Lumen (LUMN) 10-K 11 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2018	Feb. 22, 2019	Jun. 30, 2018
Document and Entity Information
Entity Registrant Name	CENTURYLINK, INC
Entity Central Index Key	0000018926
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 17.7
Entity Common Stock, Shares Outstanding (shares)		1,079,783,226
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
OPERATING REVENUE	$ 23,443	$ 17,656	$ 17,470
OPERATING EXPENSES
Cost of services and products (exclusive of depreciation and amortization)	10,862	8,203	7,774
Selling, general and administrative	4,165	3,508	3,447
Depreciation and amortization	5,120	3,936	3,916
Goodwill impairment	2,726	0	0
Total operating expenses	22,873	15,647	15,137
OPERATING INCOME	570	2,009	2,333
OTHER (EXPENSE) INCOME
Interest expense	(2,177)	(1,481)	(1,318)
Other income, net	44	12	5
Total other expense, net	(2,133)	(1,469)	(1,313)
INCOME (LOSS) BEFORE INCOME TAX EXPENSE	(1,563)	540	1,020
Income tax expense (benefit)	170	(849)	394
NET (LOSS) INCOME	$ (1,733)	$ 1,389	$ 626
BASIC AND DILUTED (LOSS) EARNINGS PER COMMON SHARE
BASIC (in dollars per share)	$ (1.63)	$ 2.21	$ 1.16
DILUTED (in dollars per share)	$ (1.63)	$ 2.21	$ 1.16
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING
BASIC (in shares)	1,065,866	627,808	539,549
DILUTED (in shares)	1,065,866	628,693	540,679

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (1,733)	$ 1,389	$ 626
Items related to employee benefit plans:
Change in net actuarial gain (loss), net of ($45), $(60) and $113 tax	133	83	(168)
Change in net prior service credit, net of $(3), $(4) and $(4) tax	9	8	6
Foreign currency translation adjustment and other, net of $50, $(17) and $— tax	(201)	31	(21)
Net current-period other comprehensive income (loss)	(59)	122	(183)
COMPREHENSIVE (LOSS) INCOME	$ (1,792)	$ 1,511	$ 443

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Change in net actuarial gain (loss), tax	$ (45)	$ (60)	$ 113
Change in net prior service credit, tax	(3)	(4)	(4)
Foreign currency translation adjustment and other, tax	$ 50	$ (17)	$ 0

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
CURRENT ASSETS
Cash and cash equivalents	$ 488	$ 551
Restricted cash - current	4	5
Accounts receivable, less allowance of $142 and $164	2,398	2,557
Assets held for sale	12	140
Other	918	941
Total current assets	3,820	4,194
NET PROPERTY, PLANT AND EQUIPMENT
Property, plant and equipment	53,267	51,204
Accumulated depreciation	(26,859)	(24,352)
Net property, plant and equipment	26,408	26,852
GOODWILL AND OTHER ASSETS
Goodwill	28,031	30,475
Restricted cash	26	31
Customer relationships, net	8,911	10,876
Other intangible assets, net	1,868	1,897
Other, net	1,192	1,286
Total goodwill and other assets	40,028	44,565
TOTAL ASSETS	70,256	75,611
CURRENT LIABILITIES
Current maturities of long-term debt	652	443
Accounts payable	1,933	1,555
Accrued expenses and other liabilities
Salaries and benefits	1,104	890
Income and other taxes	337	370
Interest	316	363
Other	357	344
Advance billings and customer deposits	832	892
Total current liabilities	5,531	4,857
LONG-TERM DEBT	35,409	37,283
DEFERRED CREDITS AND OTHER LIABILITIES
Deferred income taxes, net	2,527	2,413
Benefit plan obligations, net	4,319	5,178
Other	2,642	2,389
Total deferred credits and other liabilities	9,488	9,980
COMMITMENTS AND CONTINGENCIES (Note 17)
STOCKHOLDERS' EQUITY
Preferred stock — non-redeemable, $25.00 par value, authorized 2,000 and 2,000 shares, issued and outstanding 7 and 7 shares	0	0
Common stock, $1.00 par value, authorized 1,600,000 and 1,600,000 shares, issued and outstanding 1,080,167 and 1,069,169 shares	1,080	1,069
Additional paid-in capital	22,852	23,314
Accumulated other comprehensive loss	(2,461)	(1,995)
(Accumulated deficit) retained earnings	(1,643)	1,103
Total stockholders' equity	19,828	23,491
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 70,256	$ 75,611

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accounts receivable, allowance	$ 142	$ 164
Preferred stock-non-redeemable, par value (in dollars per share)	$ 25	$ 25
Preferred stock-non-redeemable, authorized shares (shares)	2,000,000	2,000,000
Preferred stock-non-redeemable, issued shares (shares)	7,000	7,000
Preferred stock-non-redeemable, outstanding shares (shares)	7,000	7,000
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, authorized shares (shares)	1,600,000,000	1,600,000,000
Common stock, issued shares (shares)	1,080,167,000	1,069,169,000
Common stock, outstanding shares (shares)	1,080,167,000	1,069,169,000

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES
Net (loss) income	$ (1,733)	$ 1,389	$ 626
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	5,120	3,936	3,916
Impairment of goodwill and other assets	2,746	0	13
Deferred income taxes	522	(931)	6
Loss on the sale of data centers and colocation business	0	82	0
Provision for uncollectible accounts	153	176	192
Net long-term debt issuance costs and premium amortization	13	9	2
Net loss on early retirement of debt	7	5	27
Share-based compensation	186	111	80
Changes in current assets and liabilities:
Accounts receivable	25	31	(266)
Accounts payable	124	(123)	109
Accrued income and other taxes	75	54	(43)
Other current assets and liabilities, net	127	(614)	92
Retirement benefits	(667)	(202)	(152)
Changes in other noncurrent assets and liabilities, net	329	(174)	(18)
Other, net	5	129	24
Net cash provided by operating activities	7,032	3,878	4,608
INVESTING ACTIVITIES
Payments for property, plant and equipment and capitalized software	(3,175)	(3,106)	(2,981)
Cash paid for Level 3 acquisition, net of $2.3 billion cash acquired	0	(7,289)	0
Proceeds from sale of property and intangible assets	158	1,529	30
Other, net	(61)	(5)	(43)
Net cash used in investing activities	(3,078)	(8,871)	(2,994)
FINANCING ACTIVITIES
Net proceeds from issuance of long-term debt	130	8,398	2,161
Proceeds from financing obligation (Note 3)	0	356	0
Payments of long-term debt	(1,936)	(1,963)	(2,462)
Net proceeds (payments) on credit facility and revolving line of credit	145	35	(40)
Dividends paid	(2,312)	(1,453)	(1,167)
Other, net	(50)	(17)	(10)
Net cash (used in) provided by financing activities	(4,023)	5,356	(1,518)
Net (decrease) increase in cash, cash equivalents and restricted cash	(69)	363	96
Cash, cash equivalents and restricted cash at beginning of period	587	224	128
Cash, cash equivalents and restricted cash at end of period	518	587	224
Supplemental cash flow information:
Income taxes received (paid), net	674	(392)	(397)
Interest paid (net of capitalized interest of $53, $78 and $54)	(2,138)	(1,401)	(1,301)
Cash, cash equivalents and restricted cash:
Total	$ 587	$ 224	$ 128

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Cash Flows [Abstract]
Interest paid (net of capitalized interest of $53, $78 and $54)	$ 53	$ 78	$ 54
Cash acquired for Level 3 acquisition		$ 2,300

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	ACCUMULATED OTHER COMPREHENSIVE LOSS	RETAINED EARNINGS (ACCUMULATED DEFICIT)
Balance at beginning of period at Dec. 31, 2015		$ 544	$ 15,178	$ (1,934)	$ 272
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	$ 626				626
Issuance of common stock to acquire Level 3, including replacement of Level 3's share-based compensation awards		0	0
Issuance of common stock through dividend reinvestment, incentive and benefit plans		3	7
Shares withheld to satisfy tax withholdings			(15)
Share-based compensation and other, net			79
Acquisition of additional minority interest in a subsidiary			0
Other comprehensive (loss) income	(183)			(183)
Dividends declared			(279)		(899)
Balance at end of period at Dec. 31, 2016	$ 13,399	547	14,970	(2,117)	(1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
DIVIDENDS DECLARED PER COMMON SHARE (usd per share)	$ 2.16
Cumulative effect of adoption | Accounting Standards Update 2018-02				0	0
Cumulative effect of adoption | Accounting Standards Update 2014-09					0
Cumulative effect of adoption | Accounting Standards Update 2016-09					0
Net (loss) income	$ 1,389				1,389
Issuance of common stock to acquire Level 3, including replacement of Level 3's share-based compensation awards		517	9,462
Issuance of common stock through dividend reinvestment, incentive and benefit plans		5	0
Shares withheld to satisfy tax withholdings			(20)
Share-based compensation and other, net			79
Acquisition of additional minority interest in a subsidiary			0
Other comprehensive (loss) income	122			122
Dividends declared			(1,177)		(288)
Balance at end of period at Dec. 31, 2017	$ 23,491	1,069	23,314	(1,995)	1,103
Increase (Decrease) in Stockholders' Equity [Roll Forward]
DIVIDENDS DECLARED PER COMMON SHARE (usd per share)	$ 2.16
Cumulative effect of adoption | Accounting Standards Update 2018-02				0	0
Cumulative effect of adoption | Accounting Standards Update 2014-09					0
Cumulative effect of adoption | Accounting Standards Update 2016-09					3
Net (loss) income	$ (1,733)				(1,733)
Issuance of common stock to acquire Level 3, including replacement of Level 3's share-based compensation awards		0	(2)
Issuance of common stock through dividend reinvestment, incentive and benefit plans		11	0
Shares withheld to satisfy tax withholdings			(56)
Share-based compensation and other, net			187
Acquisition of additional minority interest in a subsidiary			(5)
Other comprehensive (loss) income	(59)			(59)
Dividends declared			(586)		(1,758)
Balance at end of period at Dec. 31, 2018	$ 19,828	$ 1,080	$ 22,852	(2,461)	(1,643)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
DIVIDENDS DECLARED PER COMMON SHARE (usd per share)	$ 2.16
Cumulative effect of adoption | Accounting Standards Update 2018-02				$ (407)	407
Cumulative effect of adoption | Accounting Standards Update 2014-09					338
Cumulative effect of adoption | Accounting Standards Update 2016-09					$ 0

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (PARENTHETICAL) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
RETAINED EARNINGS (ACCUMULATED DEFICIT) | Accounting Standards Update 2014-09
Cumulative net effect of adoption of ASU, tax	$ (119)	$ 0	$ 0

Background and Summary of Signi

Background and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Background and Summary of Significant Accounting Policies	Background and Summary of Significant Accounting Policies General We are an international facilities-based communications company engaged primarily in providing a broad array of integrated services to our residential and business customers. On November 1, 2017, we acquired Level 3 Communications, Inc. ("Level 3") in a cash and stock transaction. See Note 2—Acquisition of Level 3 for additional information. On May 1, 2017, we sold our data centers and colocation business to a consortium of private equity purchasers for a combination of cash and equity. See Note 3—Sale of Data Centers and Colocation Business for additional information. Basis of Presentation The accompanying consolidated financial statements include our accounts and the accounts of our subsidiaries in which we have a controlling interest. These subsidiaries include Level 3 on and after November 1, 2017. Intercompany amounts and transactions with our consolidated subsidiaries have been eliminated. In connection with our acquisition of Level 3, we acquired its deconsolidated Venezuela subsidiary and due to exchange restrictions and other conditions we have assigned no value to this subsidiary's assets. Additionally, we have excluded this subsidiary from our consolidated financial statements. To simplify the overall presentation of our consolidated financial statements, we report immaterial amounts attributable to noncontrolling interests in certain of our subsidiaries as follows: (i) income attributable to noncontrolling interests in other income, net, (ii) equity attributable to noncontrolling interests in additional paid-in capital and (iii) cash flows attributable to noncontrolling interests in other, net financing activities. We reclassified certain prior period amounts to conform to the current period presentation, including the categorization of our revenue and our segment reporting for 2018 , 2017 and 2016 . See Note 15—Segment Information for additional information. These changes had no impact on total operating revenue, total operating expenses or net (loss) income for any period. Summary of Significant Accounting Policies Use of Estimates Our consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles. These accounting principles require us to make certain estimates, judgments and assumptions. We believe that the estimates, judgments and assumptions we make when accounting for specific items and matters, including, but not limited to, revenue recognition, revenue reserves, network access costs, network access cost dispute reserves, investments, long-term contracts, customer retention patterns, allowance for doubtful accounts, depreciation, amortization, asset valuations, internal labor capitalization rates, recoverability of assets (including deferred tax assets), impairment assessments, pension, post-retirement and other post-employment benefits, taxes, certain liabilities and other provisions and contingencies, are reasonable, based on information available at the time they are made. These estimates, judgments and assumptions can materially affect the reported amounts of assets, liabilities and components of stockholders' equity as of the dates of the consolidated balance sheets, as well as the reported amounts of revenue, expenses and components of cash flows during the periods presented in our other consolidated financial statements. We also make estimates in our assessments of potential losses in relation to threatened or pending tax and legal matters. See Note 14—Income Taxes and Note 17—Commitments, Contingencies and Other Items for additional information. For matters not related to income taxes, if a loss is considered probable and the amount can be reasonably estimated, we recognize an expense for the estimated loss. If we have the potential to recover a portion of the estimated loss from a third party, we make a separate assessment of recoverability and reduce the estimated loss if recovery is also deemed probable. For matters related to income taxes, if we determine that the impact of an uncertain tax position is more likely than not to be sustained upon audit by the relevant taxing authority, then we recognize a benefit for the largest amount that is more likely than not to be sustained. No portion of an uncertain tax position will be recognized if the position has less than a 50% likelihood of being sustained. Interest is recognized on the amount of unrecognized benefit from uncertain tax positions. For all of these and other matters, actual results could differ materially from our estimates. Revenue Recognition We earn most of our consolidated revenue from contracts with customers, primarily through the provision of telecommunications and other services. Revenue from contracts with customers is accounted for under Accounting Standards Codification ("ASC") 606. We also earn revenue from leasing arrangements (primarily fiber capacity agreements) and governmental subsidy payments, neither of which are accounted for under ASC 606. Revenue is recognized when control of the promised goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to receive in exchange for those goods or services. Revenue is recognized based on the following five-step model: • Identification of the contract with a customer; • Identification of the performance obligations in the contract; • Determination of the transaction price; • Allocation of the transaction price to the performance obligations in the contract; and • Recognition of revenue when, or as, we satisfy a performance obligation. We provide an array of communications services to residential and business customers, including local voice, VPN, Ethernet, data, broadband, private line (including special access), network access, transport, voice, information technology, video and other ancillary services. We provide these services to a wide range of businesses, including global/international, enterprise, wholesale, government, small and medium business customers. Certain contracts also include the sale of equipment, which is not significant to our business. We recognize revenue for services when we provide the applicable service or when control is transferred. Recognition of certain payments received in advance of services being provided is deferred. These advance payments include certain activation and certain installation charges. If the activation and installation charges are not separate performance obligations, we recognize them as revenue over the actual or expected contract term using historical experience, which ranges from one year to seven years depending on the service. In most cases, termination fees or other fees on existing contracts that are negotiated in conjunction with new contracts are deferred and recognized over the new contract term. For access services, we generally bill fixed monthly charges one month in advance to customers and recognize revenue as service is provided over the contract term in alignment with the customer's receipt of service. For usage and other ancillary services, we generally bill in arrears and recognize revenue as usage or delivery occurs. In certain cases, customers may be permitted to modify their contracts. We evaluate the change in scope or price to identify whether the modification should be treated as a separate contract, whether the modification is a termination of the existing contract and creation of a new contract, or if it is a change to the existing contract. Customer contracts are evaluated to determine whether the performance obligations are separable. If the performance obligations are deemed separable and separate earnings processes exist, the total transaction price that we expect to receive with the customer is allocated to each performance obligation based on its relative standalone selling price. The revenue associated with each performance obligation is then recognized as earned. We periodically sell optical capacity on our network. These transactions are structured as indefeasible rights of use, commonly referred to as IRUs, which are the exclusive right to use a specified amount of capacity or fiber for a specified term, typically 10 to 20 years. In most cases, we account for the cash consideration received on transfers of optical capacity as ASC 606 revenue which we recognize ratably over the term of the agreement. Cash consideration received on transfers of dark fiber is adjusted for the time value of money and is accounted for as non-ASC 606 lease revenue, which we also recognize ratably over the term of the agreement. We do not recognize revenue on any contemporaneous exchanges of our optical capacity assets for other non-owned optical capacity assets. In connection with offering products and services provided to the end user by third-party vendors, we review the relationship between us, the vendor and the end user to assess whether revenue should be reported on a gross or net basis. In assessing whether revenue should be reported on a gross or net basis, we consider whether we act as a principal in the transaction and control the goods and services used to fulfill the performance obligations associated with the transaction. We have service level commitments pursuant to contracts with certain of our customers. To the extent that such service levels are not achieved or are otherwise disputed due to performance or service issues or other service interruptions or conditions, we will estimate the amount of credits to be issued and record a corresponding reduction to revenue in the period that the service level commitment was not met. Customer payments are made based on billing schedules included in our customer contracts, which is typically on a monthly basis. We defer (i.e. capitalize) incremental contract acquisition and fulfillment costs and recognize (or amortize) such costs over the average customer life. Our deferred contract costs for our customers have average amortization periods of approximately 30 months for consumer and up to 49 months for business. These deferred costs are monitored every period to reflect any significant change in assumptions. See Note 5—Revenue Recognition for additional information. USF Surcharges, Gross Receipts Taxes and Other Surcharges In determining whether to include in our revenue and expenses the taxes and surcharges collected from customers and remitted to government authorities, including USF surcharges, sales, use, value added and some excise taxes, we assess, among other things, whether we are the primary obligor or principal taxpayer for the taxes assessed in each jurisdiction where we do business. In jurisdictions where we determine that we are the principal taxpayer, we record the surcharges on a gross basis and include them in our revenue and costs of services and products. In jurisdictions where we determine that we are merely a collection agent for the government authority, we record the taxes on a net basis and do not include them in our revenue and costs of services and products. Advertising Costs Costs related to advertising are expensed as incurred and included in selling, general and administrative expenses in our consolidated statements of operations. Our advertising expense was $98 million , $218 million and $216 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Legal Costs In the normal course of our business, we incur costs to hire and retain external legal counsel to advise us on regulatory, litigation and other matters. We expense these costs as the related services are received. Income Taxes We file a consolidated federal income tax return with our eligible subsidiaries. The provision for income taxes consists of an amount for taxes currently payable, an amount for tax consequences deferred to future periods and adjustments to our liabilities for uncertain tax positions. We record deferred income tax assets and liabilities reflecting future tax consequences attributable to tax net operating loss carryforwards ("NOLs"), tax credit carryforwards and differences between the financial statement carrying value of assets and liabilities and the tax basis of those assets and liabilities. Deferred taxes are computed using enacted tax rates expected to apply in the year in which the differences are expected to affect taxable income. The effect on deferred income tax assets and liabilities of a change in tax rate is recognized in earnings in the period that includes the enactment date. We establish valuation allowances when necessary to reduce deferred income tax assets to the amounts that we believe are more likely than not to be recovered. Each quarter we evaluate the need to retain all or a portion of the valuation allowance on our deferred tax assets. See Note 14—Income Taxes for additional information. Cash and Cash Equivalents Cash and cash equivalents include highly liquid investments that are readily convertible into cash and are not subject to significant risk from fluctuations in interest rates. As a result, the value at which cash and cash equivalents are reported in our consolidated financial statements approximates their fair value. In evaluating investments for classification as cash equivalents, we require that individual securities have original maturities of ninety days or less and that individual investment funds have dollar-weighted average maturities of ninety days or less. To preserve capital and maintain liquidity, we invest with financial institutions we deem to be of sound financial condition and in high quality and relatively risk-free investment products. Our cash investment policy limits the concentration of investments with specific financial institutions or among certain products and includes criteria related to credit worthiness of any particular financial institution. Book overdrafts occur when checks have been issued but have not been presented to our controlled disbursement bank accounts for payment. Disbursement bank accounts allow us to delay funding of issued checks until the checks are presented for payment. Until the issued checks are presented for payment, the book overdrafts are included in accounts payable on our consolidated balance sheet. This activity is included in the operating activities section in our consolidated statements of cash flows. Restricted Cash and Securities Restricted cash and securities consists primarily of cash and investments that serve to collateralize our outstanding letters of credit and certain performance and operating obligations. Restricted cash and securities are recorded as current or non-current assets in the consolidated balance sheets depending on the duration of the restriction and the purpose for which the restriction exists. Restricted securities are stated at cost which approximates fair value as of December 31, 2018 and 2017 . Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are recognized based upon the amount due from customers for the services provided or at cost for purchased and other receivables less an allowance for doubtful accounts. The allowance for doubtful accounts receivable reflects our best estimate of probable losses inherent in our receivable portfolio determined on the basis of historical experience, specific allowances for known troubled accounts and other currently available evidence. We generally consider our accounts past due if they are outstanding over 30 days . Our collection process varies by the customer segment, amount of the receivable, and our evaluation of the customer's credit risk. Our past due accounts are written off against our allowance for doubtful accounts when collection is considered to be not probable. Any recoveries of accounts previously written off are generally recognized as a reduction in bad debt expense in the period received. The carrying value of accounts receivable net of the allowance for doubtful accounts approximates fair value. Accounts receivable balances acquired in a business combination are recorded at fair value for all balances receivable at the acquisition date and at the invoiced amount for those amounts invoiced after the acquisition date. Property, Plant and Equipment We record property, plant and equipment acquired in connection with our acquisitions based on its estimated fair value as of its acquisition date plus the estimated value of any associated legally or contractually required retirement obligations. We record purchased and constructed property, plant and equipment at cost, plus the estimated value of any associated legally or contractually required retirement obligations. The majority of our property, plant and equipment is depreciated using the straight-line group method, but certain of our assets are depreciated using the straight-line method over their estimated useful lives of the specific asset. Under the straight-line group method, assets dedicated to providing telecommunications services (which comprise the majority of our property, plant and equipment) that have similar physical characteristics, use and expected useful lives are pooled for purposes of depreciation and tracking. The equal life group procedure is used to establish each pool's average remaining useful life. Generally, under the straight-line group method, when an asset is sold or retired in the course of normal business activities, the cost is deducted from property, plant and equipment and charged to accumulated depreciation without recognition of a gain or loss. A gain or loss is recognized in our consolidated statements of operations only if a disposal is unusual. Leasehold improvements are amortized over the shorter of the useful lives of the assets or the expected lease term. Expenditures for maintenance and repairs are expensed as incurred. Interest is capitalized during the construction phase of network and other internal-use capital projects. Employee-related costs for construction of network and other internal use assets are also capitalized during the construction phase. Property, plant and equipment supplies used internally are carried at average cost, except for significant individual items for which cost is based on specific identification. We perform annual internal reviews to evaluate the reasonableness of the depreciable lives for our property, plant and equipment. Our reviews utilize models that take into account actual usage, physical wear and tear, replacement history, assumptions about technology evolution and, in certain instances, actuarially determined probabilities to estimate the remaining useful life of our asset base. Our remaining useful life assessments assess the possible loss in service value of assets that may precede the physical retirement. Assets shared among many customers may lose service value as those customers reduce their use of the asset. However, the asset is not retired until all customers no longer utilize the asset and we determine there is no alternative use for the asset. We have asset retirement obligations associated with the legally or contractually required removal of a limited group of property, plant and equipment assets from leased properties and the disposal of certain hazardous materials present in our owned properties. When an asset retirement obligation is identified, usually in association with the acquisition of the asset, we record the fair value of the obligation as a liability. The fair value of the obligation is also capitalized as property, plant and equipment and then amortized over the estimated remaining useful life of the associated asset. Where the removal obligation is not legally binding, the net cost to remove assets is expensed in the period in which the costs are actually incurred. Capitalized labor associated with employees and contract labor working on capital projects were approximately $569 million , $559 million and $524 million for the years ended December 31, 2018 , 2017 and 2016 . We review long-lived tangible assets for impairment whenever facts and circumstances indicate that the carrying amounts of the assets may not be recoverable. For assessment purposes, long-lived assets are grouped with other assets and liabilities at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities, absent a material change in operations. An impairment loss is recognized only if the carrying amount of the asset group is not recoverable and exceeds its estimated fair value. Recoverability of the asset group to be held and used is assessed by comparing the carrying amount of the asset group to the estimated undiscounted future net cash flows expected to be generated by the asset group. If the asset group's carrying value is not recoverable, we recognize an impairment charge for the amount by which the carrying amount of the asset group exceeds its estimated fair value. Goodwill, Customer Relationships and Other Intangible Assets Intangible assets arising from business combinations, such as goodwill, customer relationships, capitalized software, trademarks and trade names, are initially recorded at estimated fair value. We amortize customer relationships primarily over an estimated life of 7 to 15 years , using either the sum-of-years-digits or the straight-line methods, depending on the type of customer. We amortize capitalized software using the straight-line method over estimated lives ranging up to 7 years , except for approximately $237 million of our capitalized software costs, which represents costs to develop an integrated billing and customer care system which is amortized using the straight-line method over a 20 -year period. We amortize our other intangible assets using the sum-of-years-digits or straight-line method over an estimated life of 4 to 20 years. Other intangible assets not arising from business combinations are initially recorded at cost. Where there are no legal, regulatory, contractual or other factors that would reasonably limit the useful life of an intangible asset, we classify the intangible asset as indefinite-lived and such intangible assets are not amortized. Internally used software, whether purchased or developed by us, is capitalized and amortized using the straight-line method over its estimated useful life. We have capitalized certain costs associated with software such as costs of employees devoting time to the projects and external direct costs for materials and services. Costs associated with software to be used for internal purposes are expensed until the point at which the project has reached the development stage. Subsequent additions, modifications or upgrades to internal-use software are capitalized only to the extent that they allow the software to perform a task it previously did not perform. Software maintenance, data conversion and training costs are expensed in the period in which they are incurred. We review the remaining economic lives of our capitalized software annually. Capitalized software is included in other intangible assets, net, in our consolidated balance sheets. Our long-lived intangible assets, other than goodwill, with indefinite lives are assessed for impairment annually, or, under certain circumstances, more frequently, such as when events or changes in circumstances indicate there may be an impairment. These assets are carried at the estimated fair value at the time of acquisition and assets not acquired in acquisitions are recorded at historical cost. However, if their estimated fair value is less than the carrying amount, we recognize an impairment charge for the amount by which the carrying amount of these assets exceeds their estimated fair value. We are required to assess goodwill for impairment at least annually, or more frequently, if an event occurs or circumstances change that would indicate an impairment may have occurred. We are required to write-down the value of goodwill in periods in which the recorded carrying value of equity exceeds the fair value of equity. Our reporting units are not discrete legal entities with discrete full financial statements. Therefore, the equity carrying value and future cash flows is assessed each time a goodwill impairment assessment is performed on a reporting unit. To do so, we assign our assets, liabilities and cash flows to reporting units using reasonable and consistent allocation methodologies, which entail various estimates, judgments and assumptions. We believe these estimates, judgments and assumptions to be reasonable, but changes in any of these can significantly affect each reporting unit's equity carrying value and future cash flows utilized for our goodwill impairment assessment. We are required to reassign goodwill to reporting units each time we reorganize our internal reporting structure which causes a change in the composition of our reporting units. Goodwill is reassigned to the reporting units using a relative fair value approach. When the fair value of a reporting unit is available, we allocate goodwill based on the relative fair value of the reporting units. When fair value is not available, we utilize the earnings before interest, taxes, depreciation and amortization of each reporting unit as our allocation methodology based on our view that it represents a reasonable proxy for the fair value of the operations being reorganized. As of October 31, 2018, we assessed goodwill for impairment for our five reporting units, which we determined to be consumer, medium and small business, enterprise, international and global accounts, and wholesale and indirect. We determined that the estimated fair value of our consumer reporting unit's equity was substantially below our carrying value of equity. As a result, we recorded a non-cash, non-tax-deductible goodwill impairment charge of $2.7 billion for goodwill assigned to our consumer reporting unit during the fourth quarter of 2018. Subsequent Event As a result of organizational changes made in January 2019, we are making changes to our revenue reporting categories in 2019 to align them with how the business is managed. Our indirect channel, which primarily targets small to medium-sized enterprises, will move from the wholesale and indirect business unit. We are also moving state and local government customers from the small and medium business unit to the enterprise business unit to gain efficiencies by managing all government customers in a single organization. In addition, the new reporting structure reflects changes made to customer assignments between all five customer-facing business units. We are making changes to the service-type reporting to make it easier for management and investors to evaluate changes to consumer product revenue. We plan to report consumer revenue in the following categories: broadband; voice; regulatory (includes CAF II and other support funds); and other, which includes retail video and other miscellaneous services. We plan to maintain the structure of our business segment, with minor modifications. As a result of the organization changes noted above, we will perform a goodwill impairment analysis during the first quarter of 2019. The goodwill impairment analysis has not been completed at the time of this report and any goodwill impairment is not reasonably estimable. See Note 4—Goodwill, Customer Relationships and Other Intangible Assets for additional information. Pension and Post-Retirement Benefits We recognize the funded status of our defined benefit and post-retirement plans as an asset or a liability on our consolidated balance sheet. Each year's actuarial gains or losses are a component of our other comprehensive income (loss), which is then included in our accumulated other comprehensive loss. Pension and post-retirement benefit expenses are recognized over the period in which the employee renders service and becomes eligible to receive benefits. We make significant assumptions (including the discount rate, expected rate of return on plan assets, mortality and health care trend rates) in computing the pension and post-retirement benefits expense and obligations. Note 10—Employee Benefits for additional information. Foreign Currency Local currencies of foreign subsidiaries are the functional currencies for financial reporting purposes except for certain foreign subsidiaries, primarily in Latin America. For operations outside the United States that have functional currencies other than the U.S. dollar, assets and liabilities are translated to U.S. dollars at period-end exchange rates, and revenue, expenses and cash flows are translated using average monthly exchange rates. A significant portion of our non-United States subsidiaries have either the British pound, the euro or the Brazilian real as the functional currency, each of which experienced significant fluctuations against the U.S. dollar during the years ended December 31, 2018, 2017 and 2016. Foreign currency translation gains and losses are recognized as a component of accumulated other comprehensive loss in stockholders' equity and in the consolidated statements of comprehensive income (loss) in accordance with accounting guidance for foreign currency translation. We consider the majority of our investments in our foreign subsidiaries to be long-term in nature. Our foreign currency transaction gains (losses), including where transactions with our non-United States subsidiaries are not considered to be long-term in nature, are included within other income, net on the consolidated statements of operations. Common Stock At December 31, 2018 , we had 4 million unissued shares of CenturyLink, Inc. common stock reserved for acquisitions. In addition, we had 30 million shares authorized for future issuance under our equity incentive plans. Preferred Stock Holders of outstanding CenturyLink, Inc. preferred stock are entitled to receive cumulative dividends, receive preferential distributions equal to $25 per share plus unpaid dividends upon CenturyLink, Inc.'s liquidation and vote as a single class with the holders of common stock. Section 382 Rights Plan On February 13, 2019, we adopted a Section 382 Rights Plan to protect our U.S. federal net operating loss carryforwards from certain Internal Revenue Code Section 382 limitations. Under the plan, one preferred stock purchase right was distributed for each share of our outstanding common stock as of the close of business on February 25, 2019, and those rights currently trade in tandem with the common stock until they expire or detach under the plan. This plan was designed to deter trading that would result in a change of control (as defined in Code Section 382), and therefore protect our ability to use our historical federal net operating losses in the future. Dividends The declaration and payment of dividends is at the discretion of our Board of Directors. Recently Adopted Accounting Pronouncements During 2018, we adopted Accounting Standards Update (“ASU”) 2014-09, “ Revenue from Contracts with Customers ”, ASU 2018-02, “ Income Statement-Reporting Comprehensive Income: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income ”, ASU 2016-16, “ Intra-Entity Transfers of Assets Other Than Inventory ”, ASU 2017-04, " Simplifying the Test for Goodwill Impairment" and ASU 2018-14, " Compensation-Retirement Benefits-Defined Benefit Plans-General: Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans ". Each of these is described further below. Revenue Recognition In May 2014, the FASB issued ASU 2014-09 which replaces virtually all existing generally accepted accounting principles on revenue recognition with a principles-based approach for determining revenue recognition using a new five step model. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 also includes new accounting principles related to the deferral and amortization of contract acquisition and fulfillment costs. We adopted the new revenue recognition standard under the modified retrospective transition method. During the year ended December 31, 2018, we recorded a cumulative catch-up adjustment that increased our retained earnings by $338 million , net of $119 million of income taxes. See Note 5—Revenue Recognition for additional information. Comprehensive Loss In February 2018, the FASB issued ASU 2018-02 provides an op

