions) Interest paid $ 111 $ 113 $ 81 Income taxes paid, net of refunds received 55 (11) 59
Stock-based compensation supplemental cash flows	Following are supplemental cash flow disclosures regarding transactions related to stock-based compensation awards. In certain situations, U.S. Cellular withholds shares that are issuable upon the exercise of stock options or the vesting of restricted shares to cover, and with a value equivalent to, the exercise price and/or the amount of taxes required to be withheld from the stock award holder at the time of the exercise or vesting. U.S. Cellular then pays the amount of the required tax withholdings to the taxing authorities in cash. Year Ended December 31, 2017 2016 2015 (Dollars in millions) Common Shares withheld 144,755 308,010 228,011 Aggregate value of Common Shares withheld $ 6 $ 13 $ 8 Cash receipts upon exercise of stock options 5 12 7 Cash disbursements for payment of taxes (4) (6) (5) Net cash receipts from exercise of stock options and vesting of other stock awards $ 1 $ 6 $ 2

Summary of Significant Accoun41

Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Details) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Accounting Policy Disclosures [Line Items]
Number of connections		5,100,000
Number of reportable segments		1
Restricted cash			$ 0	$ 0
Goodwill, Impairment Loss	$ 370	$ 370	0
Agent liability		61	57
Advertising costs		211	245	231
Amounts recorded gross in revenues that are billed to customers and remitted to governmental authorities		58	64	77
Service		2,978	3,081	3,384
Maximum
Accounting Policy Disclosures [Line Items]
Restricted cash		1
Adoption Effect
Accounting Policy Disclosures [Line Items]
Cumulative effect of change in retained earnings due to adoption of new accounting pronouncement		$ 160
TDS
Accounting Policy Disclosures [Line Items]
TDS ownership of U.S. Cellular		83.00%
Income taxes payable		$ 23	8
401(k)
Accounting Policy Disclosures [Line Items]
Defined contribution cost		16	16	15
Pension
Accounting Policy Disclosures [Line Items]
Defined contribution cost		$ 11	$ 11	11
Loyalty Rewards Program
Accounting Policy Disclosures [Line Items]
Service				$ 58

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Financial Instruments
Cash and cash equivalents	$ 352	$ 586
Short-term investments	$ 50	$ 0
Retail | Minimum
Financial Instruments
Fair value assumption, interest rate	4.74%	3.78%
Retail | Maximum
Financial Instruments
Fair value assumption, interest rate	7.13%	6.93%
Fair Value | Level 1
Financial Instruments
Cash and cash equivalents	$ 352	$ 586
Short-term investments	50	0
Fair Value | Level 2 | Retail
Financial Instruments
Long-term debt	939	929
Fair Value | Level 2 | Institutional
Financial Instruments
Long-term debt	522	532
Fair Value | Level 2 | Other
Financial Instruments
Long-term debt	191	203
Book Value
Financial Instruments
Cash and cash equivalents	352	586
Short-term investments	50	0
Book Value | Retail
Financial Instruments
Long-term debt	917	917
Book Value | Institutional
Financial Instruments
Long-term debt	534	533
Book Value | Other
Financial Instruments
Long-term debt	$ 191	$ 203

Equipment Installment Plan Rece

Equipment Installment Plan Receivables, EIP Receivables (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Equipment installment plans [Line Items]
Equipment installment plan receivables, gross	$ 873	$ 628
Deferred interest	(80)	(53)
Equipment installment plan receivables, net of deferred interest	793	575
Allowance for credit losses	(65)	(50)
Equipment installment plan receivables, net	728	525
Accounts receivable - Customers and agents (current portion)
Equipment installment plans [Line Items]
Equipment installment plan receivables, net	428	345
Other assets and deferred charges (Non-current portion)
Equipment installment plans [Line Items]
Equipment installment plan receivables, net	$ 300	$ 180

Equipment Installment Plan Re44

Equipment Installment Plan Receivables, Gross Receivables by Credit Category (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Equipment installment plan receivables, gross	$ 873	$ 628
Unbilled
Financing Receivable, Recorded Investment [Line Items]
Equipment installment plan receivables	827	591
Billed
Financing Receivable, Recorded Investment [Line Items]
Equipment installment plan receivables	32	25
Equipment installment plan receivables, past due	14	12
Lower Risk
Financing Receivable, Recorded Investment [Line Items]
Equipment installment plan receivables, gross	850	586
Lower Risk | Unbilled
Financing Receivable, Recorded Investment [Line Items]
Equipment installment plan receivables	807	553
Lower Risk | Billed
Financing Receivable, Recorded Investment [Line Items]
Equipment installment plan receivables	31	23
Equipment installment plan receivables, past due	12	10
Higher Risk
Financing Receivable, Recorded Investment [Line Items]
Equipment installment plan receivables, gross	23	42
Higher Risk | Unbilled
Financing Receivable, Recorded Investment [Line Items]
Equipment installment plan receivables	20	38
Higher Risk | Billed
Financing Receivable, Recorded Investment [Line Items]
Equipment installment plan receivables	1	2
Equipment installment plan receivables, past due	$ 2	$ 2

Equipment Installment Plan Re45

Equipment Installment Plan Receivables, Allowance for Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Allowance for credit losses
Allowance for credit losses, beginning of year	$ 50
Allowance for credit losses, end of year	65	$ 50
Equipment Installment Plan Receivable
Allowance for credit losses
Allowance for credit losses, beginning of year	50	26
Bad debts expense	62	63
Write-offs, net of recoveries	(47)	(39)
Allowance for credit losses, end of year	$ 65	$ 50