Acquisition of Level 3

Acquisition of Level 3	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisition of Level 3	Acquisition of Level 3 On November 1, 2017, CenturyLink acquired Level 3 through successive merger transactions, including a merger of Level 3 with and into a merger subsidiary, which survived such merger as our indirect wholly-owned subsidiary under the name of Level 3 Parent, LLC. We entered into this acquisition to, among other things, realize certain strategic benefits, including enhanced financial and operational scale, market diversification and an enhanced combined network. As a result of the acquisition, Level 3 shareholders received $26.50 per share in cash and 1.4286 shares of CenturyLink common stock, with cash paid in lieu of fractional shares, for each outstanding share of Level 3 common stock they owned at closing, subject to certain limited exceptions. We issued this consideration with respect to all of the outstanding common stock of Level 3, with the exception of shares held by the dissenting common shareholders. Upon closing, CenturyLink shareholders owned approximately 51% and former Level 3 shareholders owned approximately 49% of the combined company. In addition, each outstanding Level 3 restricted stock unit award granted prior to April 1, 2014 or granted to an outside director of Level 3 was converted into $26.50 in cash and 1.4286 shares of CenturyLink common stock (and cash in lieu of fractional shares) with respect to each Level 3 share covered by such award (the "Converted RSU Awards"). Each outstanding Level 3 restricted stock unit award granted on or after April 1, 2014 (other than those granted to outside directors of Level 3) was converted into a CenturyLink restricted stock unit award using a conversion ratio of 2.8386 to 1 as determined in accordance with a formula set forth in the merger agreement (“the Continuing RSU Awards”). The aggregate consideration of $19.6 billion is based on: • the 517.3 million shares of CenturyLink’s common stock (including those issued in connection with the Converted RSU Awards) issued to consummate the acquisition and the closing stock price of CenturyLink common stock at October 31, 2017 of $18.99 ; • a combination of (i) the cash consideration of $26.50 per share on the 362.1 million common shares of Level 3 issued and outstanding as of October 31, 2017, (ii) the cash consideration of $1 million paid on the Converted RSUs awards; and (iii) the estimated value of $136 million the Continuing RSU Awards, which represents the pre-combination portion of Level 3’s share-based compensation awards replaced by CenturyLink; • $60 million for the dissenting common shares issued and outstanding as of October 31, 2017; and • our assumption at closing of approximately $10.6 billion of Level 3's long-term debt. The aggregate cash payments required to be paid on or about the closing date were funded with the proceeds of $7.945 billion of term loans and $400 million of funds borrowed under our new revolving credit facility together with other available funds, which included $1.825 billion borrowed from Level 3 Parent, LLC. For additional information regarding CenturyLink’s financing of the Level 3 acquisition see Note 6—Long-Term Debt and Credit Facilities . We have recognized the assets and liabilities of Level 3 based on the fair value of the acquired tangible and intangible assets and assumed liabilities of Level 3 as of November 1, 2017, the consummation date of the acquisition, with the excess aggregate consideration recorded as goodwill. The estimation of such fair values and the estimation of lives of depreciable tangible assets and amortizable intangible assets required significant judgment. We completed our final fair value determination during the fourth quarter of 2018. Our final fair value determinations were different than those reflected in our consolidated financial statements at December 31, 2017 . In connection with receiving approval from the U.S. Department of Justice to complete the Level 3 acquisition we agreed to divest (i) certain Level 3 network assets in three metropolitan areas and (ii) 24 strands of dark fiber connecting 30 specified city-pairs across the United States. All of the metro network assets were classified as assets held for sale on our consolidated balance sheet as of December 31, 2017. All of those assets were sold by December 31, 2018 . The proceeds from these sales were included in the proceeds from sale of property, plant and equipment in our consolidated statements of cash flows. No gain or loss was recognized with these transactions. As of October 31, 2018, the aggregate consideration exceeds the aggregate estimated fair value of the acquired assets and assumed liabilities by $11.2 billion , which we have recognized as goodwill. The goodwill is attributable to strategic benefits, including enhanced financial and operational scale, market diversification and leveraged combined networks that we expect to realize. None of the goodwill associated with this acquisition is deductible for income tax purposes. The following is our assignment of the aggregate consideration: Adjusted November 1, 2017 Balance as of December 31, 2017 Purchase Price Adjustments Adjusted November 1, 2017 Balance as of October 31, 2018 (Dollars in millions) Cash, accounts receivable and other current assets (1) $ 3,317 (26 ) 3,291 Property, plant and equipment 9,311 157 9,468 Identifiable intangible assets (2) Customer relationships 8,964 (533 ) 8,431 Other 391 (13 ) 378 Other noncurrent assets 782 216 998 Current liabilities, excluding current maturities of long-term debt (1,461 ) (32 ) (1,493 ) Current maturities of long-term debt (7 ) — (7 ) Long-term debt (10,888 ) — (10,888 ) Deferred revenue and other liabilities (1,629 ) (114 ) (1,743 ) Goodwill 10,837 340 11,177 Total estimated aggregate consideration $ 19,617 (5 ) 19,612 ____________________________________________________________________________________________________________ (1) Includes accounts receivable, which had a gross contractual value of $884 million on November 1, 2017 and October 31, 2018. (2) The weighted-average amortization period for the acquired intangible assets is approximately 12.0 years . On the acquisition date, we assumed Level 3’s contingencies. For more information on our contingencies, see Note 17—Commitments, Contingencies and Other Items . Acquisition-Related Expenses We have incurred acquisition-related expenses related to our acquisition of Level 3. The table below summarizes our acquisition-related expenses, which consist of integration-related expenses, including severance and retention compensation expenses, and transaction-related expenses: Years Ended December 31, 2018 2017 (Dollars in millions) Transaction-related expenses $ 2 174 Integration-related expenses 391 97 Total acquisition-related expenses $ 393 271 At December 31, 2018 , we had incurred cumulative acquisition-related expenses of $716 million for Level 3. The total amounts of these expenses are included in our selling, general and administrative expenses. Level 3 incurred transaction-related expenses of $47 million on the date of acquisition. This amount is not included in our results of operations.

Sale of Data Centers and Coloca

Sale of Data Centers and Colocation Business	12 Months Ended
	Dec. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Sale of Data Centers and Colocation Business	Sale of Data Centers and Colocation Business On May 1, 2017, we sold our data centers and colocation business to a consortium led by BC Partners, Inc. and Medina Capital in exchange for cash and a minority stake in the limited partnership that owns the consortium's newly-formed global secure infrastructure company, Cyxtera Technologies ("Cyxtera"). At the closing of this sale, we received pre-tax cash proceeds of $1.8 billion , and we valued our minority stake at $150 million , which was based upon the total amount of equity contributions to the limited partnership on the date made. Due to the sale and related restructuring actions we have taken regarding certain subsidiaries involved in the data centers and colocation business, we have estimated a cumulative current tax impact relating to the sale totaling $65 million , $18 million of which was accrued in 2016 and $47 million of which was accrued in 2017. In connection with our sale of the data centers and colocation business to Cyxtera, we agreed to lease back from Cyxtera a portion of the data center space to provide data hosting services to our customers. Because we have continuing involvement in the business through our minority stake in Cyxtera's parent, we did not meet the requirements for a sale-leaseback transaction as described in ASC 840-40, Leases - Sale-Leaseback Transactions . Under the failed-sale-leaseback accounting model, we were deemed under GAAP to still own certain real estate assets sold to Cyxtera, which we continued to reflect on our consolidated balance sheet and depreciate over the assets' remaining useful life. We also treated a certain amount of the pre-tax cash proceeds from the sale of the assets as though it were the result of a financing obligation on our consolidated balance sheet, and our consolidated results of operations included imputed revenue associated with the portion of the real estate assets that we did not lease back and imputed interest expense on the financing obligation. A portion of the rent payments under our leaseback arrangement with Cyxtera were recognized as a reduction of the financing obligation, resulting in lower recognized rent expense than the amounts actually paid each period. The following table reflects the assets sold to and the liabilities assumed by Cyxtera on May 1, 2017, including the impact of failed-sale-leaseback: Dollars in millions Goodwill $ 1,142 Property, plant and equipment 1,051 Other intangible assets 249 Other assets 66 Less assets not removed as a result of the failed-sale-leaseback (526 ) Total net amount of assets derecognized $ 1,982 Capital lease obligations $ 294 Other liabilities 274 Less imputed financing obligations from the failed-sale-leaseback (628 ) Total net imputed liabilities recognized $ (60 ) In addition, the failed-sale-leaseback accounting treatment had the following effects on our consolidated results of operations for the years ended December 31, 2018 and 2017 : Positive (Negative) Impact to Net Income December 31, 2018 2017 (Dollars in millions) Increase in revenue $ 74 49 Decrease in cost of sales 22 15 Increase in loss on sale of business included in selling, general and administrative expense — (102 ) Increase in depreciation expense (one-time) — (44 ) Increase in depreciation expense (ongoing) (69 ) (47 ) Increase in interest expense (55 ) (39 ) Decrease in income tax expense 7 65 Decrease in net income $ (21 ) (103 ) After factoring in the costs to sell the data centers and colocation business, excluding the impact from the failed-sale-leaseback accounting treatment, the sale resulted in a $20 million gain as a result of the aggregate value of the proceeds we received exceeding the carrying value of the assets sold and liabilities assumed. Based on the fair market values of the failed-sale-leaseback assets, the failed-sale-leaseback accounting treatment resulted in a loss of $102 million as a result of the requirement to treat a certain amount of the pre-tax cash proceeds from the sale of the assets as though it were the result of a financing obligation. The combined net loss of $82 million was included in selling, general and administrative expenses in our consolidated statement of operations for the year ended December 31, 2017. The sale also resulted in a significant capital loss carryforward, which was entirely offset by a valuation allowance due to our determination that we are not likely to be able to utilize this carryforward prior to its expiration. We evaluated our minority stake in the limited partnership and determined that we were not the primary beneficiary of the entity. As a result, we classified our $150 million investment in the limited partnership in other assets on our consolidated balance sheet as of December 31, 2018 and 2017 . In addition to our investment, we have a $3 million payable to Cyxtera, classified in other accrued liabilities on our consolidated balance sheet as of December 31, 2018 . We had a receivable for $10 million and $49 million , classified in other current assets on our consolidated balance sheet as of December 31, 2018 and 2017, respectively as a result of amounts charged for the lease of data center space. We will continue to have an ongoing obligation to Cyxtera related to our lease of data center space from them. During the year ended December 31, 2018, we paid rent to Cyxtera totaling $132 million . From May 1, 2017 through December 31, 2017, we paid rent to Cyxtera totaling $80 million . Effective November 3, 2016, which is the date we entered into the agreement to sell our data centers and colocation business, we ceased recording depreciation of the property, plant and equipment to be sold and amortization of the business's intangible assets in accordance with applicable accounting rules. Otherwise, we estimate that we would have recorded additional depreciation and amortization expense of $67 million from January 1, 2017 through May 1, 2017. Upon adopting ASU 2016-02, accounting for the failed sale leaseback will no longer be applicable based on our facts and circumstances, and the real estate assets and corresponding financing obligation will be derecognized from our consolidated financial statements. Please see "Leases" (ASU 2016-02) in Note 1— Background and Summary of Significant Accounting Policies for additional information on the impact the new lease standard will have on the accounting for the failed-sale-leaseback.

Goodwill, Customer Relationship

Goodwill, Customer Relationships and Other Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Customer Relationships and Other Intangible Assets	Goodwill, Customer Relationships and Other Intangible Assets Goodwill, customer relationships and other intangible assets consisted of the following: As of December 31, 2018 2017 (Dollars in millions) Goodwill $ 28,031 30,475 Customer relationships, less accumulated amortization of $8,492 and $7,096 $ 8,911 10,876 Indefinite-life intangible assets $ 269 269 Other intangible assets subject to amortization: Capitalized software, less accumulated amortization of $2,616 and $2,294 $ 1,468 1,469 Trade names, less accumulated amortization of $61 and $31 131 159 Total other intangible assets, net $ 1,868 1,897 Our goodwill was derived from numerous acquisitions where the purchase price exceeded the fair value of the net assets acquired (including the acquisition described in Note 2—Acquisition of Level 3 ). At December 31, 2018 , the net carrying amounts of goodwill, customer relationships and other intangibles assets included $19.1 billion as a result of our Level 3 acquisition. As of December 31, 2018 , the weighted average remaining useful lives of the intangible assets acquired in the acquisition of Level 3 was approximately 11 years in total, approximately 11 years for customer relationships, 3 years for capitalized software and 4 years for trade names. Total amortization expense for intangible assets for the years ended December 31, 2018 , 2017 and 2016 was $1.8 billion , $1.2 billion and $1.2 billion , respectively. As of December 31, 2018 , the gross carrying amount of goodwill, customer relationships, indefinite-life and other intangible assets was $50.0 billion . We estimate that total amortization expense for intangible assets for the years ending December 31, 2019 through 2023 will be as follows: (Dollars in millions) 2019 $ 1,691 2020 1,589 2021 1,156 2022 985 2023 893 We assess our goodwill and other indefinite-lived intangible assets for impairment annually, or, under certain circumstances, more frequently, such as when events or changes in circumstances indicate there may be impairment. We are required to write down the value of goodwill only when our assessment determines the recorded amount of goodwill exceeds the fair value. Our annual impairment assessment date for goodwill is October 31, at which date we assessed our reporting units, which were consumer, medium and small business, enterprise, international and global accounts, and wholesale and indirect. Our annual impairment assessment date for indefinite-lived intangible assets other than goodwill is December 31. Our reporting units are not discrete legal entities with discrete full financial statements. Our assets and liabilities are employed in and relate to the operations of multiple reporting units. For each reporting unit, we compare its estimated fair value of equity to its carrying value of equity that we assign to the reporting unit. If the estimated fair value of the reporting unit is greater than the carrying value, we conclude that no impairment exists. If the estimated fair value of the reporting unit is less than the carrying value, we record an impairment equal to the excess amount. At October 31, 2018, we estimated the fair value of our five above-mentioned reporting units by considering both a market approach and a discounted cash flow method. The market approach method includes the use of comparable multiples of publicly traded companies whose services are comparable to ours. The discounted cash flow method is based on the present value of projected cash flows and a terminal value, which represents the expected normalized cash flows of the reporting units beyond the cash flows from the discrete projection period. We reconciled the estimated fair values of the reporting units to our market capitalization as of October 31, 2018 and concluded that the indicated control premium of approximately 0.1% was reasonable based on recent transactions in the market place. As of October 31, 2018, based on our assessment performed with respect to these reporting units as described above, we concluded that the estimated fair value of our consumer reporting unit was less than our carrying value of equity by approximately $2.7 billion . As a result, we recorded a non-cash, non-tax-deductible goodwill impairment charge of $2.7 billion for goodwill assigned to our consumer reporting unit during the fourth quarter of 2018. In addition, based on our assessments performed, we concluded that the goodwill for our four remaining reporting units was not impaired as of October 31, 2018. As of October 31, 2018, based on our assessment performed with respect to our four reporting units included in our business segment, the estimated fair value of our equity exceeded our carrying value of equity for our medium and small business, enterprise, international and global accounts and wholesale and indirect by 2% , 11% , 30% and 5% , respectively. After the impairment charge described above, the estimated fair value of equity for our consumer reporting unit equals the carrying value of equity for such unit. As of October 31, 2017, based on our assessments performed, we concluded that our goodwill for our then three reporting units was not impaired as of this date. We completed our qualitative assessment of our indefinite-lived intangible assets other than goodwill as of December 31, 2018 and 2017 and concluded it is more likely than not that our indefinite-lived intangible assets are not impaired; thus, no impairment charge was recorded in 2018 or 2017. The following table shows the rollforward of goodwill assigned to our reportable segments from December 31, 2016 through December 31, 2018 . Business Consumer Total (Dollars in millions) As of December 31, 2016 (1) $ 9,372 10,278 19,650 Purchase accounting and other adjustments 10,825 — 10,825 As of December 31, 2017 (1) 20,197 10,278 30,475 Purchase accounting and other adjustments (2)(3) 250 32 282 Impairment — (2,726 ) (2,726 ) As of December 31, 2018 $ 20,447 7,584 $ 28,031 _____________________________________________________________________________ (1) Goodwill is net of accumulated impairment losses of $1.1 billion that related to our former hosting segment now included in our business segment. (2) We allocated $32 million of Level 3 goodwill to consumer as we expect the consumer segment to benefit from synergies resulting from the business combination. (3) Includes $58 million decrease due to effect of foreign currency exchange rate change. As of December 31, 2018 , our goodwill has been allocated to our reporting units as follows: (Dollars in millions) Medium and small business $ 5,193 Enterprise 5,222 International and global accounts 3,596 Wholesale and indirect 6,436 Total business segment 20,447 Consumer 7,584 Total goodwill $ 28,031 For additional information on our segments, see Note 15—Segment Information .

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition Comparative Results The following tables present our reported results under ASC 606 and a reconciliation to results using the historical accounting method: Year Ended December 31, 2018 Reported Balances Impact of ASC 606 ASC 605 Historical Adjusted Balances (Dollars in millions, except per share amounts and shares in thousands) Operating revenue $ 23,443 39 23,482 Cost of services and products (exclusive of depreciation and amortization) 10,862 22 10,884 Selling, general and administrative 4,165 71 4,236 Interest expense 2,177 (9 ) 2,168 Income tax expense 170 (12 ) 158 Net loss (1,733 ) (33 ) (1,766 ) BASIC AND DILUTED LOSS PER COMMON SHARE BASIC $ (1.63 ) (0.03 ) (1.66 ) DILUTED $ (1.63 ) (0.03 ) (1.66 ) WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING BASIC 1,065,866 — 1,065,866 DILUTED 1,065,866 — 1,065,866 The following table presents a reconciliation of certain consolidated balance sheet captions under ASC 606 to the balance sheet results using the historical accounting method: As of December 31, 2018 Reported Balances Impact of ASC 606 ASC 605 Historical Adjusted Balances (Dollars in millions) Other current assets $ 918 (172 ) 746 Other long-term assets, net 1,060 (112 ) 948 Deferred revenue 2,375 71 2,446 Deferred income taxes, net 2,395 (131 ) 2,264 Other long-term liabilities 1,099 147 1,246 Accumulated deficit (1,643 ) (371 ) (2,014 ) Disaggregated Revenue by Service Offering The following tables provide disaggregation of revenue from contracts with customers based on service offerings for the year ended December 31, 2018, respectively. It also shows the amount of revenue that is not subject to ASC 606, but is instead governed by other accounting standards. Year Ended December 31, 2018 Total Revenue Adjustments for Non-ASC 606 Revenue (8) Total Revenue from Contracts with Customers (Dollars in millions) Business segment IP and Data Services (1) $ 6,971 — 6,971 Transport and Infrastructure (2) 5,356 (569 ) 4,787 Voice and Collaboration (3) 4,401 — 4,401 IT and Managed Services (4) 621 — 621 Total business segment revenue 17,349 (569 ) 16,780 Consumer segment IP and Data Services (5) 308 (33 ) 275 Transport and Infrastructure (6) 2,892 (213 ) 2,679 Voice and Collaboration (3) 2,171 — 2,171 Total consumer segment revenue 5,371 (246 ) 5,125 Non-segment revenue Regulatory Revenue (7) 723 (723 ) — Total non-segment revenue 723 (723 ) — Total revenue $ 23,443 (1,538 ) 21,905 Timing of Revenue Goods and services transferred at a point in time $ 230 Services performed over time 21,675 Total revenue from contracts with customers $ 21,905 (1 ) Includes primarily VPN data network, Ethernet, IP, video and ancillary revenue. (2 ) Includes primarily broadband, private line (including business data services), colocation and data centers, wavelength and ancillary revenue. (3 ) Includes local, long-distance and other ancillary revenue. (4 ) Includes IT services and managed services revenue. (5 ) Includes retail video revenue (including our facilities-based video revenue). (6 ) Includes primarily broadband and equipment sales and professional services revenue. (7 ) Includes CAF Phase I, CAF Phase II, federal and state USF support revenue, sublease rental income and failed-sale leaseback income. (8 ) Includes regulatory revenue, lease revenue, sublease rental income, revenue from fiber capacity lease arrangements and failed sale leaseback income, which are not within the scope of ASC 606. Customer Receivables and Contract Balances The following table provides balances of customer receivables, contract assets and contract liabilities as of December 31, 2018 and January 1, 2018: December 31, 2018 January 1, 2018 (Dollars in millions) Customer receivables (1) $ 2,346 2,504 Contract liabilities 860 904 Contract assets 140 145 (1 ) Gross customer receivables of $2.5 billion and $2.7 billion, net of allowance for doubtful accounts of $132 million and $155 million, at December 31, 2018 and January 1, 2018, respectively. Contract liabilities are consideration we have received from our customers or billed in advance of providing goods or services promised in the future. We defer recognizing this consideration as revenue until we have satisfied the related performance obligation to the customer. Contract liabilities include recurring services billed one month in advance and installation and maintenance charges that are deferred and recognized over the actual or expected contract term, which ranges from one to seven years depending on the service. Contract liabilities are included within deferred revenue in our consolidated balance sheet. The following table provides information about revenue recognized for the year ended December 31, 2018 : (Dollars in millions) Revenue recognized in the period from: Amounts included in contract liability at the beginning of the period (January 1, 2018) $ 295 Performance obligations satisfied in previous periods — Performance Obligations As of December 31, 2018 , our estimated revenue expected to be recognized in the future related to performance obligations associated with customer contracts that are unsatisfied (or partially satisfied) is approximately $6.9 billion . We expect to recognize approximately 83% of this revenue through 2021, with the balance recognized thereafter. We do not disclose the value of unsatisfied performance obligations for contracts for which we recognize revenue at the amount to which we have the right to invoice for services performed (for example, uncommitted usage or non-recurring charges associated with professional or technical services to be completed), or contracts that are classified as leasing arrangements that are not subject to ASC 606. Contract Costs The following table provides changes in our contract acquisition costs and fulfillment costs: Year Ended December 31, 2018 Acquisition Costs Fulfillment Costs (Dollars in millions) Beginning of period balance $ 268 133 Costs incurred 226 146 Amortization (172 ) (92 ) End of period balance $ 322 187 Acquisition costs include commission fees paid to employees as a result of obtaining contracts. Fulfillment costs include third party and internal costs associated with the provision, installation and activation of telecommunications services to customers, including labor and materials consumed for these activities. Deferred acquisition and fulfillment costs are amortized based on the transfer of services on a straight-line basis over the average customer life of 30 months for consumer customers and 12 to 60 months for business customers and amortized fulfillment costs are included in cost of services and products and amortized acquisition costs are included in selling, general and administrative expenses in our consolidated statement of operations. The amount of these deferred costs that are anticipated to be amortized in the next twelve months are included in other current assets on our consolidated balance sheets. The amount of deferred costs expected to be amortized beyond the next twelve months is included in other non-current assets on our consolidated balance sheets. Deferred acquisition and fulfillment costs are assessed for impairment on an annual basis.

Long-Term Debt and Credit Facil

Long-Term Debt and Credit Facilities	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Long-Term Debt and Credit Facilities	Long-Term Debt and Credit Facilities The following chart reflects the consolidated long-term debt of CenturyLink, Inc. and its subsidiaries, including unamortized discounts and premiums and unamortized debt issuance costs, but excluding intercompany debt: As of December 31, Interest Rates (1) Maturities 2018 2017 (Dollars in millions) Senior Secured Debt: (2) CenturyLink, Inc. 2017 Revolving Credit Facility (3) 5.130% - 7.250% 2022 $ 550 405 Term Loan A 5.272% 2022 1,622 1,575 Term Loan A-1 5.272% 2022 351 370 Term Loan B 5.272% 2025 5,940 6,000 Subsidiaries: Level 3 Financing, Inc. Tranche B 2024 Term Loan (4) 4.754% 2024 4,611 4,611 Embarq Corporation subsidiaries First mortgage bonds 7.125% - 8.375% 2023 - 2025 138 151 Senior Notes and Other Debt: CenturyLink, Inc. Senior notes 5.625% - 7.650% 2019 - 2042 8,036 8,125 Subsidiaries: Level 3 Financing, Inc. Senior notes 5.125% - 6.125% 2021 - 2026 5,315 5,315 Level 3 Parent, LLC Senior notes 5.750% 2022 600 600 Qwest Corporation Senior notes 6.125% - 7.750% 2021 - 2057 5,956 7,294 Term loan 4.530% 2025 100 100 Qwest Capital Funding, Inc. Senior notes 6.875% - 7.750% 2021 - 2031 697 981 Embarq Corporation and subsidiary Senior note 7.995% 2036 1,485 1,485 Other 9.000% 2019 150 150 Capital lease and other obligations Various Various 801 891 Unamortized (discounts) premiums and other, net (8 ) 23 Unamortized debt issuance costs (283 ) (350 ) Total long-term debt 36,061 37,726 Less current maturities (652 ) (443 ) Long-term debt, excluding current maturities $ 35,409 37,283 _______________________________________________________________________________ (1) As of December 31, 2018 . (2) See the remainder of this Note for a description of certain parent or subsidiary guarantees and liens securing this debt. (3) The aggregate amount outstanding on our 2017 revolving credit facility at December 31, 2018 was $550 million with a weighted-average interest rate of 5.322% . These amounts typically change on a regular basis. (4) The Tranche B 2024 Term Loan had an interest rate of 4.754% as of December 31, 2018 and 3.557% as of December 31, 2017 . Debt of CenturyLink, Inc. and its Subsidiaries At December 31, 2018 , most of our outstanding consolidated debt had been incurred by CenturyLink, Inc. or one of the following four other primary borrowers or “borrowing groups,” each of which has borrowed funds either on a standalone basis or as part of a separate restricted group with certain of its subsidiaries: • Qwest Corporation; • Qwest Capital Funding, Inc. (including its parent guarantor, Qwest Communications International Inc.); • Embarq Corporation; and • Level 3 Parent, LLC (including its finance subsidiary, Level 3 Financing, Inc.). Each of these borrowers or borrowing groups has entered into one or more credit agreements with certain financial institutions or other institutional lenders, or issued senior notes. Certain of these debt instruments are described further below. 2017 CenturyLink Credit Agreement In connection with financing its acquisition of Level 3 on November 1, 2017, CenturyLink, Inc. caused its wholly-owned subsidiary, CenturyLink Escrow, LLC, to enter into a credit agreement on June 19, 2017 (the "2017 CenturyLink Credit Agreement") with, among others, Bank of America, N.A., as administrative agent and collateral agent, currently providing for $10.245 billion in senior secured credit facilities (the "2017 Senior Secured Credit Facilities"). As amended in early 2018, these facilities currently consist of the following: • a $2.168 billion revolving credit facility (“2017 Revolving Credit Facility”), with 18 lenders, each with allocations ranging from $36.4 million to $167.8 million ; • a $1.707 billion senior secured Term Loan A credit facility, with 18 lenders, each with commitments ranging from $28.6 million to $132.2 million ; • a $370 million senior secured Term Loan A-1 credit facility with CoBank, ACB; and • a $6.0 billion senior secured Term Loan “B” credit facility, the proceeds of which were fully pre-funded to us, net of a discount, into escrow on June 19, 2017 and released to us on November 1, 2017. Loans under the Term Loan A and A-1 facilities and the 2017 Revolving Credit Facility bear interest at a rate equal to, at our option, the London Interbank Offered Rate (“LIBOR”) or the alternative base rate (each as defined in the 2017 CenturyLink Credit Agreement) plus an applicable margin between 2.25% to 3.00% per annum for LIBOR loans and 1.25% to 2.00% per annum for alternative base rate loans, depending on our then current total leverage ratio. Borrowings under the Term Loan B facility bore interest at 1.375% per annum through July 18, 2017 and at 2.75% per annum thereafter through November 1, 2017. Subsequent to November 1, 2017, borrowings under the Term Loan B facility have borne interest at LIBOR plus 2.75% per annum. Loans under each of the term loan facilities require certain specified quarterly amortization payments and certain specified mandatory prepayments in connection with certain asset sales and debt issuances and out of excess cash flow, among other things, subject in each case to certain significant exceptions. The 2017 Revolving Credit Facility and borrowings under the Term Loan A and A-1 facilities will mature on November 1, 2022. Borrowings under the Term Loan B facility will mature on January 31, 2025. On November 1, 2017, CenturyLink, Inc. assumed all rights and obligations under the 2017 CenturyLink Credit Agreement, including the right to borrow funds under the 2017 Revolving Credit Facility on the terms and conditions specified in the 2017 CenturyLink Credit Agreement. All of CenturyLink, Inc.'s obligations under the 2017 Senior Secured Credit Facilities are guaranteed by certain of its subsidiaries. The guarantees by certain of those guarantors are secured by a first priority security interest in substantially all assets (including certain subsidiaries stock) directly owned by them, subject to certain exceptions and limitations. A portion of the 2017 Revolving Credit Facility in an amount not to exceed $100 million is available for swingline loans, and a portion in an amount not to exceed $400 million is available for the issuance of letters of credit. CenturyLink, Inc. is permitted under the 2017 CenturyLink Credit Agreement to request certain incremental borrowings subject to the satisfaction of various conditions and to certain other limitations. Any incremental borrowings would be subject to the same terms and conditions under the 2017 CenturyLink Credit Agreement. Term Loans and Certain Other Debt of Subsidiaries Qwest Corporation In 2015, Qwest Corporation entered into a term loan in the amount of $100 million with CoBank, ACB. The outstanding unpaid principal amount of this term loan plus any accrued and unpaid interest is due on February 20, 2025. Interest is paid at least quarterly based upon either the London Interbank Offered Rate (“LIBOR”) or the base rate (as defined in the credit agreement) plus an applicable margin between 1.50% to 2.50% per annum for LIBOR loans and 0.50% to 1.50% per annum for base rate loans depending on Qwest Corporation's then current senior unsecured long-term debt rating. At both December 31, 2018 and 2017, the outstanding principal balance on this term loan was $100 million . Level 3 Financing, Inc . At December 31, 2018 and 2017, Level 3 Financing, Inc. owed $4.611 billion under the Tranche B 2024 Term Loan, which matures on February 22, 2024. The Tranche B 2024 Term Loan carries an interest rate, in the case of base rate borrowings, equal to (i) the greater of the Prime Rate, the Federal Funds Effective Rate plus 50 basis points, or LIBOR plus 100 basis points (with all such terms and calculations as defined or further specified in the applicable credit agreement) plus (ii) 1.25% per annum. Any Eurodollar borrowings under the Tranche B 2024 Term Loan bear interest at LIBOR plus 2.25% per annum. The Tranche B 2024 Term Loan requires certain specified mandatory prepayments in connection with certain asset sales and other transactions, subject to certain significant exceptions. The obligations of Level 3 Financing, Inc. under the Tranche B 2024 Term Loan are, subject to certain exceptions, secured by certain assets of Level 3 Parent, LLC and certain of its material domestic telecommunication subsidiaries. Also, Level 3 Parent, LLC and certain of its subsidiaries have guaranteed the obligations of Level 3 Financing, Inc. under the Tranche B 2024 Term Loan. Level 3 Communications, LLC and its material domestic subsidiaries guarantee and pledge certain of their assets to secure the obligations of Level 3 Financing, Inc. under the Tranche B 2024 Term Loan. Embarq Subsidiaries At December 31, 2018 and 2017, one of our Embarq subsidiaries had outstanding first mortgage bonds. This first mortgage bond is secured by substantially all of the property, plant and equipment of the issuing subsidiary. Revolving Letters of Credit We use various financial instruments in the normal course of business. These instruments include letters of credit, which are conditional commitments issued on our behalf in accordance with specified terms and conditions. CenturyLink, Inc. maintains an uncommitted $225 million revolving letter of credit facility separate from the letter of credit facility included in the 2017 Revolving Credit Facility noted above. Letters of credit issued under this facility are backed by credit enhancements in the form of secured guarantees issued by certain CenturyLink subsidiaries. As of December 31, 2018 and 2017, CenturyLink, Inc.’s outstanding letters of credit under this credit facility totaled $97 million and $104 million , respectively. As of December 31, 2018 , Level 3 Parent, LLC had outstanding letters of credit or other similar obligations of approximately $30 million of which $24 million is collateralized by cash that is reflected on the consolidated balance sheets in restricted cash and securities. As of December 31, 2017, Level 3 Parent, LLC had outstanding letters of credit or other similar obligations of approximately $36 million of which $30 million is collateralized by cash that is reflected on the consolidated balance sheets in restricted cash and securities. Senior Notes CenturyLink, Inc., Level 3 Financing, Inc., Level 3 Parent, LLC, Qwest Corporation, Qwest Capital Funding, Inc. and Embarq Corporation have each issued unsecured senior notes. All of these notes carry fixed interest rates and all principal is due on the notes’ respective maturity dates, which rates and maturity dates are summarized in the table above. The senior notes issued by Level 3 Financing, Inc. are guaranteed by its parent, Level 3 Parent, LLC and another of its affiliates. The senior notes issued by Qwest Capital Funding, Inc. are guaranteed by its parent, Qwest Communications International Inc. Except for a limited number of senior notes issued by Qwest Corporation, the issuer generally can redeem the notes, at its option, in whole or in part, (i) pursuant to a fixed schedule of pre-established redemption prices, (ii) pursuant to a “make whole” redemption price or (iii) under certain other specified limited conditions. Under certain circumstances in connection with a “change of control” of CenturyLink, Inc., it will be required to make an offer to repurchase each series of these senior notes (other than two of its older series of notes) at a price of 101% of the principal amount redeemed, plus accrued and unpaid interest. Also, under certain circumstances in connection with a "change of control" of Level 3 Parent, LLC, it, as well as Level 3 Financing, Inc., will be required to make an offer to repurchase each series of its outstanding senior notes at a price of 101% of the principal amount redeemed, plus accrued and unpaid interest. New Issuances As described above under “2017 CenturyLink Credit Agreement”, on June 19, 2017, CenturyLink, Inc. caused one of its wholly-owned subsidiaries to enter into the 2017 CenturyLink Credit Agreement currently providing for $10.2 billion of senior secured credit facilities. Upon the execution of the 2017 CenturyLink Credit Agreement, the $6.0 billion Term Loan B credit facility was fully funded. On November 1, 2017, CenturyLink, Inc. assumed the obligations and borrowed additional sums under such credit agreement. On April 27, 2017 , Qwest Corporation issued $575 million aggregate principal amount of 6.75% Notes due 2057 and, on May 5, 2017, issued an additional $85 million aggregate principal amount of such notes pursuant to an over-allotment option in exchange for aggregate net proceeds, after deducting underwriting discounts and other expenses, of $638 million . All of the 6.75% Notes are senior unsecured obligations and may be redeemed by Qwest Corporation, in whole or in part, on or after June 15, 2022, at a redemption price equal to 100% of the principal amount redeemed plus accrued and unpaid interest to the redemption date. Repayments 2018 During 2018, CenturyLink and its affiliates redeemed approximately $1.7 billion in debt securities, which primarily included approximately $174 million of Qwest Capital Financing 6.5% Notes due 2018, approximately $164 million of Qwest Corporation 7.5% Notes due 2051, approximately $925 million of Qwest Corporation 7.0% Notes due 2052 and approximately $250 million of Qwest 7.25% Notes due 2035. 2017 As described above under “2017 CenturyLink Credit Agreement”, on November 1, 2017, CenturyLink, Inc. repaid the outstanding principal amount of $319 million under its 2012 term loan. During 2017, subsidiaries of Embarq Corporation paid at maturity the $72 million principal amount and accrued and unpaid interest due under their 8.77% Notes. CenturyLink, Inc. paid at maturity the $350 million principal and accrued and unpaid interest due under its 5.15% Notes. Qwest Corporation redeemed $125 million aggregate principal amount of the remaining $288 million of its 7.5% Notes due 2051. Qwest Corporation redeemed all $500 million of its 6.5% Notes due 2017. CenturyLink, Inc. paid at maturity the $500 million principal and accrued and unpaid interest due under its 6.00% Notes. Long-Term Debt Maturities Set forth below is the aggregate principal amount of our long-term debt (excluding unamortized discounts and premiums, net and unamortized debt issuance costs) maturing during the following years: (Dollars in millions) (1) 2019 $ 652 2020 1,205 2021 3,115 2022 5,283 2023 2,096 2024 and thereafter 23,503 Total long-term debt $ 35,854 _______________________________________________________________________________ (1) In Note 3—Sale of Data Centers and Colocation Business, we describe an imputed financing obligation. The amount outstanding on that imputed financing obligation at December 31, 2018 was $558 million . The aggregate maturities of long-term debt do not include $499 million of this obligation, which prior to the end of the lease term on April 30, 2020, will be derecognized along with the remaining net book value of the associated real estate assets. Interest Expense Interest expense includes interest on total long-term debt. The following table presents the amount of gross interest expense, net of capitalized interest: Years Ended December 31, 2018 2017 2016 (Dollars in millions) Interest expense: Gross interest expense $ 2,230 1,559 1,372 Capitalized interest (53 ) (78 ) (54 ) Total interest expense $ 2,177 1,481 1,318 Covenants CenturyLink, Inc. With respect to the Term Loan A and A-1 facilities and the 2017 Revolving Credit Facility, the 2017 CenturyLink Credit Agreement requires us to maintain (i) a maximum total leverage ratio of not more than 5.00 to 1.00 until November 1, 2019 and 4.75 to 1.00 thereafter and (ii) a minimum consolidated interest coverage ratio of at least 2.00 to 1.00, with such ratios being determined and calculated in the manner described in the 2017 CenturyLink Credit Agreement. The 2017 Senior Secured Credit Facilities contain various representations and warranties and extensive affirmative and negative covenants. Such covenants include, among other things and subject to certain significant exceptions, restrictions on our ability to declare or pay dividends, repurchase stock, repay certain other indebtedness, create liens, incur additional indebtedness, make investments, engage in transactions with its affiliates, dispose of assets and merge or consolidate with any other person. The senior notes of CenturyLink, Inc. were issued under an indenture dated March 31, 1994. This indenture restricts our ability to (i) incur, issue or create liens upon the property of CenturyLink, Inc. and (ii) consolidate with or merge into, or transfer or lease all or substantially all of our assets to any other party. The indenture does not contain any provisions that are impacted by our credit ratings or that restrict the issuance of new securities in the event of a material adverse change to us. However, as indicated above under "Senior Notes", CenturyLink, Inc. will be required to offer to purchase certain of its long-term debt securities issued under this indenture under certain circumstances in connection with a "change of control" of CenturyLink, Inc. Level 3 Companies The term loan and senior notes of Level 3 Parent, LLC and Level 3 Financing, Inc. contain various representations and extensive affirmative and negative covenants. Such covenants include, among other things and subject to certain significant exceptions, restrictions on their ability to declare or pay dividends, repay certain other indebtedness, create liens, incur additional indebtedness, make investments, engage in transactions with their affiliates, dispose of assets and merge or consolidate with any other person. Also, as indicated above under "Senior Notes", Level 3 Parent, LLC, as well as Level 3 Financing, Inc., will be required to offer to purchase certain of its long-term debt securities under certain circumstances in connection with a "change of control" of Level 3 Parent, LLC. Qwest Companies Under its term loan, Qwest Corporation must maintain a debt to EBITDA (earnings before interest, taxes, depreciation and amortization, as defined in such term loan documentation) ratio of not more than 2.85 :1.0, as of the last day of each fiscal quarter for the four quarters then ended. The term loan also contains a negative pledge covenant, which generally requires Qwest Corporation to secure equally and ratably any advances under the term loan if it pledges assets or permit liens on its property for the benefit of other debtholders. The senior notes of Qwest Corporation were issued under indentures dated April 15, 1990 and October 15, 1999. These indentures contain restrictions on the incurrence of liens and the consummation of certain transactions substantially similar to the above-described covenants in CenturyLink, Inc.'s March 31, 1994 indenture (but contain no mandatory repurchase provisions). The senior notes of Qwest Capital Funding, Inc. were issued under an indenture dated June 29, 1998 containing terms substantially similar to those set forth in Qwest Corporation's indentures. Embarq Embarq's senior note was issued pursuant to an indenture dated as of May 17, 2006. While Embarq is generally prohibited from creating liens on its property unless its senior notes are secured equally and ratably, Embarq can create liens on its property without equally and ratably securing its senior notes so long as the sum of all indebtedness so secured does not exceed 15% of Embarq's consolidated net tangible assets. The indenture also contains restrictions on the consummation of certain transactions substantially similar to CenturyLink, Inc.’s above-described covenants (but without mandatory repurchase provision), as well as certain customary covenants to maintain properties and pay all taxes and lawful claims. Impact of Covenants The debt covenants applicable to CenturyLink, Inc. and its subsidiaries could materially adversely affect their ability to operate or expand their respective businesses, to pursue strategic transactions, or to otherwise pursue their plans and strategies. The covenants of the Level 3 companies may significantly restrict the ability of CenturyLink, Inc. to receive cash from the Level 3 companies, to distribute cash from the Level 3 companies to other of CenturyLink, Inc.’s affiliated entities, or to enter into other transactions among CenturyLink, Inc.’s wholly-owned entities. Certain of the debt instruments of CenturyLink, Inc. and its subsidiaries contain cross payment default or cross acceleration provisions. When present, these provisions could have a wider impact on liquidity than might otherwise arise from a default or acceleration of a single debt instrument. The ability of CenturyLink, Inc. and its subsidiaries to comply with the financial covenants in their respective debt instruments could be adversely impacted by a wide variety of events, including unforeseen contingencies, many of which are beyond their control. Compliance At December 31, 2018 , CenturyLink, Inc. believes it and its subsidiaries were in compliance with the provisions and financial covenants contained in their respective material debt agreements in all material respects. Guarantees CenturyLink, Inc. does not guarantee the debt of any unaffiliated parties, but, as noted above, certain of its largest subsidiaries guarantee (i) its debt and letters of credit outstanding under its 2017 CenturyLink Credit Agreement and its $225 million revolving letter of credit facility and (ii) the outstanding term loans or senior notes issued by certain other subsidiaries. As further noted above, several of the subsidiaries guaranteeing these obligations have pledged substantially all of their assets to secure their respective guarantees. Subsequent Event On February 15, 2019, the Company entered into an aggregate $2.5 billion in floating-to-fixed interest rate swap agreements with five banks. Under the terms of the agreements, each month, CenturyLink will receive payments equivalent to the 1-month LIBOR from each of the five banks. Also, under the terms of the agreements, CenturyLink will pay to each bank a fixed-rate of 2.47926% monthly, with the first payment due April 30, 2019. The agreements are effective March 31, 2019 and mature on March 31, 2022.