Equipment Installment Plan Re46

Equipment Installment Plan Receivables, Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equipment installment plans [Line Items]
Guarantee liability	$ 15	$ 33
Imputed interest rate	12.50%	11.20%
2016 Equipment installment plans out-of-period adjustment
Equipment installment plans [Line Items]
Out-of-period adjustment description	U.S. Cellular recorded out-of-period adjustments in 2016 due to errors related to equipment installment plan transactions occurring in 2015 (2016 EIP adjustments). The 2016 EIP adjustments had the impact of increasing Equipment sales revenues by $2 million, decreasing bad debts expense, which is a component of Selling, general and administrative expense, by $2 million and increasing Income before income taxes by $4 million in 2016.
2016 Equipment installment plans out-of-period adjustment | Equipment Sales Revenues [Member]
Equipment installment plans [Line Items]
Out-of-period adjustment		$ 2
2016 Equipment installment plans out-of-period adjustment | Selling, general and administrative expense
Equipment installment plans [Line Items]
Out-of-period adjustment		(2)
2016 Equipment installment plans out-of-period adjustment | Income before income taxes
Equipment installment plans [Line Items]
Out-of-period adjustment		$ 4
2015 Equipment installment plans out-of-period adjustment
Equipment installment plans [Line Items]
Out-of-period adjustment description	Additionally, U.S. Cellular recorded out-of-period adjustments in 2015 due to errors related to equipment installment plan transactions (2015 EIP adjustments) that were attributable to 2014. The 2015 EIP adjustments had the impact of reducing Equipment sales revenues and Income before income taxes by $6 million in 2015. U.S. Cellular has determined that these adjustments were not material to any of the periods impacted.
2015 Equipment installment plans out-of-period adjustment | Equipment Sales Revenues [Member]
Equipment installment plans [Line Items]
Out-of-period adjustment			$ (6)
2015 Equipment installment plans out-of-period adjustment | Income before income taxes
Equipment installment plans [Line Items]
Out-of-period adjustment			$ (6)

Income Taxes, Balances (Details

Income Taxes, Balances (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Federal
Income Tax [Line Items]
Income taxes payable	$ 22	$ 8
State
Income Tax [Line Items]
Income taxes payable	$ 1

Income Taxes, Expense (Benefit)

Income Taxes, Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income tax expense (benefit)
Current federal income tax expense	$ 68	$ 29	$ 97
Current state income tax expense (benefit)	10	(2)	5
Deferred federal income tax expense (benefit)	(354)	1	48
Deferred state income tax expense (benefit)	(11)	5	7
Total income tax expense (benefit)	$ (287)	$ 33	$ 157

Income Taxes, Expense Reconcili

Income Taxes, Expense Reconciliation (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income tax expense reconciliation
Statutory federal income tax expense		$ (95)	$ 29	$ 141
State income taxes, net of federal benefit	[1]	(4)	3	8
Effect of noncontrolling interests		(2)	(1)	3
Federal income tax rate change	[2]	(254)	0	0
Goodwill impairment	[3]	71	0	0
Other differences, net		(3)	2	5
Total income tax expense (benefit)		$ (287)	$ 33	$ 157
Income tax rate reconciliation
Statutory federal income tax rate		35.00%	35.00%	35.00%
State income taxes, net of federal benefit	[1]	1.40%	3.60%	2.10%
Effect of noncontrolling interests		0.80%	(1.10%)	0.60%
Federal income tax rate change	[2]	93.30%	0.00%	0.00%
Goodwill impairment	[3]	(26.20%)	0.00%	0.00%
Other differences, net		1.20%	2.20%	1.00%
Total income tax rate		105.50%	39.70%	38.70%
[1]	State income taxes, net of federal benefit, include changes in unrecognized tax benefits as well as adjustments to the valuation allowance.
[2]	Federal income tax rate change due to the Tax Act reducing the federal income tax rate from 35% to 21% and a corresponding reduction to the deferred tax liability. The amount is slightly different from the total impact of the federal tax rate change because the rate change also impacts the amount of State income taxes, net of federal benefit.
[3]	Goodwill impairment reflects an adjustment to increase income tax expense by $71 million related to a portion of the impaired goodwill that is not amortizable for income tax purposes. See Note 7 — Intangible Assets for additional information related to the goodwill impairment.

Income Taxes, Components of Def

Income Taxes, Components of Deferred Income Tax (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets
Net operating loss (NOL) carryforwards	$ 103	$ 88
Stock-based compensation	20	26
Compensation and benefits - other	5	21
Deferred rent	21	21
Other	59	56
Total deferred tax assets	208	212
Less valuation allowance	(77)	(65)
Net deferred tax assets	131	147
Deferred tax liabilities
Property, plant and equipment	276	473
Licenses/intangibles	192	326
Partnership investments	123	173
Total deferred tax liabilities	591	972
Net deferred income tax liability	460	825
Deferred income tax liability, net
Deferred tax liabilities
Net deferred income tax liability	461	826
Other assets and deferred charges (Non-current portion)
Deferred tax liabilities
Net deferred income tax liability	$ (1)	$ (1)

Income Taxes, Net Operating Los

Income Taxes, Net Operating Losses (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
State
Operating Loss Carryforwards [Line Items]
State NOL carryforwards	$ 1,989
Deferred tax asset for State NOL carryforwards	$ 92
State | Minimum
Operating Loss Carryforwards [Line Items]
Expiration of NOL carryforwards	Dec. 31, 2018
State | Maximum
Operating Loss Carryforwards [Line Items]
Expiration of NOL carryforwards	Dec. 31, 2037
Federal
Operating Loss Carryforwards [Line Items]
Deferred tax asset for Federal NOL carryforward	$ 11
Federal | Minimum
Operating Loss Carryforwards [Line Items]
Expiration of NOL carryforwards	Dec. 31, 2018
Federal | Maximum
Operating Loss Carryforwards [Line Items]
Expiration of NOL carryforwards	Dec. 31, 2037

Income Taxes, Deferred Tax Valu

Income Taxes, Deferred Tax Valuation Allowance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred tax valuation allowance, rollfoward
Balance at beginning of year	$ 65
Balance at end of year	77	$ 65
Deferred tax asset valuation allowance
Deferred tax valuation allowance, rollfoward
Balance at beginning of year	65	55	$ 53
Charged to income tax expense	12	10	2
Balance at end of year	$ 77	$ 65	$ 55