Accounts Receivable

Accounts Receivable	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Accounts Receivable	Accounts Receivable The following table presents details of our accounts receivable balances: As of December 31, 2018 2017 (Dollars in millions) Trade and purchased receivables $ 2,094 2,245 Earned and unbilled receivables 425 436 Other 21 40 Total accounts receivable 2,540 2,721 Less: allowance for doubtful accounts (142 ) (164 ) Accounts receivable, less allowance $ 2,398 2,557 We are exposed to concentrations of credit risk from residential and business customers within our local service area, business customers outside of our local service area and from other telecommunications service providers. We generally do not require collateral to secure our receivable balances. We have agreements with other telecommunications service providers whereby we agree to bill and collect on their behalf for services rendered by those providers to our customers within our local service area. We purchase accounts receivable from other telecommunications service providers primarily on a recourse basis and include these amounts in our accounts receivable balance. We have not experienced any significant loss associated with these purchased receivables. The following table presents details of our allowance for doubtful accounts: Beginning Balance Additions Deductions Ending Balance (Dollars in millions) 2018 $ 164 153 (175 ) 142 2017 178 176 (190 ) 164 2016 152 192 (166 ) 178

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment Net property, plant and equipment is composed of the following: Depreciable Lives As of December 31, 2018 2017 (Dollars in millions) Land N/A $ 871 883 Fiber, conduit and other outside plant (1) 15-45 years 23,936 22,798 Central office and other network electronics (2) 3-10 years 18,736 18,538 Support assets (3) 3-30 years 8,020 7,586 Construction in progress (4) N/A 1,704 1,399 Gross property, plant and equipment 53,267 51,204 Accumulated depreciation (26,859 ) (24,352 ) Net property, plant and equipment $ 26,408 26,852 _______________________________________________________________________________ (1) Fiber, conduit and other outside plant consists of fiber and metallic cable, conduit, poles and other supporting structures. (2) Central office and other network electronics consists of circuit and packet switches, routers, transmission electronics and electronics providing service to customers. (3) Support assets consist of buildings, cable landing stations, data centers, computers and other administrative and support equipment. (4) Construction in progress includes inventory held for construction and property of the aforementioned categories that has not been placed in service as it is still under construction. We recorded depreciation expense of $3.3 billion , $2.7 billion and $2.7 billion for the years ended December 31, 2018 , 2017 and 2016 , respectively. Asset Retirement Obligations At December 31, 2018 , our asset retirement obligations balance was primarily related to estimated future costs of removing equipment from leased properties and estimated future costs of properly disposing of asbestos and other hazardous materials upon remodeling or demolishing buildings. Asset retirement obligations are included in other long-term liabilities on our consolidated balance sheets. As of the Level 3 acquisition date, we recorded liabilities to reflect our fair values of Level 3's asset retirement obligations. Our fair value estimates were determined using discounted cash flow method. The following table provides asset retirement obligation activity: Years Ended December 31, 2018 2017 2016 (Dollars in millions) Balance at beginning of year $ 115 95 91 Accretion expense 10 6 6 Liabilities assumed in acquisition of Level 3 (1) 58 45 — Liabilities settled (14 ) (3 ) (2 ) Liabilities transferred to Cyxtera — (20 ) — Change in estimate 21 (8 ) — Balance at end of year $ 190 115 95 (1) The liabilities assumed during 2018 relate to purchase price adjustments during the year. During 2018, we revised our estimates for the cost of removal of network equipment, tanks, and asbestos remediation resulting in a $21 million change in estimate of our asset retirement obligation. The 2018 and 2017 change in estimates are offset to gross property, plant and equipment.

Severance and Leased Real Estat

Severance and Leased Real Estate	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Severance and Leased Real Estate	Severance and Leased Real Estate Periodically, we reduce our workforce and accrue liabilities for the related severance costs. These workforce reductions result primarily from the progression or completion of our post-acquisition integration plans, increased competitive pressures, cost reduction initiatives, process improvements through automation and reduced workload demands due to the loss of customers purchasing certain services. We report severance liabilities within accrued expenses and other liabilities - salaries and benefits in our consolidated balance sheets and report severance expenses in selling, general and administrative expenses in our consolidated statements of operations. As described in Note 15—Segment Information , we do not allocate these severance expenses to our segments. We have recognized liabilities to reflect our estimates of the fair values of the existing lease obligations for real estate which we have ceased using, net of estimated sublease rentals. As of the Level 3 acquisition date, we recorded liabilities to reflect the fair values of the existing lease obligations for real estate for which we had ceased using, net of estimated sublease rentals. Our fair value estimates were determined using discounted cash flow methods. We recognize expense to reflect accretion of the discounted liabilities and periodically we adjust the expense when our actual subleasing experience differs from our initial estimates. We report the current portion of liabilities for ceased-use real estate leases in accrued expenses and other liabilities-other and report the noncurrent portion in deferred credits and other liabilities-other in our consolidated balance sheets. We report the related expenses in selling, general and administrative expenses in our consolidated statements of operations. At December 31, 2018 , the current and noncurrent portions of our leased real estate accrual were $24 million and $86 million , respectively. The remaining lease terms range from less than one year to 12.0 years, with a weighted average of 6.7 years. Changes in our accrued liabilities for severance expenses and leased real estate were as follows: Severance Real Estate (Dollars in millions) Balance at December 31, 2016 $ 98 67 Accrued to expense 42 4 Liabilities assumed in acquisition of Level 3 1 4 Payments, net (108 ) (13 ) Reversals and adjustments — 2 Balance at December 31, 2017 33 64 Accrued to expense 205 70 Payments, net (151 ) (24 ) Balance at December 31, 2018 $ 87 110

Employee Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Employee Benefits	Employee Benefits Pension, Post-Retirement and Other Post-Employment Benefits We sponsor various defined benefit pension plans (qualified and non-qualified) which, in the aggregate, cover a substantial portion of our employees including legacy CenturyLink, legacy Qwest Communications International Inc. ("Qwest") and legacy Embarq employees. Pension benefits for participants of the CenturyLink Combined Pension Plan ("Combined Pension Plan") who are represented by a collective bargaining agreement are based on negotiated schedules. All other participants' pension benefits are based on each individual participant's years of service and compensation. We also maintain non-qualified pension plans for certain current and former highly compensated employees. We maintain post-retirement benefit plans that provide health care and life insurance benefits for certain eligible retirees. We also provide other post-employment benefits for certain eligible former employees. We use a December 31 measurement date for all our plans. Pension Benefits In connection with the acquisition of Level 3 Communications, Inc. on November 1, 2017, we assumed defined benefit pension plans sponsored by various Level 3 companies for their employees. Based on a valuation analysis, we recognized a $20 million liability on November 1, 2017 for the unfunded status of the Level 3 pension plans. The net unfunded status recognized on our balance sheets at December 31, 2018 and 2017 was $11 million and $20 million , respectively, representing liabilities of $144 million and $167 million , and assets of $133 million and $147 million , respectively. Due to the insignificant impact of these pension plans on our consolidated financial statements, we have predominantly excluded them from the remaining employee benefit disclosures in this Note. United States funding laws require a company with a pension shortfall to fund the annual cost of benefits earned in addition to a seven -year amortization of the shortfall. Our funding policy for our Combined Pension Plan is to make contributions with the objective of accumulating ample assets to pay all qualified pension benefits when due under the terms of the plan. The accounting unfunded status of our qualified pension plan was $1.6 billion and $2.0 billion as of December 31, 2018 and 2017 , respectively. We made a voluntary cash contribution to our qualified pension plan of $500 million and $100 million in 2018 and 2017 , respectively, and paid $5 million of benefits directly to participants of our non-qualified pension plans in both 2018 and 2017 , respectively. Based on current laws and circumstances, we are not required to make any contributions to our qualified pension plan in 2019 . We currently do not expect to make a voluntary contribution to the trust for our qualified pension plan in 2019. We estimate that in 2019 we will pay $5 million of benefits directly to participants of our non-qualified pension plans. As previously mentioned, we sponsor unfunded non-qualified pension plans for certain current and former highly-compensated employees. The net unfunded status of our non-qualified pension plans was $52 million and $58 million for the years ended December 31, 2018 and 2017 , respectively. Due to the insignificant impact of these pension plans on our consolidated financial statements, we have predominantly excluded them from the remaining employee benefit disclosures in this Note. Post-Retirement Benefits In connection with our acquisition of Level 3 Communications, Inc. on November 1, 2017, we assumed post-retirement benefit plans sponsored by Level 3 Communications, L.L.C. and Continental Level 3, Inc. for certain of its current and former employees. Based on a valuation analysis, we recognized less than $1 million in liability for the unfunded status of Level 3’s post-retirement benefit plans. Though largely unfunded, these post-retirement plans, in the aggregate, are immaterial to our consolidated financial statements. Due to the insignificant amount of these post-retirement plans, we have predominantly excluded them from the remaining employee benefit disclosures in this Note. Our post-retirement benefit plans provide post-retirement benefits to qualified retirees and allow (i) eligible employees retiring before certain dates to receive benefits at no or reduced cost and (ii) eligible employees retiring after certain dates to receive benefits on a shared cost basis. The post-retirement benefits not paid by the trusts are funded by us and we expect to continue funding these post-retirement obligations as benefits are paid. The accounting unfunded status of our qualified post-retirement benefit plan was $3.0 billion and $3.4 billion as of December 31, 2018 and 2017 , respectively. Assets in the post-retirement trusts were substantially depleted as of December 31, 2016; however, we continue to pay certain post-retirement benefits through the trusts. No contributions were made to the post-retirement trusts in 2018 and 2017 . Benefits not paid from the trusts are expected to be paid directly by us with available cash. In 2018 , we paid $249 million of post-retirement benefits, net of participant contributions and direct subsidies. In 2019 , we expect to pay $270 million of post-retirement benefits, net of participant contributions and direct subsidies. The increase in anticipated post-retirement benefit payments is the result of increased utilization coupled with a continued rise in the cost of care. We expect our health care cost trend rate to range from 5.0% to 7.0% in 2019, 5.0% to 6.5% in 2020 and grading to 4.50% by 2025. Our post-retirement benefit cost, for certain eligible legacy Qwest retirees and certain eligible legacy CenturyLink retirees, is capped at a set dollar amount. Therefore, those health care benefit obligations are not subject to increasing health care trends after the effective date of the caps. Expected Cash Flows The Combined Pension Plan payments, post-retirement health care benefit payments and premiums, and life insurance premium payments are either distributed from plan assets or paid by us. The estimated benefit payments provided below are based on actuarial assumptions using the demographics of the employee and retiree populations and have been reduced by estimated participant contributions. Combined Pension Plan Post-Retirement Benefit Plans Medicare Part D Subsidy Receipts (Dollars in millions) Estimated future benefit payments: 2019 $ 966 277 (7 ) 2020 938 269 (7 ) 2021 916 261 (7 ) 2022 891 252 (7 ) 2023 867 243 (6 ) 2024 - 2028 3,971 1,065 (26 ) Net Periodic Benefit Expense We utilize a full yield curve approach in connection with estimating the service and interest components of net periodic benefit expense by applying the specific spot rates along the yield curve used in the determination of the benefit obligation to the relevant projected cash flow. The actuarial assumptions used to compute the net periodic benefit expense for our Combined Pension Plan and post-retirement benefit plans are based upon information available as of the beginning of the year, as presented in the following table. Combined Pension Plan Post-Retirement Benefit Plans 2018 2017 2016 2018 2017 2016 Actuarial assumptions at beginning of year: Discount rate 3.14% - 3.69% 3.25% - 4.14% 3.34% - 4.46% 4.26 % 3.90 % 4.15 % Rate of compensation increase 3.25 % 3.25 % 3.25 % N/A N/A N/A Expected long-term rate of return on plan assets (1) 6.50 % 6.50 % 7.00 % 4.00 % 5.00 % 7.00 % Initial health care cost trend rate N/A N/A N/A 7.00% / 5.00% 7.00% / 5.00% 5.00% / 5.25% Ultimate health care cost trend rate N/A N/A N/A 4.50 % 4.50 % 4.50 % Year ultimate trend rate is reached N/A N/A N/A 2025 2025 2025 _______________________________________________________________________________ N/A - Not applicable (1) Rates are presented net of projected fees and administrative costs. Net periodic benefit (income) expense for our combined pension plan includes the following components: Combined Pension Plan Years Ended December 31, 2018 2017 2016 (Dollars in millions) Service cost $ 66 63 64 Interest cost 392 409 425 Expected return on plan assets (685 ) (666 ) (733 ) Special termination benefits charge 15 — 13 Recognition of prior service credit (8 ) (8 ) (8 ) Recognition of actuarial loss 178 204 174 Net periodic pension benefit (income) expense $ (42 ) 2 (65 ) Net periodic benefit expense for our post-retirement benefit plans includes the following components: Post-Retirement Plans Years Ended December 31, 2018 2017 2016 (Dollars in millions) Service cost $ 18 18 19 Interest cost 97 100 111 Expected return on plan assets (1 ) (2 ) (7 ) Special termination benefits charge — — 3 Recognition of prior service cost 20 20 20 Net periodic post-retirement benefit expense $ 134 136 146 We report service costs for our Combined Pension Plan and post-retirement benefit plans in cost of services and products and selling, general and administrative expenses in our consolidated statements of operations for the years ended December 31, 2018 , 2017 and 2016 . Additionally, a portion of the service cost is also allocated to certain assets under construction, which are capitalized and reflected as part of property, plant and equipment in our consolidated balance sheets. The remaining components of net periodic benefit expense (income) are reported in other income, net in our consolidated statements of operations. As a result of ongoing efforts to reduce our workforce, we recognized a one-time charge in 2018 of $15 million for special termination benefit enhancements paid to certain eligible employees upon voluntary retirement. Benefit Obligations The actuarial assumptions used to compute the funded status for the plans are based upon information available as of December 31, 2018 and 2017 and are as follows: Combined Pension Plan Post-Retirement Benefit Plans December 31, December 31, 2018 2017 2018 2017 Actuarial assumptions at end of year: Discount rate 4.29 % 3.57 % 4.26 % 3.53 % Rate of compensation increase 3.25 % 3.25 % N/A N/A Initial health care cost trend rate N/A N/A 7.00% / 5.00% 7.00% / 5.00% Ultimate health care cost trend rate N/A N/A 4.50 % 4.50 % Year ultimate trend rate is reached N/A N/A 2025 2025 _______________________________________________________________________________ N/A - Not applicable In 2018, 2017 and 2016, we adopted the revised mortality tables and projection scales released by the Society of Actuaries, which decreased the projected benefit obligation of our benefit plans by $38 million , $113 million and $268 million , respectively. The change in the projected benefit obligation of our benefit plans was recognized as part of the net actuarial (gain) loss and is included in accumulated other comprehensive loss, a portion of which is subject to amortization over the remaining estimated life of plan participants, which was approximately 8 to 9 years as of December 31, 2018. The following tables summarize the change in the benefit obligations for the Combined Pension Plan and post-retirement benefit plans: Combined Pension Plan Years Ended December 31, 2018 2017 2016 (Dollars in millions) Change in benefit obligation Benefit obligation at beginning of year $ 13,064 13,244 13,287 Service cost 66 63 64 Interest cost 392 409 425 Plan amendments — — 2 Special termination benefits charge 15 — 13 Actuarial (gain) loss (765 ) 586 487 Benefits paid by company — — — Benefits paid from plan assets (1,178 ) (1,238 ) (1,034 ) Benefit obligation at end of year $ 11,594 13,064 13,244 Post-Retirement Benefit Plans Years Ended December 31, 2018 2017 2016 (Dollars in millions) Change in benefit obligation Benefit obligation at beginning of year $ 3,375 3,413 3,567 Service cost 18 18 19 Interest cost 97 100 111 Participant contributions 54 54 57 Direct subsidy receipts 8 7 5 Special termination benefits charge — — 3 Plan Amendment (36 ) — — Actuarial (gain) loss (224 ) 112 (13 ) Benefits paid by company (311 ) (298 ) (191 ) Benefits paid from plan assets (4 ) (31 ) (145 ) Benefit obligation at end of year $ 2,977 3,375 3,413 Our aggregate benefit obligation as of December 31, 2018 , 2017 and 2016 was $14.8 billion , $16.5 billion and $16.7 billion , respectively. Plan Assets We maintain plan assets for our Combined Pension Plan and certain post-retirement benefit plans. The following tables summarize the change in the fair value of plan assets for the Combined Pension Plan and post-retirement benefit plans: Combined Pension Plan Years Ended December 31, 2018 2017 2016 (Dollars in millions) Change in plan assets Fair value of plan assets at beginning of year $ 11,060 10,892 11,072 Return on plan assets (349 ) 1,306 754 Employer contributions 500 100 100 Benefits paid from plan assets (1,178 ) (1,238 ) (1,034 ) Fair value of plan assets at end of year $ 10,033 11,060 10,892 Post-Retirement Benefit Plans Years Ended December 31, 2018 2017 2016 (Dollars in millions) Change in plan assets Fair value of plan assets at beginning of year $ 23 53 193 Return on plan assets (1 ) 1 5 Benefits paid from plan assets (4 ) (31 ) (145 ) Fair value of plan assets at end of year $ 18 23 53 The expected rate of return on plan assets is the long-term rate of return we expect to earn on the plans' assets, net of administrative expenses paid from plan assets. It is determined annually based on the strategic asset allocation and the long-term risk and return forecast for each asset class. Combined Pension Plan: Our investment objective for the qualified pension plan assets is to achieve an attractive risk-adjusted return over time that will provide for the payment of benefits and minimize the risk of large losses. We employ a liability-aware investment strategy designed to reduce the volatility of pension assets relative to pension liabilities. This strategy is evaluated frequently and is expected to evolve over time with changes in the funded status and other factors. Approximately 31% of plan assets is targeted to long-duration investment grade bonds and interest rate sensitive derivatives and 29% is targeted to assets expected to outperform the liability with moderate funded status risk. Approximately 26% is targeted to public equities and 14% is targeted to private market investments. At the beginning of 2019, our expected annual long-term rate of return on pension assets before consideration of administrative expenses is assumed to be 7.0% . Projected PBGC (Pension Benefit Guaranty Corporation) premium rates reduce the annual long-term expected return net of administrative expenses to 6.5% . The short term and long term interest crediting rates during 2018 for cash balance components of the Combined Pension Plan 2018 were 3.25% and 4.00% , respectively. Post-Retirement Benefit Plans: Our investment objective for the post-retirement benefit plans' assets is to achieve an attractive risk-adjusted return and minimize the risk of large losses over the expected life of the assets. At the beginning of 2019 , our expected annual long-term rate of return on post-retirement benefit plan assets is assumed to be 4.0% . Permitted investments: Plan assets are managed consistent with the restrictions set forth by the Employee Retirement Income Security Act of 1974, as amended. Derivative instruments: Derivative instruments are used to reduce risk as well as provide return. The gross notional exposure of the derivative instruments directly held by the pension benefit plan is shown below. The notional amount of the derivatives corresponds to market exposure but does not represent an actual cash investment. Our post-retirement plans were not invested in derivative instruments for the years ended December 31, 2018 or 2017 . Gross Notional Exposure Combined Pension Plan Years Ended December 31, 2018 2017 (Dollars in millions) Derivative instruments: Exchange-traded U.S. equity futures $ 300 256 Exchange-traded Treasury and other interest rate futures 3,901 1,830 Interest rate swaps 83 137 Credit default swaps 66 100 Equity index swaps — 1 Foreign exchange forwards 295 293 Options 192 259 Fair Value Measurements: Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between independent and knowledgeable parties who are willing and able to transact for an asset or liability at the measurement date. We use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs when determining fair value and then we rank the estimated values based on the reliability of the inputs used following the fair value hierarchy set forth by the FASB. For additional information on the fair value hierarchy, see Note 13—Fair Value of Financial Instruments . At December 31, 2018 , we used the following valuation techniques to measure fair value for assets. There were no changes to these methodologies during 2018 : • Level 1—Assets were valued using the closing price reported in the active market in which the individual security was traded. • Level 2—Assets were valued using quoted prices in markets that are not active, broker dealer quotations, net asset value of shares held by the plans and other methods by which all significant inputs were observable at the measurement date. • Level 3—Assets were valued using unobservable inputs in which little or no market data exists as reported by the respective institutions at the measurement date. The tables below present the fair value of plan assets by category and the input levels used to determine those fair values at December 31, 2018 . It is important to note that the asset allocations do not include market exposures that are gained with derivatives. Investments include dividend and interest receivables, pending trades and accrued expenses. Fair Value of Combined Pension Plan Assets at December 31, 2018 Level 1 Level 2 Level 3 Total (Dollars in millions) Investment grade bonds (a) $ 458 1,393 — $ 1,851 High yield bonds (b) — 277 7 284 Emerging market bonds (c) 151 181 — 332 U.S. stocks (e) 764 2 2 768 Non-U.S. stocks (f) 601 — — 601 Private debt (i) — — 15 15 Multi-asset strategies (l) 342 — — 342 Derivatives (m) 7 (2 ) — 5 Cash equivalents and short-term investments (n) 3 907 — 910 Total investments, excluding investments valued at NAV $ 2,326 2,758 24 5,108 Investments valued at NAV 4,925 Total pension plan assets $ 10,033 Fair Value of Post-Retirement Plan Assets at December 31, 2018 Level 1 Level 2 Level 3 Total (Dollars in millions) Total investments, excluding investments valued at NAV $ — — — — Investments valued at NAV 18 Total post-retirement plan assets $ 18 The tables below present the fair value of plan assets by category and the input levels used to determine those fair values at December 31, 2017 . It is important to note that the asset allocations do not include market exposures that are gained with derivatives. Investments include dividend and interest receivable, pending trades and accrued expenses. Fair Value of Combined Pension Plan Assets at December 31, 2017 Level 1 Level 2 Level 3 Total (Dollars in millions) Investment grade bonds (a) $ 432 1,315 — $ 1,747 High yield bonds (b) — 575 7 582 Emerging market bonds (c) 217 219 1 437 U.S. stocks (e) 1,030 2 3 1,035 Non-U.S. stocks (f) 706 — — 706 Private debt (i) — — 15 15 Multi-asset strategies (l) 440 — — 440 Derivatives (m) 2 — — 2 Cash equivalents and short-term investments (n) — 476 1 477 Total investments, excluding investments valued at NAV $ 2,827 2,587 27 5,441 Investments valued at NAV 5,619 Total pension plan assets $ 11,060 Fair Value of Post-Retirement Plan Assets Level 1 Level 2 Level 3 Total (Dollars in millions) U.S. stocks (e) 1 — — 1 Total investments, excluding investments valued at NAV $ 1 — — 1 Investments valued at NAV 22 Total post-retirement plan assets $ 23 The table below presents the fair value of plan assets valued at NAV by category for our pension and post-retirement plans at December 31, 2018 and 2017 . Fair Value of Plan Assets Valued at NAV Combined Pension Plan at December 31, Post-Retirement Benefit Plans at December 31, 2018 2017 2018 2017 (Dollars in millions) Investment grade bonds (a) $ 109 163 — — High yield bonds (b) 388 483 — — Emerging market bonds (c) — 14 — — Diversified strategies (d) — 538 — — U.S. stocks (e) 150 73 — — Non-U.S. stocks (f) 500 627 — — Emerging market stocks (g) 75 98 — — Private equity (h) 347 460 6 10 Private debt (i) 452 374 1 1 Market neutral hedge funds (j) 746 769 — — Directional hedge funds (j) 512 636 — — Real estate (k) 821 903 — 1 Multi-asset strategies (l) 763 424 — — Cash equivalents and short-term investments (n) 62 57 11 10 Total investments valued at NAV $ 4,925 5,619 18 22 The plans' assets are invested in various asset categories utilizing multiple strategies and investment managers. Interests in commingled funds are valued using the net asset value ("NAV") per unit of each fund. The NAV reported by the fund manager is based on the market value of the underlying investments owned by each fund, minus its liabilities, divided by the number of shares outstanding. Commingled funds can be redeemed at NAV, generally within a year of the financial statement date. Investments in private funds, primarily limited partnerships, represent long-term commitments with a fixed maturity date and are also valued at NAV. The plan has unfunded commitments related to certain private fund investments, which in aggregate are not material to the plan. Valuation inputs for these private fund interests are generally based on assumptions and other information not observable in the market. The assumptions and valuation methodologies of the pricing vendors, account managers, fund managers and partnerships are monitored and evaluated for reasonableness. Below is an overview of the asset categories, the underlying strategies and valuation inputs used to value the assets in the preceding tables: (a) Investment grade bonds represent investments in fixed income securities as well as commingled bond funds comprised of U.S. Treasury securities, agencies, corporate bonds, mortgage-backed securities, asset-backed securities and commercial mortgage-backed securities. Treasury securities are valued at the bid price reported in the active market in which the security is traded and are classified as Level 1. The valuation inputs of other investment grade bonds primarily utilize observable market information and are based on a spread to U.S. Treasury securities and consider yields available on comparable securities of issuers with similar credit ratings. The primary observable inputs include references to the new issue market for similar securities, the secondary trading markets and dealer quotes. Option adjusted spread models are utilized to evaluate securities such as asset backed securities that have early redemption features. These securities are classified as Level 2. (b) High yield bonds represent investments in below investment grade fixed income securities as well as commingled high yield bond funds. The valuation inputs for the securities primarily utilize observable market information and are based on a spread to U.S. Treasury securities and consider yields available on comparable securities of issuers with similar credit ratings. These securities are primarily classified as Level 2. Securities whose valuation inputs are not based on observable market information are classified as Level 3. (c) Emerging market bonds represent investments in securities issued by governments and other entities located in developing countries as well as registered mutual funds and commingled emerging market bond funds. The valuation inputs for the securities utilize observable market information and are primarily based on dealer quotes or a spread relative to the local government bonds. The registered mutual fund is classified as Level 1 while individual securities are primarily classified as Level 2. Securities whose valuation inputs are not based on observable market information are classified as Level 3. (d) Diversified strategies represent an investment in a commingled fund that primarily has exposures to global government, corporate and inflation linked bonds, global stocks and commodities. This asset category includes investments in a registered mutual fund which is classified at Level 1. The valuation inputs utilize observable market information including published prices for exchange traded securities, bid prices for government bonds, and spreads and yields available for comparable fixed income securities with similar credit ratings. (e) U.S. stocks represent investments in stocks of U.S. based companies as well as commingled U.S. stock funds. The valuation inputs for U.S. stocks are based on the last published price reported on the major stock market on which the securities are traded and are primarily classified as Level 1. Securities whose valuation inputs are not based on observable market information are classified as Level 3. (f) Non-U.S. stocks represent investments in stocks of companies based in developed countries outside the U.S. as well as commingled funds. The valuation inputs for non-U.S. stocks are based on the last published price reported on the major stock market on which the securities are traded and are primarily classified as Level 1. (g) Emerging market stocks represent investments in commingled funds comprised of stocks of companies located in developing markets. The commingled funds are valued at NAV based on the market value of the underlying investments using the same valuation inputs described previously for individual stocks. (h) Private equity represents non-public investments in domestic and foreign buy out and venture capital funds. Private equity funds are primarily structured as limited partnerships and are valued according to the valuation policy of each partnership, subject to prevailing accounting and other regulatory guidelines. The partnerships are valued at NAV using valuation methodologies that consider a range of factors, including but not limited to the price at which investments were acquired, the nature of the investments, market conditions, trading values on comparable public securities, current and projected operating performance, and financing transactions subsequent to the acquisition of the investments. These valuation methodologies involve a significant degree of judgment. (i) Private debt represents non-public investments in distressed or mezzanine debt funds and pension group insurance contracts. Pension group insurance contracts are valued based on actuarial assumptions, and are classified as Level 3. Mezzanine debt instruments are debt instruments that are subordinated to other debt issues and may include embedded equity instruments such as warrants. Private debt funds are primarily structured as limited partnerships and are valued at NAV according to the valuation policy of each partnership, subject to prevailing accounting and other regulatory guidelines. The valuation of underlying fund investments are based on factors including the issuer's current and projected credit worthiness, the security's terms, reference to the securities of comparable companies, and other market factors. These valuation methodologies involve a significant degree of judgment. (j) Market neutral hedge funds hold investments in a diversified mix of instruments that are intended in combination to exhibit low correlations to market fluctuations. These investments are typically combined with futures to achieve uncorrelated excess returns over various markets. Directional hedge funds —This asset category represents investments that may exhibit somewhat higher correlations to market fluctuations than the market neutral hedge funds. Investments in hedge funds include both direct investments and investments in diversified funds of funds. Hedge funds are valued at NAV based on the market value of the underlying investments which include publicly traded equity and fixed income securities and privately negotiated debt securities. The hedge funds are valued by third party administrators using the same valuation inputs previously described. (k) Real estate represents investments in commingled funds and limited partnerships that invest in a diversified portfolio of real estate properties. These investments are valued at NAV according to the valuation policy of each fund or partnership, subject to prevailing accounting and other regulatory guidelines. The valuation inputs of the underlying properties are generally based on third-party appraisals that use comparable sales or a projection of future cash flows to determine fair value. (l) Multi-asset strategies represent broadly diversified strategies that have the flexibility to tactically adjust exposures to different asset classes through time. This asset category includes investments in a registered mutual fund which is classified as Level 1 and a commingled fund which is valued at NAV based on the market value of the underlying investments. (m) Derivatives include exchange traded futures contracts which are classified as Level 1, as well as privately negotiated over the counter swaps and options that are valued based on the change in interest rates or a specific market index and are classified as Level 2. The market values represent gains or losses that occur due to fluctuations in interest rates, foreign currency exchange rates, security prices, or other factors. (n) Cash equivalents and short-term investments represent investments that are used in conjunction with derivatives positions or are used to provide liquidity for the payment of benefits or other purposes. The valuation inputs of securities are based on a spread to U.S. Treasury Bills, the Federal Funds Rate, or London Interbank Offered Rate and consider yields available on comparable securities of issuers with similar credit ratings and are primarily classified as Level 2. The commingled funds are valued at NAV based on the market value of the underlying investments using the same valuation inputs described above. Concentrations of Risk: Investments, in general, are exposed to various risks, such as significant world events, interest rate, credit, foreign currency and overall market volatility risk. These risks are managed by broadly diversifying assets across numerous asset classes and strategies with differing expected returns, volatilities and correlations. Risk is also broadly diversified across numerous market sectors and individual companies. Financial instruments that potentially subject the plans to concentrations of counterparty risk consist principally of investment contracts with high quality financial institutions. These investment contracts are typically collateralized obligations and/or are actively managed, limiting the amount of counterparty exposure to any one financial institution. Although the investments are well diversified, the value of plan assets could change materially depending upon the overall market volatility, which could affect the funded status of the plans. The table below presents a rollforward of the pension plan assets valued using Level 3 inputs: Combined Pension Plan Assets Valued Using Level 3 Inputs High Yield Bonds Emerging Market Bonds U.S. Stocks Private Debt Cash Total (Dollars in millions) Balance at December 31, 2016 $ 11 — — — — 11 Net transfers (1 ) — — 14 — 13 Acquisitions 2 1 — 1 1 5 Dispositions (5 ) — 3 — — (2 ) Balance at December 31, 2017 7 1 3 15 1 27 Dispositions — — (2 ) — (1 ) (3 ) Actual return on plan assets — (1 ) 1 — — — Balance at December 31, 2018 $ 7 — 2 15 — 24 Certain gains and losses are allocated between assets sold during the year and assets still held at year-end based on transactions and changes in valuations that occurred during the year. These allocations also impact our calculation of net acquisitions and dispositions. For the year ended December 31, 2018 , the investment program produced actual losses on qualified pension and post-retirement plan assets of $350 million as compared to expected returns of $686 million for a difference of $1.0 billion . For the year ended December 31, 2017 , the investment program produced actual gains on qualified pension and post-retirement plan assets of $1.3 billion as compared to the expected returns of $668 million for a difference of $639 million . The short-term annual returns on plan assets will almost always be different from the expected long-term returns and the plans could experience net gains or losses, due primarily to the volatility occurring in the financial markets during any given yea

Share-based Compensation

Share-based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based Compensation	Share-based Compensation We maintain an equity incentive program that allows our Board of Directors (through its Compensation Committee or our Chief Executive Officer as its delegate) to grant incentives to certain employees and outside directors in one or more forms, including: incentive and non-qualified stock options, stock appreciation rights, restricted stock awards, restricted stock units and market and performance shares. Stock options generally expire ten years from the date of grant. Acquisition of Level 3 Upon the November 1, 2017 acquisition of Level 3, and pursuant to the terms of the merger agreement, we assumed certain of Level 3's share-based compensation awards, which were converted to settle in shares of CenturyLink common stock. Specifically: • each outstanding Level 3 restricted stock unit award granted prior to April 1, 2014 or granted to an outside director of Level 3 was converted into $26.50 in cash and 1.4286 shares of our common stock (and cash in lieu of fractional shares) with respect to each Level 3 share covered by such award (the "Converted RSU Awards"); and • each outstanding Level 3 restricted stock unit award granted on or after April 1, 2014 (other than these granted to outside directors of Level 3) was converted into a CenturyLink restricted stock unit award using a conversion ratio of 2.8386 to 1 as determined in accordance with a formula set forth in the merger agreement (the "Continuing RSU Awards"). The aggregate fair value of the replaced Level 3 awards was $239 million , of which $103 million was attributable to service performed prior to the acquisition date and was included in the cost of the acquisition. The fair value of CenturyLink shares was determined based on the $18.99 closing price of our common stock on November 1, 2017. The remaining $137 million of the preliminary aggregate fair value of the replaced Level 3 awards was attributable to post-acquisition period and is being recognized as compensation expense, net of estimated forfeitures, over the remaining 1 to 2 year vesting period. Stock Options The following table summarizes activity involving stock option awards for the year ended December 31, 2018 : Number of Options Weighted- Average Exercise Price (in thousands) Outstanding and Exercisable at December 31, 2017 1,022 $ 27.41 Exercised (178 ) 22.49 Forfeited/Expired (301 ) 30.25 Outstanding and Exercisable at December 31, 2018 543 27.46 The aggregate intrinsic value of our options outstanding and exercisable at December 31, 2018 was less than $1 million . The weighted-average remaining contractual term for such options was 1.12 years . During 2018 , we received net cash proceeds of $4 million in connection with our option exercises. The tax benefit realized from these exercises was less than $1 million . The total intrinsic value of options exercised for the years ended December 31, 2018 , 2017 and 2016 , was less than $1 million each year. Restricted Stock Awards and Restricted Stock Unit Awards For equity based restricted stock and restricted stock unit awards that contain only service conditions for vesting (time-based awards), we calculate the award fair value based on the closing price of CenturyLink common stock on the accounting grant date. We also grant equity-based awards that contain service conditions as well as additional market or performance conditions. For awards having both service and market conditions, the award fair value is calculated using Monte-Carlo simulations. Awards with service as well as market or performance conditions specify a target number of shares for the award, although each recipient ultimately has the opportunity to receive between 0% and 200% of the target number of shares. For awards with service and market conditions, the percentage received is based on our total shareholder return over the three -year service period versus that of selected peer companies. For awards with service and performance conditions, the percentage received depends upon the attainment of two financial performance targets during the three -year service period. The following table summarizes activity involving restricted stock and restricted stock unit awards for the year ended December 31, 2018 : Number of Shares Weighted- Average Grant Date Fair Value (in thousands) Non-vested at December 31, 2017 19,774 $ 21.90 Granted (1) 9,657 17.02 Vested (9,275 ) 20.87 Forfeited (3,097 ) 22.12 Non-vested at December 31, 2018 17,059 19.65 _____________________________________________________________________________ (1) Shares granted whose related performance conditions were not finalized at December 31, 2018, were excluded from this figure. During 2017 , we granted 5.2 million shares of restricted stock and restricted stock unit awards at a weighted-average price of $22.02 . During 2016, we granted 3.6 million shares of restricted stock and restricted stock unit awards at a weighted-average price of $30.83 . The total fair value of restricted stock that vested during 2018 , 2017 and 2016 , was $169 million , $60 million and $47 million , respectively. Compensation Expense and Tax Benefit We recognize compensation expense related to our market and performance share-based awards with graded vesting that only have a service condition on a straight-line basis over the requisite service period for the entire award. Total compensation expense for all share-based payment arrangements for the years ended December 31, 2018 , 2017 and 2016 , was $185 million , $111 million and $80 million , respectively. Our tax benefit recognized in the consolidated statements of operations for our share-based payment arrangements for the years ended December 31, 2018 , 2017 and 2016 , was $46 million , $28 million and $31 million , respectively. At December 31, 2018 , there was $215 million of total unrecognized compensation expense related to our share-based payment arrangements, which we expect to recognize over a weighted-average period of 1.7 years.