Income Taxes, Unrecognized Tax

Income Taxes, Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of unrecognized income tax benefits
Unrecognized tax benefit balance at beginning of year	$ 43	$ 39	$ 36
Additions for tax positions of current year	6	12	7
Additions for tax positions of prior years	1	3	1
Reductions for tax positions of prior years	(1)	(1)
Reductions for lapses in statutes of limitations	(2)	(10)	(5)
Unrecognized tax benefit balance at end of year	$ 47	$ 43	$ 39

Income Taxes, Narrative (Detail

Income Taxes, Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other income tax disclosures
Net accrued interest and penalties	$ 19	$ 15
Interest and penalties expense related to unrecognized income tax benefits	3	(2)	$ 1
Effect of unrecognized tax benefit on income tax expense	$ 38	$ 29	$ 25
Federal income tax rate	35.00%	35.00%	35.00%
Future tax year
Other income tax disclosures
Federal income tax rate	21.00%
State
Other income tax disclosures
All audit periods prior to this year are closed	2,013
Federal
Other income tax disclosures
All audit periods prior to this year are closed	2,013

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings per share
Net income attributable to U.S. Cellular shareholders	$ 12	$ 48	$ 241
Weighted average number of shares used in basic earnings per share	85	85	84
Effects of dilutive securities	1		1
Weighted average number of shares used in diluted earnings per share	86	85	85
Basic earnings per share attributable to U.S. Cellular shareholders	$ 0.14	$ 0.56	$ 2.86
Diluted earnings per share attributable to U.S. Cellular shareholders	$ 0.14	$ 0.56	$ 2.84

Earnings Per Share, Narrative (

Earnings Per Share, Narrative (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings per share, Other disclosures
Antidilutive securities	3	3	4

Acquisitions, Divestitures an57

Acquisitions, Divestitures and Exchanges (Details) $ in Millions

1 Months Ended

3 Months Ended

12 Months Ended

Jul. 31, 2015USD ($)

Mar. 31, 2015USD ($)

Jan. 31, 2015USD ($)

Dec. 31, 2014USD ($)

Sep. 30, 2014USD ($)

Jun. 30, 2017USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Sep. 30, 2016USD ($)

Jun. 30, 2016USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Dec. 31, 2014USD ($)

Apr. 30, 2017USD ($)

Feb. 29, 2016USD ($)

Acquisitions, divestitures and exchanges

Cash received (paid) from divestitures and exchanges

$ 21

$ 21

$ 317

Gain on sale of business and other exit costs

1

114

Gain on license sales and exchanges

22

19

147

Cash paid for licenses

189

53

286

Federal Communications Commission deposit

0

143

$ 0

Other current liabilities

$ 84

90

84

Aggregate license acquisitions

Acquisitions, divestitures and exchanges

Cash paid for licenses

$ 3

53

License acquisition agreement amount

57

$ 57

Auction 1,002

Acquisitions, divestitures and exchanges

Cash paid for licenses

$ 186

Federal Communications Commission deposit

$ 143

Licenses won

188

Total winning bid

$ 329

Auction 97

Acquisitions, divestitures and exchanges

Federal Communications Commission deposit

$ 60

Licenses won

124

Total winning bid

$ 338

Designated entity auction discount

25.00%

License exchange 1

Acquisitions, divestitures and exchanges

Cash received (paid) from divestitures and exchanges

(1)

Gain on license sales and exchanges

3

Carrying value of licenses disposed of in exchange

$ 8

License exchange 2

Acquisitions, divestitures and exchanges

Net cash to be received

$ 28

License exchange 2, first closing

Acquisitions, divestitures and exchanges

Cash received (paid) from divestitures and exchanges

13

Gain on license sales and exchanges

$ 9

License exchange 2, second closing

Acquisitions, divestitures and exchanges

Cash received (paid) from divestitures and exchanges

$ 15

Gain on license sales and exchanges

$ 17

License exchange 3

Acquisitions, divestitures and exchanges

Cash received (paid) from divestitures and exchanges

$ 2

Gain on license sales and exchanges

7

Carrying value of licenses disposed of in exchange

$ 7

License exchange 4

Acquisitions, divestitures and exchanges

Cash received (paid) from divestitures and exchanges

$ 117

Gain on license sales and exchanges

125

Fair value of Licenses received in exchange

$ 43

License exchange 5

Acquisitions, divestitures and exchanges

Cash received (paid) from divestitures and exchanges

$ 28

License exchange 5, first closing

Acquisitions, divestitures and exchanges

Gain on license sales and exchanges

$ 22

Carrying value of licenses disposed of in exchange

11

Fair value of Licenses received in exchange

52

Other current liabilities

18

$ 18

License exchange 5, second closing

Acquisitions, divestitures and exchanges

Cash received (paid) from divestitures and exchanges

$ 28

Gain on license sales and exchanges

24

Carrying value of licenses disposed of in exchange

$ 22

Tower sale

Acquisitions, divestitures and exchanges

Cash received (paid) from divestitures and exchanges

$ 159

Number of towers

595

595

Tower sale, first closing

Acquisitions, divestitures and exchanges

Cash received (paid) from divestitures and exchanges

$ 10

Gain on sale of business and other exit costs

$ 4

Number of towers

236

236

Tower sale, second closing

Acquisitions, divestitures and exchanges

Cash received (paid) from divestitures and exchanges

$ 142

Gain on sale of business and other exit costs

$ 108

Number of towers

359

Earnest money received | Tower sale, first closing

Acquisitions, divestitures and exchanges

Cash received (paid) from divestitures and exchanges

$ 8

Intangible Assets (Details)

Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Goodwill
Balance, beginning of year		$ 370	$ 370
Loss on impairment	$ (370)	(370)	0
Balance, end of year		0	370
Licenses
Licenses
Balance, beginning of period		1,886	1,834
Acquisitions		331	53
Transferred to Assets held for sale		(10)	(8)
Exchanges - Licenses received		25	25
Exchanges - Licenses surrendered		(9)	(18)
Balance, end of period		$ 2,223	$ 1,886