(Loss) Earnings Per Common Shar

(Loss) Earnings Per Common Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
(Loss) Earnings Per Common Share	(Loss) Earnings Per Common Share Basic and diluted (loss) earnings per common share for the years ended December 31, 2018 , 2017 and 2016 were calculated as follows: Years Ended December 31, 2018 2017 2016 (Dollars in millions, except per share amounts, shares in thousands) Loss income (Numerator): Net (loss) income $ (1,733 ) 1,389 626 Net (loss) income applicable to common stock for computing basic earnings per common share (1,733 ) 1,389 626 Net (loss) income as adjusted for purposes of computing diluted earnings per common share $ (1,733 ) 1,389 626 Shares (Denominator): Weighted average number of shares: Outstanding during period 1,078,409 635,576 545,946 Non-vested restricted stock (12,543 ) (7,768 ) (6,397 ) Weighted average shares outstanding for computing basic earnings per common share 1,065,866 627,808 539,549 Incremental common shares attributable to dilutive securities: Shares issuable under convertible securities — 10 10 Shares issuable under incentive compensation plans — 875 1,120 Number of shares as adjusted for purposes of computing diluted (loss) earnings per common share 1,065,866 628,693 540,679 Basic (loss) earnings per common share $ (1.63 ) 2.21 1.16 Diluted (loss) earnings per common share (1) $ (1.63 ) 2.21 1.16 _______________________________________________________________________________ (1) For the year ended December 31, 2018, we excluded from the calculation of diluted loss per share 4.6 million shares potentially issuable under incentive compensation plans or convertible securities, as their effect, if included, would have been anti-dilutive. Our calculation of diluted (loss) earnings per common share excludes shares of common stock that are issuable upon exercise of stock options when the exercise price is greater than the average market price of our common stock. We also exclude unvested restricted stock awards that are antidilutive as a result of unrecognized compensation cost. Such shares averaged 2.7 million , 4.7 million and 3.3 million for 2018 , 2017 and 2016 , respectively.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments Our financial instruments consist of cash, cash equivalents and restricted cash, accounts receivable, accounts payable and long-term debt, excluding capital lease and other obligations. Due to their short-term nature, the carrying amounts of our cash, cash equivalents and restricted cash, accounts receivable and accounts payable approximate their fair values. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between independent and knowledgeable parties who are willing and able to transact for an asset or liability at the measurement date. We use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs when determining fair value and then we rank the estimated values based on the reliability of the inputs used following the fair value hierarchy set forth by the FASB. We determined the fair values of our long-term debt, including the current portion, based on quoted market prices where available or, if not available, based on discounted future cash flows using current market interest rates. The three input levels in the hierarchy of fair value measurements are defined by the FASB generally as follows: Input Level Description of Input Level 1 Observable inputs such as quoted market prices in active markets. Level 2 Inputs other than quoted prices in active markets that are either directly or indirectly observable. Level 3 Unobservable inputs in which little or no market data exists. The following table presents the carrying amounts and estimated fair values of our long-term debt, excluding capital lease and other obligations, as well as the input level used to determine the fair values indicated below: As of December 31, 2018 As of December 31, 2017 Input Level Carrying Amount Fair Value Carrying Amount Fair Value (Dollars in millions) Liabilities-Long-term debt, excluding capital lease and other obligations 2 $ 35,260 32,915 36,835 36,402

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the Tax Cuts and Jobs Act (the "Act") was signed into law. The Act reduces the U.S. corporate income tax rate from a maximum of 35% to 21% for all corporations, effective January 1, 2018, and makes certain changes to U.S. taxation of income earned by foreign subsidiaries, capital expenditures, interest expense and various other items. As a result of the reduction in the U.S. corporate income tax rate from 35% to 21% , we re-measured our net deferred tax liabilities at December 31, 2017 and recognized a provisional tax benefit of approximately $1.1 billion in our consolidated statement of operations for the year ended December 31, 2017. As a result of finalizing our provisional amount recorded in 2017, we recorded a reduction to this amount for purchase price accounting adjustments resulting from the Level 3 acquisition and the tax reform impact on those adjustments of $92 million in 2018. The Act also includes certain anti-abuse and base erosion provisions that may impact the amounts of U.S. tax that we pay with respect to income earned by our foreign subsidiaries. We have completed our analysis of the impact of the one-time repatriation tax and concluded that we do not have a tax liability under this provision. We have also completed our analysis of the anti-abuse and base erosion provisions and have recorded a tax expense of $11 million related to global intangible low-taxed income provisions of the Act and do not have a liability in relation to base erosion and anti-abuse tax provisions of the Act. Years Ended December 31, 2018 2017 2016 (Dollars in millions) Income tax expense (benefit) was as follows: Federal Current $ (576 ) 82 335 Deferred 734 (988 ) 5 State Current (22 ) 21 27 Deferred 52 16 8 Foreign Current 36 22 26 Deferred (54 ) (2 ) (7 ) Total income tax expense (benefit) $ 170 (849 ) 394 Years Ended December 31, 2018 2017 2016 (Dollars in millions) Income tax (benefit) expense was allocated as follows: Income tax (benefit) expense in the consolidated statements of operations: Attributable to income $ 170 (849 ) 394 Stockholders' equity: Compensation expense for tax purposes in excess of amounts recognized for financial reporting purposes — — (2 ) Tax effect of the change in accumulated other comprehensive loss (2 ) 81 (109 ) The following is a reconciliation from the statutory federal income tax rate to our effective income tax rate: Years Ended December 31, 2018 2017 2016 (Percentage of pre-tax income) Statutory federal income tax rate 21.0 % 35.0 % 35.0 % State income taxes, net of federal income tax benefit (1.5 )% 3.9 % 2.3 % Impairment of goodwill (36.6 )% — % — % Change in liability for unrecognized tax position 1.3 % 1.0 % 0.2 % Tax reform (5.9 )% (209.8 )% — % Net foreign income taxes 1.8 % (0.7 )% 0.1 % Foreign dividend paid to a domestic parent company — % 0.2 % 1.8 % Research and development credits 0.9 % (1.4 )% (0.6 )% Tax impact on sale of data centers and colocation business — % 5.0 % — % Tax benefit of net operating loss carryback 9.1 % — % — % Level 3 acquisition transaction costs — % 6.0 % — % Other, net (1.0 )% 3.6 % (0.2 )% Effective income tax rate (10.9 )% (157.2 )% 38.6 % The effective tax rate for the year ended December 31, 2018 reflects a $572 million unfavorable impact of the non-deductible goodwill impairment and a $92 million unfavorable impact due to finalizing the impacts of tax reform. Partially offsetting these amounts is a $142 million benefit generated by a loss carryback to 2016. The effective tax rate for the year ended December 31, 2017 reflects the benefit of approximately $1.1 billion from the re-measurement of deferred taxes as noted above, a $27 million tax expense related to the sale of our colocation business and $32 million tax impact of non-deductible transaction costs related to the Level 3 acquisition. The effective tax rate for the year ended December 31, 2016 reflects a tax impact of $18 million from an intercompany dividend payment from one of our foreign subsidiaries to its domestic parent company that was made as part of our corporate restructuring in preparation for the sale of our colocation business. The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and deferred tax liabilities were as follows: As of December 31, 2018 2017 (Dollars in millions) Deferred tax assets Post-retirement and pension benefit costs $ 1,111 1,321 Net operating loss carryforwards 3,445 3,951 Other employee benefits 162 112 Other 553 714 Gross deferred tax assets 5,271 6,098 Less valuation allowance (1,331 ) (1,341 ) Net deferred tax assets 3,940 4,757 Deferred tax liabilities Property, plant and equipment, primarily due to depreciation differences (3,011 ) (2,935 ) Goodwill and other intangible assets (3,303 ) (3,785 ) Other (23 ) (16 ) Gross deferred tax liabilities (6,337 ) (6,736 ) Net deferred tax liability $ (2,397 ) (1,979 ) Of the $2.4 billion and $2.0 billion net deferred tax liability at December 31, 2018 and 2017 , respectively, $2.5 billion and $2.4 billion is reflected as a long-term liability and $131 million and $434 million is reflected as a net noncurrent deferred tax asset at December 31, 2018 and 2017 , respectively. At December 31, 2018 , we had federal NOLs of $7.3 billion , net of limitations of Section 382 of the Internal Revenue Code ("Section 382") and uncertain tax positions, for U.S. federal income tax purposes. If unused, the NOLs will expire between 2022 and 2037 . The U.S. federal net operating loss carryforwards expire as follows: Expiring Amount December 31, (Dollars in millions) 2022 $ 1,043 2023 1,440 2024 1,402 2025 1,042 2026 1,525 2027 375 2028 637 2029 645 2030 671 2031 732 2032 348 2033 238 2037 2,715 NOLs per return 12,813 Uncertain tax positions (5,526 ) Financial NOLs $ 7,287 At December 31, 2018 we had state net operating loss carryforwards of $19 billion (net of uncertain tax positions). We also had foreign NOL carryforwards of $6 billion . At December 31, 2018 , we had federal tax credits of $52 million . Our acquisitions of Level 3, Qwest and SAVVIS, Inc. caused "ownership changes" within the meaning of Section 382 for the acquired companies. As a result, our ability to use these NOLs and tax credits are subject to annual limits imposed by Section 382. Despite this, we expect to use substantially all of these tax attributes to reduce our future federal tax liabilities, although the timing of that use will depend upon our future earnings and future tax circumstances. We establish valuation allowances when necessary to reduce the deferred tax assets to amounts we expect to realize. As of December 31, 2018 , a valuation allowance of $1.3 billion was established as it is more likely than not that this amount of net operating loss, capital loss and tax credit carryforwards will not be utilized prior to expiration. Our valuation allowance at December 31, 2018 and 2017 is primarily related to foreign and state NOL carryforwards. This valuation allowance decreased by $10 million during 2018 , primarily due to the impact of foreign exchange rate adjustments and state law changes. A reconciliation of the change in our gross unrecognized tax benefits (excluding both interest and any related federal benefit) from January 1 to December 31 for 2018 and 2017 is as follows: 2018 2017 (Dollars in millions) Unrecognized tax benefits at beginning of year $ 40 16 Assumed in the acquisition of Level 3 — 18 Tax position of prior periods netted against deferred tax assets 1,338 2 Increase in tax positions taken in the current year 4 1 Increase in tax positions taken in the prior year 211 3 Decrease due to payments/settlements (1 ) — Decrease from the lapse of statute of limitations (2 ) — Decrease due to the reversal of tax positions taken in a prior year (3 ) — Unrecognized tax benefits at end of year $ 1,587 40 The total amount (including both interest and any related federal benefit) of unrecognized tax benefits that, if recognized, would impact the effective income tax rate was $256 million and $66 million at December 31, 2018 and 2017 , respectively. Our policy is to reflect interest expense associated with unrecognized tax benefits in income tax expense. We had accrued interest (presented before related tax benefits) of approximately $17 million and $56 million at December 31, 2018 and 2017 , respectively. We, or at least one of our subsidiaries, file income tax returns in the U.S. federal jurisdiction and various states and foreign jurisdictions. With few exceptions, we are no longer subject to U.S. federal, state and local, or non-U.S. income tax examinations by tax authorities for years before 2003. The Internal Revenue Service and state and local taxing authorities reserve the right to audit any period where net operating loss carryforwards are available. Based on our current assessment of various factors, including (i) the potential outcomes of these ongoing examinations, (ii) the expiration of statute of limitations for specific jurisdictions, (iii) the negotiated settlement of certain disputed issues, and (iv) the administrative practices of applicable taxing jurisdictions, it is reasonably possible that the related unrecognized tax benefits for uncertain tax positions previously taken may decrease by up to $12 million within the next 12 months. The actual amount of such decrease, if any, will depend on several future developments and events, many of which are outside our control.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information At December 31, 2018, we had the following two segments: • Business Segment. Under our business segment, we provide our products and services to large domestic and global enterprises, small and medium businesses, federal, state and local governments and wholesale customers, including other communication providers. Our products and services offered to these customers include our IP and Data Services suite of products, which includes VPN and hybrid networking, Ethernet and IP services; Transport and Infrastructure, which includes wavelengths and private line, dark fiber, colocation and data center services, and professional services; Voice Services, which includes local, long-distance, toll-free and unified communications services; and IT and Managed services, all of which are described further under "Products and Services"; and • Consumer Segment. Under our consumer segment, we provide our products and services to residential customers. Our products and services offered to these customers include our broadband, local and long-distance voice, video and other ancillary services. The following table summarizes our segment results for 2018 , 2017 and 2016 based on the segment categorization we were operating under at December 31, 2018 . Years Ended December 31, 2018 2017 2016 (Dollars in millions) Total segment revenue $ 22,720 16,924 16,766 Total segment expenses 12,269 9,390 9,081 Total segment adjusted EBITDA $ 10,451 7,534 7,685 Total margin percentage 46 % 45 % 46 % Business segment: Revenue $ 17,349 11,220 10,704 Expenses 10,076 6,847 6,391 Adjusted EBITDA $ 7,273 4,373 4,313 Margin percentage 42 % 39 % 40 % Consumer segment: Revenue $ 5,371 5,704 6,062 Expenses 2,193 2,543 2,690 Adjusted EBITDA $ 3,178 3,161 3,372 Margin percentage 59 % 55 % 56 % Product and Service Categories We categorize our products, services and revenue among the following five categories: • IP and Data Services , which include primarily VPN data networks, Ethernet, IP, video (including our facilities-based video services, CDN services and Vyvx broadcast services) and other ancillary services; • Transport and Infrastructure , which include broadband, private line (including business data services), data center facilities and services, including cloud, hosting and application management solutions, wavelength, equipment sales and professional services, network security services, dark fiber services and other ancillary services; • Voice and Collaboration , which includes primarily local and long-distance voice, including wholesale voice, and other ancillary services; • IT and Managed Services , which include information technology services and managed services, which may be purchased in conjunction with our other network services; and • Regulatory Revenue, which consist of (i) Universal Service Fund ("USF"), Connect America Fund ("CAF") and other support payments designed to reimburse us for various costs related to certain telecommunications services and (ii) other operating revenue from the leasing and subleasing of space, none of which is included in our segment revenue. Our operating revenue for our products and services are presented as follows for the years ended December 31, 2018 , 2017 and 2016 : Years Ended December 31, 2018 2017 2016 (Dollars in millions) Business segment IP and Data Services (1) $ 6,971 3,682 2,957 Transport and Infrastructure (2) 5,356 3,569 3,807 Voice and Collaboration (3) 4,401 3,317 3,299 IT and Managed Services (4) 621 652 641 Total business segment revenue 17,349 11,220 10,704 Consumer segment IP and Data Services (5) 308 401 461 Transport and Infrastructure (6) 2,892 2,776 2,776 Voice and Collaboration (3) 2,171 2,527 2,825 Total consumer segment revenue 5,371 5,704 6,062 Non-segment revenue Regulatory Revenue (7) 723 732 704 Total non-segment revenue 723 732 704 Total revenue $ 23,443 17,656 17,470 ______________________________________________________________________ (1) Includes primarily VPN data network, Ethernet, IP and ancillary revenue. (2) Includes primarily broadband, private line (including business data services), colocation and data centers, wavelength and ancillary revenue. (3) Includes local, long-distance and other ancillary revenue. (4) Includes IT services and managed services revenue. (5) Includes retail video revenue (including our facilities-based video revenue). (6) Includes primarily broadband and equipment sales and professional services revenue. (7) Includes CAF Phase I, CAF Phase II, federal and state USF support revenue, sublease rental income and failed-sale leaseback income. We recognize revenue in our consolidated statements of operations for certain USF surcharges and transaction taxes that we bill to our customers. Our consolidated statements of operations also reflect the offsetting expense for the amounts we remit to the government agencies. The total amount of such surcharges and transaction taxes that we included in revenue aggregated to $952 million , $601 million and $572 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. These USF surcharges, where we record revenue, and transaction taxes are assigned to the product and service categories of each segments based on the underlying revenue. We also act as a collection agent for certain other USF and transaction taxes that we are required by government agencies to bill our customers, for which we do not record any revenue or expense because we only act as a pass-through agent. Allocations of Revenue and Expenses Our segment revenue includes all revenue from our business and consumer segments as described in more detail above. Our segment revenue is based upon each customer's classification. We report our segment revenue based upon all services provided to that segment's customers. Our segment expenses include specific expenses incurred as a direct result of providing services and products to segment customers, along with selling, general and administrative expenses that are (i) directly associated with specific segment customers or activities, and (ii) allocated expenses which include network expenses, facilities expenses and other expenses such as fleet and real estate expenses. We do not assign depreciation and amortization expense or impairments to our segments, as the related assets and capital expenditures are centrally managed and are not monitored by or reported to the CODM by segment. Generally speaking, severance expenses, restructuring expenses and certain centrally managed administrative functions (such as finance, information technology, legal and human resources) are not assigned to our segments. Interest expense is also excluded from segment results because we manage our financing on a consolidated basis and have not allocated assets or debt to specific segments. Other income and expense items are not monitored as a part of our segment operations and are therefore excluded from our segment results. The following table reconciles total segment adjusted EBITDA to net (loss) income for the years ended December 31, 2018 , 2017 and 2016 : Years Ended December 31, 2018 2017 2016 (Dollars in millions) Total segment adjusted EBITDA $ 10,451 7,534 7,685 Regulatory Revenue 723 732 704 Depreciation and amortization (5,120 ) (3,936 ) (3,916 ) Impairment of goodwill (2,726 ) — — Other operating expenses (2,758 ) (2,321 ) (2,140 ) Total other expenses, net (2,133 ) (1,469 ) (1,313 ) Income (loss) before income tax expense (1,563 ) 540 1,020 Income tax (expense) benefit (170 ) 849 (394 ) Net (loss) income $ (1,733 ) 1,389 626 We do not have any single customer that provides more than 10% of our consolidated total operating revenue. The assets we hold outside of the U.S. represent less than 10% of our total assets. Revenue from sources outside of the U.S. is responsible for less than 10% of our total operating revenue.

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (Unaudited)	Quarterly Financial Data (Unaudited) First Quarter Second Quarter Third Quarter Fourth Quarter Total (Dollars in millions, except per share amounts) 2018 Operating revenue $ 5,945 5,902 5,818 5,778 23,443 Operating income (loss) 750 767 894 (1,841 ) 570 Net income (loss) 115 292 272 (2,412 ) (1,733 ) Basic earnings (loss) per common share 0.11 0.27 0.25 (2.26 ) (1.63 ) Diluted earnings (loss) per common share 0.11 0.27 0.25 (2.26 ) (1.63 ) 2017 Operating revenue $ 4,209 4,090 4,034 5,323 17,656 Operating income 631 367 487 524 2,009 Net income 163 17 92 1,117 1,389 Basic earnings per common share 0.30 0.03 0.17 1.26 2.21 Diluted earnings per common share 0.30 0.03 0.17 1.26 2.21 During the fourth quarter of 2018, we recorded a non-cash, non-tax-deductible goodwill impairment charge of $2.7 billion for goodwill assigned to our consumer segment. During the first quarter of 2018, we recognized $71 million of expenses related to our acquisition of Level 3 followed by acquisition-related expenses of $162 million , $43 million and $117 million in the second, third and fourth quarters of 2018, respectively. During the first quarter of 2017, we recognized $10 million of expenses related to our acquisition of Level 3 followed by acquisition-related expenses of $18 million , $37 million and $206 million in the second, third and fourth quarters of 2017, respectively. During the first quarter of 2017, depreciation and amortization expense of $50 million was not recognized on colocation assets held for sale. During the second quarter, we recognized a combined loss of $119 million resulting from the sale of the colocation business and data centers and the accounting treatment of the failed-sale-leaseback. During the second quarter of 2017, we recognized a one-time depreciation charge of $44 million related to the failed-sale-leaseback accounting. During the third and fourth quarters of 2017, we recognized $44 million and $20 million , respectively, of interest expense related to CenturyLink, Inc.'s $6 billion secured term loan utilized in the acquisition of Level 3. In the fourth quarter of 2017, we recognized a tax benefit of approximately $1.1 billion due to the change in the federal corporate tax rate from 35% to 21% .

Commitments, Contingencies and

Commitments, Contingencies and Other Items	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies and Other Items	Commitments, Contingencies and Other Items We are subject to various claims, legal proceedings and other contingent liabilities, including the matters described below, which individually or in the aggregate could materially affect our financial condition, future results of operations or cash flows. As a matter of course, we are prepared to both litigate these matters to judgment as needed, as well as to evaluate and consider reasonable settlement opportunities. Irrespective of its merits, litigation may be both lengthy and disruptive to our operations and could cause significant expenditure and diversion of management attention. We review our litigation accrual liabilities on a quarterly basis, but in accordance with applicable accounting guidelines only establish accrual liabilities when losses are deemed probable and reasonably estimable and only revise previously-established accrual liabilities when warranted by changes in circumstances, in each case based on then-available information. As such, as of any given date we could have exposure to losses under proceedings as to which no liability has been accrued or as to which the accrued liability is inadequate. Amounts accrued for our litigation and non-income tax contingencies at December 31, 2018 aggregated to approximately $123 million and are included in other current liabilities and other liabilities in our consolidated balance sheet as of such date. The establishment of an accrual does not mean that actual funds have been set aside to satisfy a given contingency. Thus, the resolution of a particular contingency for the amount accrued could have no effect on our results of operations but nonetheless could have an adverse effect on our cash flows. In this Note, when we refer to a class action as "putative" it is because a class has been alleged, but not certified in that matter. Shareholder Class Action Suits CenturyLink and certain members of the CenturyLink Board of Directors have been named as defendants in a putative shareholder class action lawsuit filed on January 11, 2017 in the 4th Judicial District Court of the State of Louisiana, Ouachita Parish, captioned Jeffery Tomasulo v. CenturyLink, Inc., et al. The complaint asserts, among other things, that the members of CenturyLink’s Board allegedly breached their fiduciary duties to the CenturyLink shareholders in approving the Level 3 merger agreement and, more particularly, that: the consideration that CenturyLink agreed to pay to Level 3 stockholders in the transaction is allegedly unfairly high; the CenturyLink directors allegedly had conflicts of interest in negotiating and approving the transaction; and the disclosures set forth in our preliminary joint proxy statement/prospectus filed in December 2016 are insufficient in that they allegedly fail to contain material information concerning the transaction. The complaint seeks, among other things, a declaration that the members of the CenturyLink Board have breached their fiduciary duties, corrective disclosure, rescissory or other damages and equitable relief, including rescission of the transaction. In February 2017, the parties entered into a memorandum of understanding providing for the settlement of the lawsuit. In January 2019, the court approved the settlement and entered final judgment. An objector filed an appeal, and that appeal is pending. The costs of the settlement are not material to our consolidated financial statements. CenturyLink and certain CenturyLink board members and officers were named as defendants in a putative shareholder class action lawsuit filed on June 12, 2018 in the Boulder County District Court of the state of Colorado, captioned Houser et al. v. CenturyLink, et al. The complaint asserts claims on behalf of a putative class of former Level 3 shareholders who became CenturyLink shareholders as a result of the transaction. It alleges that the proxy statement provided to the Level 3 shareholders failed to disclose material information of several kinds, including information about strategic revenue, customer loss rates, and customer account issues, among other items. The complaint seeks damages, costs and fees, rescission, rescissory damages, and other equitable relief. Switched Access Disputes Subsidiaries of CenturyLink, Inc. are among hundreds of companies involved in an industry-wide dispute, raised in nearly 100 federal lawsuits (filed between 2014 and 2016) that have been consolidated in the United States District Court for the Northern District of Texas for pretrial procedures. The disputes relate to switched access charges that local exchange carriers ("LECs") collect from interexchange carriers ("IXCs") for IXCs' use of LEC's access services. In the lawsuits, IXCs, including Sprint Communications Company L.P. ("Sprint") and various affiliates of Verizon Communications Inc. ("Verizon"), assert that federal and state laws bar LECs from collecting access charges when IXCs exchange certain types of calls between mobile and wireline devices that are routed through an IXC. Some of these IXCs have asserted claims seeking refunds of payments for access charges previously paid and relief from future access charges. In November 2015, the federal court agreed with the LECs and rejected the IXCs' contention that federal law prohibits these particular access charges, and also allowed the IXCs to refile state-law claims. Since then, many of the LECs and IXCs have filed revised pleadings and additional motions, which remain pending. Separately, some of the defendants, including CenturyLink, Inc.'s LECs, have petitioned the FCC to address these issues on an industry-wide basis. Our subsidiaries include both IXCs and LECs which respectively pay and assess significant amounts of the charges in question. The outcome of these disputes and lawsuits, as well as any related regulatory proceedings that could ensue, are currently not predictable. State Tax Suits Several Missouri municipalities have, beginning in May 2012, asserted claims alleging underpayment of taxes against CenturyLink, Inc. and several of its subsidiaries in a number of proceedings filed in the Circuit Court of St. Louis County, Missouri. These municipalities are seeking, among other things, declaratory relief regarding the application of business license and gross receipts taxes and back taxes from 2007 to the present, plus penalties and interest. In a February 2017 ruling in connection with one of these pending cases, the court entered an order awarding plaintiffs $4 million and broadening the tax base on a going-forward basis. We have appealed that ruling. In a June 2017 ruling in connection with another one of these pending cases, the court made findings which, if not overturned, will result in a tax liability to us well in excess of the contingent liability we have established. In due course, we plan to appeal that decision. We continue to vigorously defend against these claims. Billing Practices Suits In June 2017, a former employee filed an employment lawsuit against us claiming that she was wrongfully terminated for alleging that we charged some of our retail customers for products and services they did not authorize. Starting shortly thereafter and continuing since then, and based in part on the allegations made by the former employee, several legal proceedings have been filed. In June 2017, McLeod v. CenturyLink, a putative consumer class action, was filed against us in the U.S. District Court for the Central District of California alleging that we charged some of our retail customers for products and services they did not authorize. A number of other complaints asserting similar claims have been filed in other federal and state courts, as well. The lawsuits assert claims including fraud, unfair competition, and unjust enrichment. Also in June 2017, Craig. v. CenturyLink, Inc., et al., a putative securities investor class action, was filed in U.S. District Court for the Southern District of New York, alleging that we failed to disclose material information regarding improper sales practices, and asserting federal securities law claims. A number of other cases asserting similar claims have also been filed. Beginning June 2017, we also received several shareholder derivative demands addressing related topics. In August 2017, the Board of Directors formed a special litigation committee of outside directors to address the allegations of impropriety contained in the shareholder derivative demands. In April 2018, the special litigation committee concluded its review of the derivative demands and declined to take further action. Since then, derivative cases were filed. Two of these cases, Castagna v. Post and Pinsly v. Post, were filed in Louisiana state court in the Fourth Judicial District Court for the Parish of Ouachita. The remaining derivative cases were filed in federal court in Louisiana and Minnesota. These cases have been brought on behalf of CenturyLink against certain current and former officers and directors of the Company and seek damages for alleged breaches of fiduciary duties. The consumer putative class actions, the securities investor putative class actions, and the federal derivative actions have been transferred to the U.S. District Court for the District of Minnesota for coordinated and consolidated pretrial proceedings as In Re: CenturyLink Sales Practices and Securities Litigation. In July 2017, the Minnesota state attorney general filed State of Minnesota v. CenturyTel Broadband Services LLC, et al. in the Anoka County Minnesota District Court, alleging claims of fraud and deceptive trade practices relating to improper consumer sales practices. The suit seeks an order of restitution on behalf of all CenturyLink customers, civil penalties, injunctive relief, and costs and fees. Additionally, we have received and responded to information requests and inquiries from other states. Peruvian Tax Litigation In 2005, the Peruvian tax authorities ("SUNAT") issued tax assessments against one of our Peruvian subsidiaries asserting $26 million of additional income tax withholding and value-added taxes ("VAT"), penalties and interest for calendar years 2001 and 2002 on the basis that the Peruvian subsidiary incorrectly documented its importations. After taking into account the developments described below, as well as the accrued interest and foreign exchange effects, we believe the total amount of exposure is $11 million at December 31, 2018. We challenged the assessments via administrative and then judicial review processes. In October 2011, the highest administrative review tribunal (the "Tribunal") decided the central issue underlying the 2002 assessments in SUNAT's favor. We appealed the Tribunal's decision to the first judicial level, which decided the central issue in favor of Level 3. SUNAT and we filed cross-appeals with the court of appeal. In May 2017, the court of appeal issued a decision reversing the first judicial level. In June 2017, we filed an appeal of the decision to the Supreme Court of Justice, the final judicial level. Oral argument was held before the Supreme Court of Justice in October 2018. A decision on this case is pending. In October 2013, the Tribunal decided the central issue underlying the 2001 assessments in SUNAT’s favor. We appealed that decision to the first judicial level in Peru, which decided the central issue in favor of SUNAT. In June 2017, we filed an appeal with the court of appeal. In November 2017, the court of appeals issued a decision affirming the first judicial level and we filed an appeal of the decision to the Supreme Court of Justice. That appeal is pending. Brazilian Tax Claims In December 2004, March 2009, April 2009 and July 2014, the São Paulo state tax authorities issued tax assessments against one of our Brazilian subsidiaries for the Tax on Distribution of Goods and Services (“ICMS”) with respect to revenue from leasing certain assets (in the case of the December 2004, March 2009 and July 2014 assessments) and revenue from the provision of Internet access services (in the case of the April 2009 and July 2014 assessments), by treating such activities as the provision of communications services, to which the ICMS tax applies. In September 2002, July 2009 and May 2012, the Rio de Janeiro state tax authorities issued tax assessments to the same Brazilian subsidiary on similar issues. We have filed objections to these assessments, arguing that the lease of assets and the provision of Internet access are not communication services subject to ICMS. The objections to the September 2002, December 2004 and March 2009 assessments were rejected by the respective state administrative courts, and we have appealed those decisions to the judicial courts. In October 2012 and June 2014, we received favorable rulings from the lower court on the December 2004 and March 2009 assessments regarding equipment leasing, but those rulings are subject to appeal by the state. No ruling has been obtained with respect to the September 2002 assessment. The objections to the April and July 2009 and May 2012 assessments are still pending final administrative decisions. The July 2014 assessment was confirmed during the fourth quarter of 2014 at the first administrative level, and we appealed this decision to the second administrative level. We are vigorously contesting all such assessments in both states and, in particular, view the assessment of ICMS on revenue from equipment leasing to be without merit. These assessments, if upheld, could result in a loss of up to $37 million at December 31, 2018 in excess of the accruals established for these matters. Qui Tam Action Level 3 was notified in late 2017 of a qui tam action pending against Level 3 Communications, Inc. and others in the United States District Court for the Eastern District of Virginia, captioned United States of America ex rel., Stephen Bishop v. Level 3 Communications, Inc. et al. The original qui tam complaint was filed under seal on November 26, 2013, and an amended complaint was filed under seal on June 16, 2014. The court unsealed the complaints on October 26, 2017. The amended complaint alleges that Level 3, principally through two former employees, submitted false claims and made false statements to the government in connection with two government contracts. The relator seeks damages in this lawsuit of approximately $50 million , subject to trebling, plus statutory penalties, pre-and-post judgment interest, and attorney’s fees. The case is currently stayed. Level 3 is evaluating its defenses to the claims. At this time, Level 3 does not believe it is probable Level 3 will incur a material loss. If, contrary to its expectations, the plaintiff prevails in this matter and proves damages at or near $50 million , and is successful in having those damages trebled, the outcome could have a material adverse effect on our results of operations in the period in which a liability is recognized and on our cash flows for the period in which any damages are paid. Several people, including two former Level 3 employees were indicted in the United States District Court for the Eastern District of Virginia on October 3, 2017, and charged with, among other things, accepting kickbacks from a subcontractor, who was also indicted, for work to be performed under a prime government contract. Of the two former employees, one entered into a plea agreement, and the other is deceased. Level 3 is fully cooperating in the government’s investigations in this matter. Other Proceedings, Disputes and Contingencies From time to time, we are involved in other proceedings incidental to our business, including patent infringement allegations, administrative hearings of state public utility commissions relating primarily to our rates or services, actions relating to employee claims, various tax issues, environmental law issues, grievance hearings before labor regulatory agencies and miscellaneous third party tort actions. We are currently defending several patent infringement lawsuits asserted against us by non-practicing entities, many of which are seeking substantial recoveries. These cases have progressed to various stages and one or more may go to trial in the coming 24 months if they are not otherwise resolved. Where applicable, we are seeking full or partial indemnification from our vendors and suppliers. As with all litigation, we are vigorously defending these actions and, as a matter of course, are prepared to litigate these matters to judgment, as well as to evaluate and consider all reasonable settlement opportunities. We are subject to various foreign, federal, state and local environmental protection and health and safety laws. From time to time, we are subject to judicial and administrative proceedings brought by various governmental authorities under these laws. Several such proceedings are currently pending, but none is reasonably expected to exceed $100,000 in fines and penalties. The outcome of these other proceedings described under this heading is not predictable. However, based on current circumstances, we do not believe that the ultimate resolution of these other proceedings, after considering available defenses and any insurance coverage or indemnification rights, will have a material adverse effect on us. The ultimate outcome of the above-described matters may differ materially from the outcomes anticipated, estimated, projected or implied by us in certain of our statements appearing above in this Note, and proceedings currently viewed as immaterial by us may ultimately materially impact us. Environmental Contingencies In connection with our largely historical operations, we have responded to or been notified of potential environmental liability at approximately 200 properties. We are engaged in addressing or have liquidated environmental liabilities at many of those properties. We could potentially be held liable, jointly, or severally, and without regard to fault, for the costs of investigation and remediation of these sites. The discovery of additional environmental liabilities or changes in existing environmental requirements could have a material adverse effect on our business. Capital Leases We lease certain facilities and equipment under various capital lease arrangements. Depreciation of assets under capital leases is included in depreciation and amortization expense in our consolidated statements of operations. Payments on capital leases are included in repayments of long-term debt, including current maturities in our consolidated statements of cash flows. The tables below summarize our capital lease activity: Years Ended December 31, 2018 2017 2016 (Dollars in millions) Assets acquired through capital leases $ 25 35 45 Depreciation expense 51 50 70 Cash payments towards capital leases 48 48 58 As of December 31, 2018 2017 (Dollars in millions) Assets included in property, plant and equipment $ 427 420 Accumulated depreciation 180 154 The future annual minimum payments under capital lease arrangements as of December 31, 2018 were as follows: Future Minimum Payments (Dollars in millions) Capital lease obligations: 2019 $ 51 2020 36 2021 23 2022 21 2023 20 2024 and thereafter 183 Total minimum payments 334 Less: amount representing interest and executory costs (100 ) Present value of minimum payments 234 Less: current portion (38 ) Long-term portion $ 196 Operating Lease Income CenturyLink leases various IRUs, office facilities, switching facilities and other network sites to third parties under operating leases. Lease and sublease income is included in operating revenue in the consolidated statements of operations. For the years ended December 31, 2018, 2017 and 2016, our gross rental income was $882 million , $766 million and $734 million , respectively. Right-of-Way and Operating Lease Expense CenturyLink leases various equipment, office facilities, retail outlets, switching facilities and other network sites. These leases, with few exceptions, provide for renewal options and escalations that are either fixed or based on the consumer price index. Any rent abatements, along with rent escalations, are included in the computation of rent expense calculated on a straight-line basis over the lease term. The lease term for most leases includes the initial non-cancelable term plus any term under renewal options that are reasonably assured. For the years ended December 31, 2018 , 2017 and 2016 , our gross rental expense was $875 million , $550 million and $482 million , respectively. We also received sublease rental income for the years ended December 31, 2018 , 2017 and 2016 of $21 million , $13 million and $12 million , respectively. At December 31, 2018 , our future rental commitments for Right-of-Way agreements and operating leases were as follows: Right-of-Way Agreements Operating Leases Total (Dollars in millions) 2019 157 675 832 2020 134 443 577 2021 112 355 467 2022 120 279 399 2023 115 241 356 2024 and thereafter 755 969 1,724 Total future minimum payments (1) 1,393 2,962 4,355 _______________________________________________________________________________ (1) Minimum payments have not been reduced by minimum sublease rentals of $101 million due in the future under non-cancelable subleases. Purchase Commitments We have several commitments primarily for marketing activities and support services from a variety of vendors to be used in the ordinary course of business totaling $921 million at December 31, 2018 . Of this amount, we expect to purchase $322 million in 2019 , $325 million in 2020 through 2021 , $88 million in 2022 through 2023 and $186 million in 2024 and thereafter . These amounts do not represent our entire anticipated purchases in the future, but represent only those items for which we were contractually committed as of December 31, 2018 .

Other Financial Information

Other Financial Information	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Other Financial Information	Other Financial Information Other Current Assets The following table presents details of other current assets in our consolidated balance sheets: As of December 31, 2018 2017 (Dollars in millions) Prepaid expenses $ 307 294 Income tax receivable 82 258 Materials, supplies and inventory 120 128 Contract assets 134 — Contract acquisition costs and deferred activation and installation charges 167 128 Other 108 133 Total other current assets $ 918 941 Selected Current Liabilities Current liabilities reflected in our consolidated balance sheets include accounts payable and other current liabilities as follows: As of December 31, 2018 2017 (Dollars in millions) Accounts payable $ 1,933 1,555 Other current liabilities: Accrued rent $ 45 34 Legal contingencies 30 45 Other 282 265 Total other current liabilities $ 357 344 Included in accounts payable at December 31, 2018 and 2017 , were (i) $86 million and $36 million , respectively, representing book overdrafts and (ii) $434 million and $225 million , respectively, associated with capital expenditures.

Labor Union Contracts

Labor Union Contracts	12 Months Ended
	Dec. 31, 2018
Risks and Uncertainties [Abstract]
Labor Union Contracts	Labor Union Contracts As of December 31, 2018 , approximately 26% of our employees were members of various bargaining units represented by the Communication Workers of America ("CWA") and the International Brotherhood of Electrical Workers ("IBEW"). We believe that relations with our employees continue to be generally good. Approximately 1% of our employees were subject to collective bargaining agreements that expired prior to December 31, 2018 and are currently being renegotiated. Approximately 2% of our employees are subject to collective bargaining agreements that are scheduled to expire in 2019.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Information Relating to 2018 The table below summarizes changes in accumulated other comprehensive loss recorded on our consolidated balance sheet by component for the year ended December 31, 2018 : Pension Plans Post-Retirement Benefit Plans Foreign Currency Translation Adjustment and Other Total (Dollars in millions) Balance at December 31, 2017 $ (1,731 ) (235 ) (29 ) (1,995 ) Other comprehensive loss before reclassifications (195 ) 194 (201 ) (202 ) Amounts reclassified from accumulated other comprehensive loss 128 15 — 143 Net current-period other comprehensive (loss) income (67 ) 209 (201 ) (59 ) Cumulative effect of adoption of ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (375 ) (32 ) — (407 ) Balance at December 31, 2018 $ (2,173 ) (58 ) (230 ) (2,461 ) The table below presents further information about our reclassifications out of accumulated other comprehensive loss by component for the year ended December 31, 2018 : Year Ended December 31, 2018 Decrease (Increase) in Net Loss Affected Line Item in Consolidated Statement of Operations (Dollars in millions) Amortization of pension & post-retirement plans (1) Net actuarial loss $ 178 Other income, net Prior service cost 12 Other income, net Total before tax 190 Income tax benefit (47 ) Income tax expense (benefit) Net of tax $ 143 ________________________________________________________________________ (1) See Note 10—Employee Benefits for additional information on our net periodic benefit (expense) income related to our pension and post-retirement plans. Information Relating to 2017 The table below summarizes changes in accumulated other comprehensive loss recorded on our consolidated balance sheet by component for the year ended December 31, 2017 : Pension Plans Post-Retirement Benefit Plans Foreign Currency Translation Adjustment and Other Total (Dollars in millions) Balance at December 31, 2016 $ (1,895 ) (162 ) (60 ) (2,117 ) Other comprehensive income (loss) before reclassifications 39 (86 ) 31 (16 ) Amounts reclassified from accumulated other comprehensive loss 125 13 — 138 Net current-period other comprehensive income (loss) 164 (73 ) 31 122 Balance at December 31, 2017 $ (1,731 ) (235 ) (29 ) (1,995 ) The table below presents further information about our reclassifications out of accumulated other comprehensive loss by component for the year ended December 31, 2017 : Year Ended December 31, 2017 Decrease (Increase) in Net Income Affected Line Item in Consolidated Statement of Operations (Dollars in millions) Amortization of pension & post-retirement plans (1) Net actuarial loss $ 205 Other income, net Prior service cost 12 Other income, net Total before tax 217 Income tax benefit (79 ) Income tax expense (benefit) Net of tax $ 138 ________________________________________________________________________ (1) See Note 10—Employee Benefits for additional information on our net periodic benefit (expense) income related to our pension and post-retirement plans.

Dividends

Dividends	12 Months Ended
	Dec. 31, 2018
Dividends, Common Stock [Abstract]
Dividends	Dividends Our Board of Directors declared the following dividends payable in 2018 and 2017 : Date Declared Record Date Dividend Per Share Total Amount Payment Date (in millions) November 14, 2018 11/26/2018 $ 0.540 $ 586 12/7/2018 August 21, 2018 8/31/2018 0.540 584 9/14/2018 May 23, 2018 6/4/2018 0.540 588 6/15/2018 February 21, 2018 3/5/2018 0.540 586 3/16/2018 November 14, 2017 11/27/2017 0.540 577 12/11/2017 August 22, 2017 9/5/2017 0.540 296 9/15/2017 May 24, 2017 6/5/2017 0.540 297 6/16/2017 February 21, 2017 3/3/2017 0.540 295 3/17/2017 The declaration of dividends is solely at the discretion of our Board of Directors, which may change or terminate our dividend practice at any time for any reason without prior notice. On March 1, 2019 , our Board of Directors declared a quarterly cash dividend of $0.25 per share.