Intangible Assets, Narrative (D

Intangible Assets, Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill
Loss on impairment	$ 370	$ 370	$ 0
Goodwill		$ 0	$ 370	$ 370

Investments in Unconsolidated60

Investments in Unconsolidated Entities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity and cost method investments
Capital contributions, loans, advances and adjustments	$ 105	$ 108
Cumulative share of income	1,717	1,577
Cumulative share of distributions	(1,411)	(1,276)
Total equity method investments	411	409
Cost method investments	4	4
Total investments in unconsolidated entities	415	413
Equity method investments, combined assets
Current	668	739
Due from affiliates	323	387
Property and other	4,804	4,615
Total assets	5,795	5,741
Equity method investments, combined liabilities and equity
Current liabilities	435	466
Deferred credits	176	184
Long-term liabilities	199	187
Long-term capital lease obligations	1	6
Partners' capital and shareholders' equity	4,984	4,898
Total liabilities and equity	5,795	5,741
Equity method investments, combined income statements
Revenues	6,562	6,747	$ 6,958
Operating expenses	4,965	5,047	5,226
Operating income	1,597	1,700	1,732
Other income (expense), net	(1)	(11)	(7)
Net income	$ 1,596	$ 1,689	$ 1,725

Property, Plant and Equipment61

Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment
Land	$ 36	$ 35
Buildings	297	297
Leasehold and land improvements	1,178	1,153
Cell site equipment	3,411	3,383
Switching equipment	988	976
Office furniture and equipment	389	420
Other operating assets and equipment	57	53
System development	1,060	1,217
Work in process	212	178
Property, plant and equipment, gross	7,628	7,712
Accumulated depreciation and amortization	(5,308)	(5,242)
Property, plant and equipment, net	2,320	2,470
Depreciation and amortization expense	604	607	$ 596
(Gain) loss on asset disposals, net	$ 17	$ 22	$ 16
Buildings
Property, Plant and Equipment
Useful life	20 years
Leasehold and land improvements | Minimum
Property, Plant and Equipment
Useful life	1 year
Leasehold and land improvements | Maximum
Property, Plant and Equipment
Useful life	30 years
Cell site equipment | Minimum
Property, Plant and Equipment
Useful life	7 years
Cell site equipment | Maximum
Property, Plant and Equipment
Useful life	25 years
Switching equipment | Minimum
Property, Plant and Equipment
Useful life	5 years
Switching equipment | Maximum
Property, Plant and Equipment
Useful life	8 years
Office furniture and equipment | Minimum
Property, Plant and Equipment
Useful life	3 years
Office furniture and equipment | Maximum
Property, Plant and Equipment
Useful life	5 years
Other operating assets and equipment | Minimum
Property, Plant and Equipment
Useful life	3 years
Other operating assets and equipment | Maximum
Property, Plant and Equipment
Useful life	5 years
System development | Minimum
Property, Plant and Equipment
Useful life	1 year
System development | Maximum
Property, Plant and Equipment
Useful life	7 years

Asset Retirement Obligaion (Det

Asset Retirement Obligaion (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Asset retirement obligation
Asset retirement obligation - Balance at beginning of year	$ 174	$ 158
Additional liabilities accrued	1	1
Revisions in estimated cash outflows	(3)	5
Disposition of assets	(1)	(1)
Accretion expense	12	11
Asset retirement obligation - Balance at end of year	$ 183	$ 174

Debt, revolving credit faciliti

Debt, revolving credit facilities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jul. 01, 2019
Revolving credit
Maximum borrowing capacity	$ 300
Letters of credit outstanding	2
Amount available for use	298
Unused commitment fees	$ 1	$ 1	$ 1
Agreement date	Jun. 15, 2016
Maturity date	Jun. 15, 2021
Interest Coverage Ratio	3
Leverage Ratio	3.25
Future period
Revolving credit
Leverage Ratio				3
U.S. Cellular Revolving credit facility
Revolving credit
Amounts borrowed	$ 0
Subordination agreement description	In connection with U.S. Cellular’s revolving credit facility, TDS and U.S. Cellular entered into a subordination agreement dated June 15, 2016, together with the administrative agent for the lenders under U.S. Cellular’s revolving credit agreement. Pursuant to this subordination agreement, (a) any consolidated funded indebtedness from U.S. Cellular to TDS will be unsecured and (b) any (i) consolidated funded indebtedness from U.S. Cellular to TDS (other than “refinancing indebtedness” as defined in the subordination agreement) in excess of $105 million and (ii) refinancing indebtedness in excess of $250 million will be subordinated and made junior in right of payment to the prior payment in full of obligations to the lenders under U.S. Cellular’s revolving credit agreement. As of December 31, 2017, U.S. Cellular had no outstanding consolidated funded indebtedness or refinancing indebtedness that was subordinated to the revolving credit agreement pursuant to the subordination agreement.
U.S. Cellular Revolving credit facility | LIBOR rate
Revolving credit
Contractual spread	1.75%
U.S. Cellular Revolving credit facility | Alternative Base Rate
Revolving credit
Contractual spread	0.75%
Receivables securitization facility
Revolving credit
Maximum borrowing capacity	$ 200
Amounts borrowed	$ 0
Revolver compliance	U.S. Cellular believes that it was in compliance as of December 31, 2017, with all of the financial covenants and requirements set forth in its receivables securitization facility.
Receivables securitization facility | Maximum
Revolving credit
Amount available for use	$ 1

Debt, term loan facility (Detai

Debt, term loan facility (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jul. 31, 2015
Long-term debt
Principal Amount	$ 1,689	$ 1,677
U.S. Cellular Term loan facility
Long-term debt
Principal Amount	203	$ 214	$ 225
Term Loan periodic payment amount	$ 3
Frequency of periodic Term Loan payment	quarterly
Date of debt issuance	Jul. 20, 2015
Maturity date of debt issued	Jan. 21, 2022
Payment terms	In July 2015, U.S. Cellular borrowed $225 million on a senior term loan credit facility in two separate draws. This facility was entered into in January 2015 and amended and restated in June 2016. The interest rate on outstanding borrowings is reset at three and six month intervals at a rate of LIBOR plus 250 basis points. This credit facility provides for the draws to be continued on a long-term basis under terms that are readily determinable. U.S. Cellular has the ability and intent to carry the debt for the duration of the agreement. Principal reductions are due and payable in quarterly installments of $3 million beginning in March 2016 through December 2021, and the remaining unpaid balance will be due and payable in January 2022. The senior term loan credit facility contains financial covenants and subsidiary guarantees that are consistent with the revolving credit agreements described above. This facility was entered into for general corporate purposes, including working capital, spectrum purchases and capital expenditures.
Subordination agreement description	In connection with U.S. Cellular’s term loan credit facility, TDS and U.S. Cellular entered into a subordination agreement in June 2016 together with the administrative agent for the lenders under U.S. Cellular’s term loan credit agreement, which is substantially the same as the subordination agreement for U.S. Cellular as described above under the “Revolving Credit Facilities.” As of December 31, 2017, U.S. Cellular had no outstanding consolidated funded indebtedness or refinancing indebtedness that was subordinated to the term loan facility pursuant to this subordination agreement.
Term loan compliance	U.S. Cellular believes that it was in compliance with all of the financial and other covenants and requirements set forth in its term loan credit facility as of December 31, 2017.
U.S. Cellular Term loan facility | LIBOR rate
Long-term debt
Contractual spread	2.50%

Debt, long-term debt (Details)

Debt, long-term debt (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jul. 31, 2015
Long-term debt
Principal Amount	$ 1,689	$ 1,677
Unamortized discount and debt issuance costs	49	48
Total long-term debt	1,640	1,629
Current portion of long-term debt	18	11
Long-term debt, net	1,622	1,618
Long-term debt maturities
Scheduled principal payments 2018	19
Scheduled principal payments 2019	19
Scheduled principal payments 2020	19
Scheduled principal payments 2021	11
Scheduled principal payments 2022	$ 158
6.7% Senior Notes
Long-term debt
Interest rate on debt	6.70%
Maturity date of debt issued	Dec. 15, 2033
Principal Amount	$ 544	544
Unamortized discount and debt issuance costs	15	15
Long term debt	$ 529	529
6.7% Senior Notes | Minimum
Long-term debt
Date of debt issuance	Dec. 8, 2003
Call date of debt issued	Dec. 8, 2003
6.7% Senior Notes | Maximum
Long-term debt
Date of debt issuance	Jun. 28, 2004
Call date of debt issued	Jun. 28, 2004
6.95% Senior Notes
Long-term debt
Interest rate on debt	6.95%
Date of debt issuance	May 9, 2011
Maturity date of debt issued	May 15, 2060
Call date of debt issued	May 15, 2016
Principal Amount	$ 342	342
Unamortized discount and debt issuance costs	11	11
Long term debt	$ 331	331
7.25% Senior Notes due 2063
Long-term debt
Interest rate on debt	7.25%
Date of debt issuance	Dec. 8, 2014
Maturity date of debt issued	Dec. 1, 2063
Call date of debt issued	Dec. 8, 2019
Principal Amount	$ 275	275
Unamortized discount and debt issuance costs	10	10
Long term debt	$ 265	265
7.25% Senior Notes due 2064
Long-term debt
Interest rate on debt	7.25%
Date of debt issuance	Nov. 23, 2015
Maturity date of debt issued	Dec. 1, 2064
Call date of debt issued	Dec. 1, 2020
Principal Amount	$ 300	300
Unamortized discount and debt issuance costs	10	10
Long term debt	$ 290	290
U.S. Cellular Term loan facility
Long-term debt
Date of debt issuance	Jul. 20, 2015
Maturity date of debt issued	Jan. 21, 2022
Principal Amount	$ 203	214	$ 225
Unamortized discount and debt issuance costs	2	2
Long term debt	201	212
Capital lease obligations
Long-term debt
Principal Amount	4	2
Unamortized discount and debt issuance costs	0	0
Capital lease obligations	4	2
Installment payment agreement
Long-term debt
Principal Amount	21	0
Unamortized discount and debt issuance costs	1	0
Long term debt	$ 20	$ 0

Commitments And Contingencies P

Commitments And Contingencies Purchase Obligations (Details) $ in Millions	Dec. 31, 2017USD ($)
Purchase Obligations
2,018	$ 1,177
2,019	657
2,020	73
2,021	42
2,022	21
Thereafter	31
Total	$ 2,001

Commitments and Contingencies,

Commitments and Contingencies, Minimum lease obligations (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
Operating leases description	U.S. Cellular and its subsidiaries have leases for office space, retail store sites, cell sites and equipment which are accounted for as operating leases. Certain leases have renewal options and/or fixed rental increases. Renewal options that are reasonably assured of exercise are included in determining the lease term. Any rent abatements or lease incentives, in addition to fixed rental increases, are included in the calculation of rent expense and calculated on a straight-line basis over the defined lease term. Rent expense totaled $166 million, $161 million and $153 million in 2017, 2016 and 2015, respectively.
Operating Leases Future Minimum Payments Due
2,018	$ 145
2,019	133
2,020	120
2,021	107
2,022	92
Thereafter	737
Total	1,334
Operating Leases Future Minimum Receipts
2,018	54
2,019	45
2,020	34
2,021	21
2,022	9
Thereafter	2
Total	$ 165

Commitments and Contingencies68

Commitments and Contingencies, Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Leases, Rent Expense
Rent expense	$ 166	$ 161	$ 153
Loss Contingency, Estimate
Accrual for legal proceedings and unasserted claims	$ 1
Maximum
Loss Contingency, Estimate
Accrual for legal proceedings and unasserted claims		$ 1

Variable Interest Entities (Det

Variable Interest Entities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 352	$ 586
Accounts receivable	775	658
Other current assets	21	23
Assets held for sale	10	8
Licenses	2,223	1,886
Property, plant and equipment, net	2,320	2,470
Other assets and deferred charges	390	405
Liabilities
Current liabilities	733	718
Consolidated Variable Interest Entities
Assets
Cash and cash equivalents	3	2
Accounts receivable	476	44
Other current assets	8	6
Assets held for sale	0	2
Licenses	655	652
Property, plant and equipment, net	99	105
Other assets and deferred charges	303	16
Total assets	1,544	827
Liabilities
Current liabilities	39	21
Deferred liabilities and credits	13	13
Total liabilities	$ 52	$ 34

Variable Interest Entities, Nar

Variable Interest Entities, Narrative (Details) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2015USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Variable Interest Entities, Other Disclosures
Federal Communications Commission deposit		$ 0	$ 143	$ 0
Capital contributions, loans or advances		821	98	281
Investments in unconsolidated entities		415	413
Noncontrolling interests with redemption features		$ 1	1
King Street Wireless out-of-period adjustment
Variable Interest Entities, Other Disclosures
Out-of-period adjustment description		During 2015, U.S. Cellular recorded out-of-period adjustments attributable to the third quarter of 2013 through the second quarter of 2015 related to an agreement with King Street Wireless. U.S. Cellular determined that these adjustments were not material to the quarterly periods or the annual results for 2015. These out-of-period adjustments had the impact of reducing Net income by $3 million and Net income attributable to U.S. Cellular shareholders by $4 million in 2015.
Net income | King Street Wireless out-of-period adjustment
Variable Interest Entities, Other Disclosures
Out-of-period adjustment				(3)
Net income attributable to U.S. Cellular shareholders | King Street Wireless out-of-period adjustment
Variable Interest Entities, Other Disclosures
Out-of-period adjustment				$ (4)
USCC EIP LLC
Variable Interest Entities, Other Disclosures
Capital contributions, loans or advances		$ 790
Unconsolidated Variable Interest Entities
Variable Interest Entities, Other Disclosures
Investments in unconsolidated entities		$ 4	$ 6
King Street Wireless L.P.
Variable Interest Entities, Other Disclosures
Cash distributions paid	$ 60
King Street Wireless, L.P. distribution paid to U.S. Cellular	54
King Street Wireless, L.P. distribution paid to King Street Wireless, Inc.	$ 6
Advantage Spectrum L.P.
Variable Interest Entities, Other Disclosures
Licenses won	124
Total winning bid	$ 338
Designated entity auction discount	25.00%
Other auction charges	$ 2

Noncontrolling Interests (Detai

Noncontrolling Interests (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Redeemable noncontrolling interest
Termination date range of mandatorily redeemable noncontrolling interests - begin	2,085
Termination date range of mandatorily redeemable noncontrolling interests - end	2,092
Settlement value of mandatorily redeemable noncontrolling interests	$ 27
Carrying value of mandatorily redeemable noncontrolling interests	$ 11

Common Shareholders' Equity (De

Common Shareholders' Equity (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share repurchases
Common share repurchase authorization	In November 2009, the Board of Directors of U.S. Cellular authorized the repurchase of up to 1,300,000 Common Shares on an annual basis beginning in 2009 and continuing each year thereafter, on a cumulative basis.  In December 2016, the U.S. Cellular Board amended this authorization to provide that, beginning on January 1, 2017, the authorized repurchase amount with respect to a particular year will be any amount from zero to 1,300,000, as determined by the Pricing Committee, and that if the Pricing Committee did not specify an amount for any year, such amount would be zero for such year.  The Pricing Committee did not specify any amount as of January 1, 2018.  The Pricing Committee also was authorized to decrease the cumulative amount of the authorization at any time, but has not taken any action to do so at this time.  As a result, there was no change to the cumulative amount of the share repurchase authorization as of January 1, 2018.  As of December 31, 2017, the total cumulative amount of Common Shares authorized to be purchased is 5,900,849. The authorization provides that share repurchases will be made pursuant to open market purchases, block purchases, private purchases, or otherwise, depending on market prices and other conditions.  This authorization does not have an expiration date.
Series A Common Shares
Common shareholders' equity, other disclosures
Voting rights for number of board of directors	75%
Common Shares
Common shareholders' equity, other disclosures
Voting rights for number of board of directors	25%
Common Shares | 401(k)
Common shareholders' equity, other disclosures
Shares reserved	67,215
Common Shares | Treasury shares
Common shareholders' equity, other disclosures
Shares reissued		1,000,000
Share repurchases
Repurchase expiration	This authorization does not have an expiration date.
Repurchase authorization, cumulative shares authorized	5,900,849
Common Shares | Treasury shares | Minimum
Share repurchases
Repurchase authorization, additional number of shares per year	0
Common Shares | Treasury shares | Maximum
Share repurchases
Repurchase authorization, additional number of shares per year	1,300,000

Stock-Based Compensation Overvi

Stock-Based Compensation Overview (Details)	12 Months Ended
	Dec. 31, 2017shares
Long-Term Incentive Plans
Stock-based compensation, overview
Description of awards	Under the U.S. Cellular Long-Term Incentive Plans, U.S. Cellular may grant fixed and performance based incentive and non-qualified stock options, restricted stock, restricted stock units, and deferred compensation stock unit awards to key employees. At December 31, 2017, the only types of awards outstanding are fixed non-qualified stock option awards, restricted stock unit awards, performance share awards and deferred compensation stock unit awards.
Common Shares | Long-Term Incentive Plans
Stock-based compensation, overview
Shares reserved	14,449,000
Common Shares | Non-Employee Directors' Plan
Stock-based compensation, overview
Shares reserved	154,000

Stock-Based Compensation Stock

Stock-Based Compensation Stock Options and Valuation Model (Details) - Long-Term Incentive Plans - Stock Options - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-based compensation, stock options, overview
Terms of award	Stock options granted to key employees are exercisable over a specified period not in excess of ten years. Stock options generally vest over a period of three years from the date of grant. Stock options outstanding at December 31, 2017, expire between 2018 and 2026. However, vested stock options typically expire 30 days after the effective date of an employee’s termination of employment for reasons other than retirement. Employees who leave at the age of retirement have 90 days (or one year if they satisfy certain requirements) within which to exercise their vested stock options. The exercise price of options equals the market value of U.S. Cellular Common Shares on the date of grant.
Minimum
Stock-based compensation, stock options, overview
Stock options expiration date	Apr. 1, 2018
Maximum
Stock-based compensation, stock options, overview
Stock options expiration date	Apr. 1, 2026
Common Shares
Black Scholes valuation model assumptions
Expected life		4 years 8 months	4 years 7 months
Expected annual volatility rate		30.50%	30.10%
Dividend yield		0.00%	0.00%
Risk-free interest rate		1.20%	1.20%
Estimated annual forfeiture rate		9.40%	9.70%
Stock compensation, stock option rollforward schedule, number of options
Outstanding, begin of period	3,973,000
Exercisable options, begin of period	1,937,000
Granted options	0
Exercised options	(162,000)
Forfeited options	(74,000)
Expired options	(242,000)
Outstanding, end of period	3,495,000	3,973,000
Exercisable options, end of period	2,475,000	1,937,000
Stock compensation, stock option rollforward schedule, other information
Options outstanding, begin of period - weighted average exercise price	$ 41.92
Options exercisable, begin of period - weighted average exercise price	42.54
Options exercised, weighted average exercise price	36.21
Options forfeited, weighted average exercise price	41.62
Options expired, weighted average exercise price	57.67
Options outstanding, end of period - weighted average exercise price	41.10	$ 41.92
Options exercisable, end of period - weighted average exercise price	$ 40.79	42.54
Options granted, weighted average grant date fair value		$ 12.77	$ 9.94
Aggregate intrinsic value, options exercised	$ 1	$ 4	$ 2
Aggregate intrinsic value, options outstanding	3
Aggregate intrinsic value, options exercisable	$ 2
Weighted average remaining contractual life, outstanding	6 years
Weighted average remaining contractual life, exercisable	5 years 5 months

Stock-Based Compensation Restri

Stock-Based Compensation Restricted Stock Units (Details) - Long-Term Incentive Plans - Restricted Stock Units - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Terms of award	Restricted stock unit awards granted to key employees generally vest after three years. U.S. Cellular estimates the fair value of restricted stock units based on the closing market price of U.S. Cellular shares on the date of grant. The fair value is then recognized as compensation cost on a straight-line basis over the requisite service periods of the awards, which is generally the vesting period.
Common Shares
Stock based compensation, Nonvested shares rollforward, number of shares
Nonvested stock units, begin of period - Number of shares	1,310,000
Granted number of shares	557,000
Vested number of shares	(294,000)
Forfeited number of shares	(90,000)
Nonvested stock units, end of period - Number of shares	1,483,000	1,310,000
Stock based compensation, Nonvested shares weighted average grant date fair value
Nonvested stock units - begin of period weighted average grant date fair value	$ 40.74
Granted weighted average grant date fair value	38.04	$ 43.32	$ 37.24
Vested weighted average grant date fair value	41.24
Forfeited weighted average grant date fair value	40.07
Nonvested stock units - end of period weighted average grant date fair value	$ 39.67	$ 40.74
Fair value of vested stock units	$ 11	$ 15	$ 13

Stock-Based Compensation Perfor

Stock-Based Compensation Performance Stock Units (Details) - Long-Term Incentive Plans - Performance Shares	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Terms of award	Beginning in 2017, U.S. Cellular granted performance shares, specifically performance stock units, to key employees. The performance shares vest after three years. Each recipient may be entitled to shares of U.S. Cellular common stock equal to 50% to 200% of a communicated target award depending on the achievement of predetermined performance-based operating targets over the performance period, which is a one year period beginning on January 1 in the year of grant to December 31 in the year of grant. The remaining time through the end of the vesting period is considered the “time-based period”. Performance-based operating targets include Simple Free Cash Flow, Consolidated Total Revenue and Postpaid Handset Voluntary Defections. Subject to vesting during the time-based period, the performance share award agreement provides that in no event shall the award be less than 50% of the target opportunity as of the grant date.
Common Shares
Stock based compensation, Nonvested shares rollforward, number of shares
Nonvested stock units, begin of period - Number of shares | shares	0
Granted number of shares | shares	352,000
Forfeited number of shares | shares	(10,000)
Nonvested stock units, end of period - Number of shares | shares	342,000
Stock based compensation, Nonvested shares weighted average grant date fair value
Nonvested stock units - begin of period weighted average grant date fair value | $ / shares	$ 0
Granted weighted average grant date fair value | $ / shares	36.92
Forfeited weighted average grant date fair value | $ / shares	36.92
Nonvested stock units - end of period weighted average grant date fair value | $ / shares	$ 36.92
Common Shares | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards target	50.00%
Common Shares | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards target	200.00%

Stock-Based Compensation Other

Stock-Based Compensation Other Plans (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Long-Term Incentive Plans | Deferred Compensation Stock Units
Long-Term Incentive Plan, deferred compensation description
Deferred compensation arrangement description	Certain U.S. Cellular employees may elect to defer receipt of all or a portion of their annual bonuses and to receive a company matching contribution on the amount deferred. All bonus compensation that is deferred by employees electing to participate is immediately vested and is deemed to be invested in U.S. Cellular Common Share stock units. The amount of U.S. Cellular’s matching contribution depends on the portion of the annual bonus that is deferred. Participants receive a 25% match for amounts deferred up to 50% of their total annual bonus and a 33% match for amounts that exceed 50% of their total annual bonus; such matching contributions also are deemed to be invested in U.S. Cellular Common Share stock units and vest over three years.
Common Shares | Non-Employee Directors' Plan
Shares issued and granted under stock compensation plans
Shares issued	15,000	13,000	15,000
Common Shares | Long-Term Incentive Plans | Deferred Compensation Stock Units
Shares issued and granted under stock compensation plans
Vested number of shares, unissued	21,000
Vested number of shares, unissued, fair value	$ 1
Stock based compensation, Nonvested shares weighted average grant date fair value
Granted weighted average grant date fair value	$ 36.02	$ 41.31	$ 35.96
Common Shares | Long-Term Incentive Plans | Deferred Compensation Stock Units | Maximum
Stock based compensation, Nonvested shares weighted average grant date fair value
Fair value of vested stock units	$ 1	$ 1	$ 1

Stock-Based Compensation Expens

Stock-Based Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock based compensation expense
Total stock-based compensation expense, before income taxes	$ 30	$ 26	$ 25
Income tax benefit	(11)	(10)	(10)
Total stock-based compensation expense, net of income taxes	19	16	15
Unrecognized compensation cost for all stock-based compensation awards	$ 32
Weighted average period for recognition of unrecognized compensation cost for all stock-based compensation awards	1 year 8 months
Tax benefit from exercise of stock options and other awards	$ 5
System operations expense
Stock based compensation expense
Total stock-based compensation expense, before income taxes	3	3	3
Selling, general and administrative expense
Stock based compensation expense
Total stock-based compensation expense, before income taxes	27	23	22
Long-Term Incentive Plans | Stock Options
Stock based compensation expense
Total stock-based compensation expense, before income taxes	6	11	11
Long-Term Incentive Plans | Restricted Stock Units
Stock based compensation expense
Total stock-based compensation expense, before income taxes	19	14	13
Long-Term Incentive Plans | Performance Shares
Stock based compensation expense
Total stock-based compensation expense, before income taxes	4	0	0
Non-Employee Directors' Plan
Stock based compensation expense
Total stock-based compensation expense, before income taxes	$ 1	$ 1	$ 1

Supplemental Cash Flow Disclo79

Supplemental Cash Flow Disclosures (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental cash flow disclosures
Interest paid	$ 111	$ 113	$ 81
Income taxes paid, net of refunds received	55	(11)	59
Supplemental cash flows, stock based compensation
Cash receipts upon exercise of stock options	5	12	7
Cash disbursements for payments of taxes	(4)	(6)	(5)
Net cash receipts from exercise of stock options and vesting of other stock awards	$ 1	$ 6	$ 2
Common Shares
Supplemental cash flows, stock based compensation
Shares withheld	144,755	308,010	228,011
Aggregate value of shares withheld	$ 6	$ 13	$ 8

Certain Relationships and Rel80

Certain Relationships and Related Transactions (Details) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2014USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Related Party Transaction [Line Items]
Billings to U.S. Cellular from TDS		$ 85	$ 94	$ 96
Cash received from divestitures and exchanges		21	21	317
Tower sale
Related Party Transaction [Line Items]
Number of towers	595
Cash received from divestitures and exchanges	$ 159
Sidley Austin LLP
Related Party Transaction [Line Items]
Legal expense		$ 7	6	9
Description of related transaction		The following persons are partners of Sidley Austin LLP, the principal law firm of U.S. Cellular and its subsidiaries: Walter C.D. Carlson, a director of U.S. Cellular, a director and non-executive Chairman of the Board of Directors of TDS and a trustee and beneficiary of a voting trust that controls TDS; William S. DeCarlo, the General Counsel of TDS and an Assistant Secretary of TDS and certain subsidiaries of TDS; and Stephen P. Fitzell, the General Counsel of U.S. Cellular and TDS Telecommunications LLC and an Assistant Secretary of U.S. Cellular and certain other subsidiaries of TDS. Walter C.D. Carlson does not provide legal services to TDS, U.S. Cellular or their subsidiaries. U.S. Cellular and its subsidiaries incurred legal costs from Sidley Austin LLP of $7 million, $6 million and $9 million in 2017, 2016 and 2015, respectively.
Airadigm Communications, Inc. | Tower sale
Related Party Transaction [Line Items]
Description of related transaction		In December 2014, U.S. Cellular entered into an agreement to sell 595 towers outside of its core markets to a third party for $159 million. The sale of certain of the towers was completed in December 2014, and the sale of the remaining towers was completed in January 2015. See Note 6 – Acquisitions, Divestitures and Exchanges in the Notes to Consolidated Financial Statements. Of the 595 towers, six towers were acquired by U.S. Cellular from Airadigm for a total of $3 million. These six towers were included as part of the sale of towers by U.S. Cellular in order to avoid the need for two sets of transaction documents. The value of $3 million paid by U.S. Cellular to Airadigm for such six towers was determined using the same method of valuation that was used to value the towers owned by U.S. Cellular that were sold to the third party. The Audit Committee of the board of directors reviewed and evaluated this transaction between U.S. Cellular and Airadigm.
Number of towers purchased	6
Purchase price	$ 3
TDS
Related Party Transaction [Line Items]
Description of related transaction		U.S. Cellular is billed for all services it receives from TDS, pursuant to the terms of various agreements between it and TDS. These billings are included in U.S. Cellular's Selling, general and administrative expenses. Some of these agreements were established at a time prior to U.S. Cellular's initial public offering when TDS owned more than 90% of U.S. Cellular's outstanding capital stock and may not reflect terms that would be obtainable from an unrelated third party through arms-length negotiations. Billings from TDS and certain of its subsidiaries to U.S. Cellular are based on expenses specifically identified to U.S. Cellular and on allocations of common expenses. Such allocations are based on the relationship of U.S. Cellular's assets, employees, investment in property, plant and equipment and expenses relative to all subsidiaries in the TDS consolidated group. Management believes the method TDS uses to allocate common expenses is reasonable and that all expenses and costs applicable to U.S. Cellular are reflected in its financial statements. Billings to U.S. Cellular from TDS totaled $85 million, $94 million and $96 million in 2017, 2016 and 2015, respectively
Billings to U.S. Cellular from TDS		$ 85	$ 94	$ 96
TDS ownership percentage		83.00%