Background and Summary of Sig_2

Background and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
General	General We are an international facilities-based communications company engaged primarily in providing a broad array of integrated services to our residential and business customers. On November 1, 2017, we acquired Level 3 Communications, Inc. ("Level 3") in a cash and stock transaction. See Note 2—Acquisition of Level 3 for additional information. On May 1, 2017, we sold our data centers and colocation business to a consortium of private equity purchasers for a combination of cash and equity. See Note 3—Sale of Data Centers and Colocation Business for additional information.
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include our accounts and the accounts of our subsidiaries in which we have a controlling interest. These subsidiaries include Level 3 on and after November 1, 2017. Intercompany amounts and transactions with our consolidated subsidiaries have been eliminated. In connection with our acquisition of Level 3, we acquired its deconsolidated Venezuela subsidiary and due to exchange restrictions and other conditions we have assigned no value to this subsidiary's assets. Additionally, we have excluded this subsidiary from our consolidated financial statements. To simplify the overall presentation of our consolidated financial statements, we report immaterial amounts attributable to noncontrolling interests in certain of our subsidiaries as follows: (i) income attributable to noncontrolling interests in other income, net, (ii) equity attributable to noncontrolling interests in additional paid-in capital and (iii) cash flows attributable to noncontrolling interests in other, net financing activities.
Reclassification	We reclassified certain prior period amounts to conform to the current period presentation, including the categorization of our revenue and our segment reporting for 2018 , 2017 and 2016 . See Note 15—Segment Information for additional information. These changes had no impact on total operating revenue, total operating expenses or net (loss) income for any period.
Use of Estimates	Use of Estimates Our consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles. These accounting principles require us to make certain estimates, judgments and assumptions. We believe that the estimates, judgments and assumptions we make when accounting for specific items and matters, including, but not limited to, revenue recognition, revenue reserves, network access costs, network access cost dispute reserves, investments, long-term contracts, customer retention patterns, allowance for doubtful accounts, depreciation, amortization, asset valuations, internal labor capitalization rates, recoverability of assets (including deferred tax assets), impairment assessments, pension, post-retirement and other post-employment benefits, taxes, certain liabilities and other provisions and contingencies, are reasonable, based on information available at the time they are made. These estimates, judgments and assumptions can materially affect the reported amounts of assets, liabilities and components of stockholders' equity as of the dates of the consolidated balance sheets, as well as the reported amounts of revenue, expenses and components of cash flows during the periods presented in our other consolidated financial statements. We also make estimates in our assessments of potential losses in relation to threatened or pending tax and legal matters. See Note 14—Income Taxes and Note 17—Commitments, Contingencies and Other Items for additional information. For matters not related to income taxes, if a loss is considered probable and the amount can be reasonably estimated, we recognize an expense for the estimated loss. If we have the potential to recover a portion of the estimated loss from a third party, we make a separate assessment of recoverability and reduce the estimated loss if recovery is also deemed probable. For matters related to income taxes, if we determine that the impact of an uncertain tax position is more likely than not to be sustained upon audit by the relevant taxing authority, then we recognize a benefit for the largest amount that is more likely than not to be sustained. No portion of an uncertain tax position will be recognized if the position has less than a 50% likelihood of being sustained. Interest is recognized on the amount of unrecognized benefit from uncertain tax positions. For all of these and other matters, actual results could differ materially from our estimates.
Revenue Recognition	Revenue Recognition We earn most of our consolidated revenue from contracts with customers, primarily through the provision of telecommunications and other services. Revenue from contracts with customers is accounted for under Accounting Standards Codification ("ASC") 606. We also earn revenue from leasing arrangements (primarily fiber capacity agreements) and governmental subsidy payments, neither of which are accounted for under ASC 606. Revenue is recognized when control of the promised goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to receive in exchange for those goods or services. Revenue is recognized based on the following five-step model: • Identification of the contract with a customer; • Identification of the performance obligations in the contract; • Determination of the transaction price; • Allocation of the transaction price to the performance obligations in the contract; and • Recognition of revenue when, or as, we satisfy a performance obligation. We provide an array of communications services to residential and business customers, including local voice, VPN, Ethernet, data, broadband, private line (including special access), network access, transport, voice, information technology, video and other ancillary services. We provide these services to a wide range of businesses, including global/international, enterprise, wholesale, government, small and medium business customers. Certain contracts also include the sale of equipment, which is not significant to our business. We recognize revenue for services when we provide the applicable service or when control is transferred. Recognition of certain payments received in advance of services being provided is deferred. These advance payments include certain activation and certain installation charges. If the activation and installation charges are not separate performance obligations, we recognize them as revenue over the actual or expected contract term using historical experience, which ranges from one year to seven years depending on the service. In most cases, termination fees or other fees on existing contracts that are negotiated in conjunction with new contracts are deferred and recognized over the new contract term. For access services, we generally bill fixed monthly charges one month in advance to customers and recognize revenue as service is provided over the contract term in alignment with the customer's receipt of service. For usage and other ancillary services, we generally bill in arrears and recognize revenue as usage or delivery occurs. In certain cases, customers may be permitted to modify their contracts. We evaluate the change in scope or price to identify whether the modification should be treated as a separate contract, whether the modification is a termination of the existing contract and creation of a new contract, or if it is a change to the existing contract. Customer contracts are evaluated to determine whether the performance obligations are separable. If the performance obligations are deemed separable and separate earnings processes exist, the total transaction price that we expect to receive with the customer is allocated to each performance obligation based on its relative standalone selling price. The revenue associated with each performance obligation is then recognized as earned. We periodically sell optical capacity on our network. These transactions are structured as indefeasible rights of use, commonly referred to as IRUs, which are the exclusive right to use a specified amount of capacity or fiber for a specified term, typically 10 to 20 years. In most cases, we account for the cash consideration received on transfers of optical capacity as ASC 606 revenue which we recognize ratably over the term of the agreement. Cash consideration received on transfers of dark fiber is adjusted for the time value of money and is accounted for as non-ASC 606 lease revenue, which we also recognize ratably over the term of the agreement. We do not recognize revenue on any contemporaneous exchanges of our optical capacity assets for other non-owned optical capacity assets. In connection with offering products and services provided to the end user by third-party vendors, we review the relationship between us, the vendor and the end user to assess whether revenue should be reported on a gross or net basis. In assessing whether revenue should be reported on a gross or net basis, we consider whether we act as a principal in the transaction and control the goods and services used to fulfill the performance obligations associated with the transaction. We have service level commitments pursuant to contracts with certain of our customers. To the extent that such service levels are not achieved or are otherwise disputed due to performance or service issues or other service interruptions or conditions, we will estimate the amount of credits to be issued and record a corresponding reduction to revenue in the period that the service level commitment was not met. Customer payments are made based on billing schedules included in our customer contracts, which is typically on a monthly basis. We defer (i.e. capitalize) incremental contract acquisition and fulfillment costs and recognize (or amortize) such costs over the average customer life. Our deferred contract costs for our customers have average amortization periods of approximately 30 months for consumer and up to 49 months for business. These deferred costs are monitored every period to reflect any significant change in assumptions. See Note 5—Revenue Recognition for additional information.
USF Surcharges, Gross Receipts Taxes and Other Surcharges	USF Surcharges, Gross Receipts Taxes and Other Surcharges In determining whether to include in our revenue and expenses the taxes and surcharges collected from customers and remitted to government authorities, including USF surcharges, sales, use, value added and some excise taxes, we assess, among other things, whether we are the primary obligor or principal taxpayer for the taxes assessed in each jurisdiction where we do business. In jurisdictions where we determine that we are the principal taxpayer, we record the surcharges on a gross basis and include them in our revenue and costs of services and products. In jurisdictions where we determine that we are merely a collection agent for the government authority, we record the taxes on a net basis and do not include them in our revenue and costs of services and products.
Advertising Costs	Advertising Costs Costs related to advertising are expensed as incurred and included in selling, general and administrative expenses in our consolidated statements of operations. Our advertising expense was $98 million , $218 million and $216 million for the years ended December 31, 2018 , 2017 and 2016 , respectively.
Legal Costs	Legal Costs In the normal course of our business, we incur costs to hire and retain external legal counsel to advise us on regulatory, litigation and other matters. We expense these costs as the related services are received.
Income Taxes	Income Taxes We file a consolidated federal income tax return with our eligible subsidiaries. The provision for income taxes consists of an amount for taxes currently payable, an amount for tax consequences deferred to future periods and adjustments to our liabilities for uncertain tax positions. We record deferred income tax assets and liabilities reflecting future tax consequences attributable to tax net operating loss carryforwards ("NOLs"), tax credit carryforwards and differences between the financial statement carrying value of assets and liabilities and the tax basis of those assets and liabilities. Deferred taxes are computed using enacted tax rates expected to apply in the year in which the differences are expected to affect taxable income. The effect on deferred income tax assets and liabilities of a change in tax rate is recognized in earnings in the period that includes the enactment date. We establish valuation allowances when necessary to reduce deferred income tax assets to the amounts that we believe are more likely than not to be recovered. Each quarter we evaluate the need to retain all or a portion of the valuation allowance on our deferred tax assets. See Note 14—Income Taxes for additional information.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents include highly liquid investments that are readily convertible into cash and are not subject to significant risk from fluctuations in interest rates. As a result, the value at which cash and cash equivalents are reported in our consolidated financial statements approximates their fair value. In evaluating investments for classification as cash equivalents, we require that individual securities have original maturities of ninety days or less and that individual investment funds have dollar-weighted average maturities of ninety days or less. To preserve capital and maintain liquidity, we invest with financial institutions we deem to be of sound financial condition and in high quality and relatively risk-free investment products. Our cash investment policy limits the concentration of investments with specific financial institutions or among certain products and includes criteria related to credit worthiness of any particular financial institution. Book overdrafts occur when checks have been issued but have not been presented to our controlled disbursement bank accounts for payment. Disbursement bank accounts allow us to delay funding of issued checks until the checks are presented for payment. Until the issued checks are presented for payment, the book overdrafts are included in accounts payable on our consolidated balance sheet. This activity is included in the operating activities section in our consolidated statements of cash flows.
Restricted Cash and Securities	Restricted Cash and Securities Restricted cash and securities consists primarily of cash and investments that serve to collateralize our outstanding letters of credit and certain performance and operating obligations. Restricted cash and securities are recorded as current or non-current assets in the consolidated balance sheets depending on the duration of the restriction and the purpose for which the restriction exists. Restricted securities are stated at cost which approximates fair value as of December 31, 2018 and 2017 .
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are recognized based upon the amount due from customers for the services provided or at cost for purchased and other receivables less an allowance for doubtful accounts. The allowance for doubtful accounts receivable reflects our best estimate of probable losses inherent in our receivable portfolio determined on the basis of historical experience, specific allowances for known troubled accounts and other currently available evidence. We generally consider our accounts past due if they are outstanding over 30 days . Our collection process varies by the customer segment, amount of the receivable, and our evaluation of the customer's credit risk. Our past due accounts are written off against our allowance for doubtful accounts when collection is considered to be not probable. Any recoveries of accounts previously written off are generally recognized as a reduction in bad debt expense in the period received. The carrying value of accounts receivable net of the allowance for doubtful accounts approximates fair value. Accounts receivable balances acquired in a business combination are recorded at fair value for all balances receivable at the acquisition date and at the invoiced amount for those amounts invoiced after the acquisition date.
Property, Plant and Equipment	Property, Plant and Equipment We record property, plant and equipment acquired in connection with our acquisitions based on its estimated fair value as of its acquisition date plus the estimated value of any associated legally or contractually required retirement obligations. We record purchased and constructed property, plant and equipment at cost, plus the estimated value of any associated legally or contractually required retirement obligations. The majority of our property, plant and equipment is depreciated using the straight-line group method, but certain of our assets are depreciated using the straight-line method over their estimated useful lives of the specific asset. Under the straight-line group method, assets dedicated to providing telecommunications services (which comprise the majority of our property, plant and equipment) that have similar physical characteristics, use and expected useful lives are pooled for purposes of depreciation and tracking. The equal life group procedure is used to establish each pool's average remaining useful life. Generally, under the straight-line group method, when an asset is sold or retired in the course of normal business activities, the cost is deducted from property, plant and equipment and charged to accumulated depreciation without recognition of a gain or loss. A gain or loss is recognized in our consolidated statements of operations only if a disposal is unusual. Leasehold improvements are amortized over the shorter of the useful lives of the assets or the expected lease term. Expenditures for maintenance and repairs are expensed as incurred. Interest is capitalized during the construction phase of network and other internal-use capital projects. Employee-related costs for construction of network and other internal use assets are also capitalized during the construction phase. Property, plant and equipment supplies used internally are carried at average cost, except for significant individual items for which cost is based on specific identification. We perform annual internal reviews to evaluate the reasonableness of the depreciable lives for our property, plant and equipment. Our reviews utilize models that take into account actual usage, physical wear and tear, replacement history, assumptions about technology evolution and, in certain instances, actuarially determined probabilities to estimate the remaining useful life of our asset base. Our remaining useful life assessments assess the possible loss in service value of assets that may precede the physical retirement. Assets shared among many customers may lose service value as those customers reduce their use of the asset. However, the asset is not retired until all customers no longer utilize the asset and we determine there is no alternative use for the asset. We have asset retirement obligations associated with the legally or contractually required removal of a limited group of property, plant and equipment assets from leased properties and the disposal of certain hazardous materials present in our owned properties. When an asset retirement obligation is identified, usually in association with the acquisition of the asset, we record the fair value of the obligation as a liability. The fair value of the obligation is also capitalized as property, plant and equipment and then amortized over the estimated remaining useful life of the associated asset. Where the removal obligation is not legally binding, the net cost to remove assets is expensed in the period in which the costs are actually incurred. Capitalized labor associated with employees and contract labor working on capital projects were approximately $569 million , $559 million and $524 million for the years ended December 31, 2018 , 2017 and 2016 .
Goodwill, Customer Relationships and Other Intangible Assets	Goodwill, Customer Relationships and Other Intangible Assets Intangible assets arising from business combinations, such as goodwill, customer relationships, capitalized software, trademarks and trade names, are initially recorded at estimated fair value. We amortize customer relationships primarily over an estimated life of 7 to 15 years , using either the sum-of-years-digits or the straight-line methods, depending on the type of customer. We amortize capitalized software using the straight-line method over estimated lives ranging up to 7 years , except for approximately $237 million of our capitalized software costs, which represents costs to develop an integrated billing and customer care system which is amortized using the straight-line method over a 20 -year period. We amortize our other intangible assets using the sum-of-years-digits or straight-line method over an estimated life of 4 to 20 years. Other intangible assets not arising from business combinations are initially recorded at cost. Where there are no legal, regulatory, contractual or other factors that would reasonably limit the useful life of an intangible asset, we classify the intangible asset as indefinite-lived and such intangible assets are not amortized. Internally used software, whether purchased or developed by us, is capitalized and amortized using the straight-line method over its estimated useful life. We have capitalized certain costs associated with software such as costs of employees devoting time to the projects and external direct costs for materials and services. Costs associated with software to be used for internal purposes are expensed until the point at which the project has reached the development stage. Subsequent additions, modifications or upgrades to internal-use software are capitalized only to the extent that they allow the software to perform a task it previously did not perform. Software maintenance, data conversion and training costs are expensed in the period in which they are incurred. We review the remaining economic lives of our capitalized software annually. Capitalized software is included in other intangible assets, net, in our consolidated balance sheets. Our long-lived intangible assets, other than goodwill, with indefinite lives are assessed for impairment annually, or, under certain circumstances, more frequently, such as when events or changes in circumstances indicate there may be an impairment. These assets are carried at the estimated fair value at the time of acquisition and assets not acquired in acquisitions are recorded at historical cost. However, if their estimated fair value is less than the carrying amount, we recognize an impairment charge for the amount by which the carrying amount of these assets exceeds their estimated fair value. We are required to assess goodwill for impairment at least annually, or more frequently, if an event occurs or circumstances change that would indicate an impairment may have occurred. We are required to write-down the value of goodwill in periods in which the recorded carrying value of equity exceeds the fair value of equity. Our reporting units are not discrete legal entities with discrete full financial statements. Therefore, the equity carrying value and future cash flows is assessed each time a goodwill impairment assessment is performed on a reporting unit. To do so, we assign our assets, liabilities and cash flows to reporting units using reasonable and consistent allocation methodologies, which entail various estimates, judgments and assumptions. We believe these estimates, judgments and assumptions to be reasonable, but changes in any of these can significantly affect each reporting unit's equity carrying value and future cash flows utilized for our goodwill impairment assessment. We are required to reassign goodwill to reporting units each time we reorganize our internal reporting structure which causes a change in the composition of our reporting units. Goodwill is reassigned to the reporting units using a relative fair value approach. When the fair value of a reporting unit is available, we allocate goodwill based on the relative fair value of the reporting units. When fair value is not available, we utilize the earnings before interest, taxes, depreciation and amortization of each reporting unit as our allocation methodology based on our view that it represents a reasonable proxy for the fair value of the operations being reorganized.
Subsequent Event	Subsequent Event As a result of organizational changes made in January 2019, we are making changes to our revenue reporting categories in 2019 to align them with how the business is managed. Our indirect channel, which primarily targets small to medium-sized enterprises, will move from the wholesale and indirect business unit. We are also moving state and local government customers from the small and medium business unit to the enterprise business unit to gain efficiencies by managing all government customers in a single organization. In addition, the new reporting structure reflects changes made to customer assignments between all five customer-facing business units. We are making changes to the service-type reporting to make it easier for management and investors to evaluate changes to consumer product revenue. We plan to report consumer revenue in the following categories: broadband; voice; regulatory (includes CAF II and other support funds); and other, which includes retail video and other miscellaneous services. We plan to maintain the structure of our business segment, with minor modifications.
Pension and Post-Retirement Benefits	Pension and Post-Retirement Benefits We recognize the funded status of our defined benefit and post-retirement plans as an asset or a liability on our consolidated balance sheet. Each year's actuarial gains or losses are a component of our other comprehensive income (loss), which is then included in our accumulated other comprehensive loss. Pension and post-retirement benefit expenses are recognized over the period in which the employee renders service and becomes eligible to receive benefits. We make significant assumptions (including the discount rate, expected rate of return on plan assets, mortality and health care trend rates) in computing the pension and post-retirement benefits expense and obligations. Note 10—Employee Benefits for additional information.
Foreign Currency	Foreign Currency Local currencies of foreign subsidiaries are the functional currencies for financial reporting purposes except for certain foreign subsidiaries, primarily in Latin America. For operations outside the United States that have functional currencies other than the U.S. dollar, assets and liabilities are translated to U.S. dollars at period-end exchange rates, and revenue, expenses and cash flows are translated using average monthly exchange rates. A significant portion of our non-United States subsidiaries have either the British pound, the euro or the Brazilian real as the functional currency, each of which experienced significant fluctuations against the U.S. dollar during the years ended December 31, 2018, 2017 and 2016. Foreign currency translation gains and losses are recognized as a component of accumulated other comprehensive loss in stockholders' equity and in the consolidated statements of comprehensive income (loss) in accordance with accounting guidance for foreign currency translation. We consider the majority of our investments in our foreign subsidiaries to be long-term in nature. Our foreign currency transaction gains (losses), including where transactions with our non-United States subsidiaries are not considered to be long-term in nature, are included within other income, net on the consolidated statements of operations.
Common Stock, Preferred Stock, Section 382 Rights Plan and Dividends	Common Stock At December 31, 2018 , we had 4 million unissued shares of CenturyLink, Inc. common stock reserved for acquisitions. In addition, we had 30 million shares authorized for future issuance under our equity incentive plans. Preferred Stock Holders of outstanding CenturyLink, Inc. preferred stock are entitled to receive cumulative dividends, receive preferential distributions equal to $25 per share plus unpaid dividends upon CenturyLink, Inc.'s liquidation and vote as a single class with the holders of common stock. Section 382 Rights Plan On February 13, 2019, we adopted a Section 382 Rights Plan to protect our U.S. federal net operating loss carryforwards from certain Internal Revenue Code Section 382 limitations. Under the plan, one preferred stock purchase right was distributed for each share of our outstanding common stock as of the close of business on February 25, 2019, and those rights currently trade in tandem with the common stock until they expire or detach under the plan. This plan was designed to deter trading that would result in a change of control (as defined in Code Section 382), and therefore protect our ability to use our historical federal net operating losses in the future. Dividends The declaration and payment of dividends is at the discretion of our Board of Directors.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements During 2018, we adopted Accounting Standards Update (“ASU”) 2014-09, “ Revenue from Contracts with Customers ”, ASU 2018-02, “ Income Statement-Reporting Comprehensive Income: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income ”, ASU 2016-16, “ Intra-Entity Transfers of Assets Other Than Inventory ”, ASU 2017-04, " Simplifying the Test for Goodwill Impairment" and ASU 2018-14, " Compensation-Retirement Benefits-Defined Benefit Plans-General: Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans ". Each of these is described further below. Revenue Recognition In May 2014, the FASB issued ASU 2014-09 which replaces virtually all existing generally accepted accounting principles on revenue recognition with a principles-based approach for determining revenue recognition using a new five step model. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 also includes new accounting principles related to the deferral and amortization of contract acquisition and fulfillment costs. We adopted the new revenue recognition standard under the modified retrospective transition method. During the year ended December 31, 2018, we recorded a cumulative catch-up adjustment that increased our retained earnings by $338 million , net of $119 million of income taxes. See Note 5—Revenue Recognition for additional information. Comprehensive Loss In February 2018, the FASB issued ASU 2018-02 provides an option to reclassify stranded tax effects within accumulated other comprehensive loss to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act (the "Act") (or portion thereof) is recorded. If an entity elects to reclassify the income tax effects of the Act, the amount of that reclassification shall include the effect of the change in the U.S. federal corporate income tax rate on the gross deferred tax amounts and related valuation allowances, if any, at the date of enactment of the Act related to items remaining in accumulated other comprehensive loss. The effect of the change in the U.S. federal corporate income tax rate on gross valuation allowances that were originally charged to income from continuing operations shall not be included. ASU 2018-02 is effective January 1, 2019, but early adoption is permitted and should be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Act is recognized. We early adopted and applied ASU 2018-02 in the first quarter of 2018. The adoption of ASU 2018-02 resulted in a $407 million increase to retained earnings and in accumulated other comprehensive loss. See Note 20—Accumulated Other Comprehensive Loss for additional information. Income Taxes In October 2016, the FASB issued ASU 2016-16, “ Intra-Entity Transfers of Assets Other Than Inventory” ("ASU 2016-16"). ASU 2016-16 eliminates the current prohibition on the recognition of the income tax effects on the transfer of assets among our subsidiaries. After adoption of ASU 2016-16, the income tax effects associated with these asset transfers, except for the transfer of inventory, will be recognized in the period the asset is transferred versus the current deferral and recognition upon either the sale of the asset to a third party or over the remaining useful life of the asset. We adopted ASU 2016-16 on January 1, 2018. The adoption of ASU 2016-16 did not have a material impact to our consolidated financial statements. Goodwill Impairment In January 2017, the FASB issued ASU 2017-04, “ Simplifying the Test for Goodwill Impairment ” (“ASU 2017-04”). ASU 2017-04 simplifies the impairment testing for goodwill by changing the measurement for goodwill impairment. Under current rules, we are required to compute the fair value of goodwill to measure the impairment amount if the carrying value of a reporting unit exceeds its fair value. Under ASU 2017-04, the goodwill impairment charge will equal the excess of the reporting unit carrying value above its fair value, limited to the amount of goodwill assigned to the reporting unit. We elected to early adopt the provisions of ASU 2017-04 as of October 1, 2018. We applied ASU 2017-04 to determine the impairment of $2.7 billion recorded during the fourth quarter of 2018. See Note 4 - Goodwill, Customer Relationships and Other Intangible Assets for additional information. Retirement Benefits In August 2018, the FASB issued ASU 2018-14, " Compensation-Retirement Benefits-Defined Benefit Plans-General: Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans " (“ASU 2018-14“). ASU 2018-14 eliminates requirements for certain disclosures that are not considered cost beneficial, clarifies certain required disclosures and adds additional disclosures under defined benefit pension plans and other postretirement plans. We adopted this guidance during the fourth quarter 2018. The adoption of ASU 2018-14 did not have a material impact to our consolidated financial statements. Recently Issued Accounting Pronouncements Financial Instruments In June 2016, the FASB issued ASU 2016-13, " Measurement of Credit Losses on Financial Instruments " ("ASU 2016-13"). The primary impact of ASU 2016-13 for us is a change in the model for the recognition of credit losses related to our financial instruments from an incurred loss model, which recognized credit losses only if it was probable that a loss had been incurred, to an expected loss model, which requires our management team to estimate the total credit losses expected on the portfolio of financial instruments. We are currently reviewing the requirements of the standard and evaluating the impact on our consolidated financial statements. We are required to adopt the provisions of ASU 2016-13 effective January 1, 2020, but could elect to early adopt the provisions as of January 1, 2019. We expect to adopt ASU 2016-13 on January 1, 2020 and recognize the impacts through a cumulative adjustment to retained earnings as of the date of adoption. Leases In February 2016, the FASB issued ASU 2016-02, “ Leases ” (“ASU 2016-02”), and associated ASUs related to ASU 842, Leases , which require organizations that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases. In addition, the new guidance will require disclosures to help investors and other financial statement users better understand the amount, timing and uncertainty of cash flows arising from leases. For leases where we are a lessee, the presentation and measurement of the assets and liabilities will depend on each lease’s classification as either a finance or operating lease. For leases where we are a lessor, the accounting remains largely unchanged from current U.S. GAAP but does contain some targeted improvements to align with the new revenue recognition guidance issued in 2014 (ASC 606). The new standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. We have a cross-functional team in place to evaluate and implement the new guidance and we have substantially completed the implementation of third-party software solutions to facilitate compliance with accounting and reporting requirements. The team continues to review existing lease arrangements and has collected and loaded a significant portion of our lease portfolio into the software. We continue to enhance accounting systems and update business processes and controls related to the new guidance for leases. Collectively, these activities are expected to facilitate our ability to meet the new accounting and disclosure requirements upon adoption in the first quarter of 2019. ASU 2016-02 requires a modified retrospective transition approach, applying the new standard to all leases existing at the date of initial adoption. An entity may choose to use either (1) the effective date or (2) the beginning of the earliest comparative period presented in the financial statements at the date of initial application. We will apply the transition requirements at the January 1, 2019 effective date by showing a cumulative effect adjustment in the first quarter of 2019, rather than restating any prior periods. In addition, we will elect the package of practical expedients permitted under the transition guidance, which does not require reassessment of prior conclusions related to contracts containing a lease, lease classification and initial direct lease costs. As an accounting policy election, we will exclude short-term leases (term of 12 months or less) from the balance sheet presentation and will account for non-lease and lease components in a contract as a single lease component for most asset classes. We are in the process of completing our adoption of ASU 2016-02, including reviewing our lease portfolio , completing the implementation and testing of the third-party software solution and exercising internal controls over adoption and implementation of ASU 2016-02. Therefore, the estimated impact on our consolidated balance sheet cannot currently be determined. However, we expect the adoption of ASU 2016-02 will have a material impact on our consolidated balance sheet through the recognition of right of use assets and lease liabilities for our operating leases. The impact to our consolidated statements of operations and consolidated statements of cash flows is not expected to be material. We believe the new standard will have no impact on our debt covenant compliance under our current agreements. We currently lease real estate, vehicles, dark fiber and a wide variety of equipment. In addition, deferred gains of approximately $115 million arising from prior period sales-leaseback transactions, which under prior accounting rules would have been recognized on our operating statements over an average period of three years , will be reflected through an adjustment to retained earnings on our balance sheet as of January 1, 2019. Upon implementing ASU 2016-02, accounting for the failed sale leaseback will no longer be applicable based on our facts and circumstances, and the real estate assets and corresponding financing obligation will be derecognized from our consolidated financial statements. Please see Note 3—Sale of Data Centers and Colocation Business for additional information on the accounting for the failed-sale-leaseback.

Background and Summary of Sig_3

Background and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The elimination of the failed leaseback will result in the following increase (decrease) to our balance sheet at January 1, 2019: Balance Sheet (Dollars in millions) Property, plant and equipment $ (409 ) Deferred rent (3 ) Long-term debt (558 ) Deferred income taxes 37 Stockholder's equity 115 The following tables present our reported results under ASC 606 and a reconciliation to results using the historical accounting method: Year Ended December 31, 2018 Reported Balances Impact of ASC 606 ASC 605 Historical Adjusted Balances (Dollars in millions, except per share amounts and shares in thousands) Operating revenue $ 23,443 39 23,482 Cost of services and products (exclusive of depreciation and amortization) 10,862 22 10,884 Selling, general and administrative 4,165 71 4,236 Interest expense 2,177 (9 ) 2,168 Income tax expense 170 (12 ) 158 Net loss (1,733 ) (33 ) (1,766 ) BASIC AND DILUTED LOSS PER COMMON SHARE BASIC $ (1.63 ) (0.03 ) (1.66 ) DILUTED $ (1.63 ) (0.03 ) (1.66 ) WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING BASIC 1,065,866 — 1,065,866 DILUTED 1,065,866 — 1,065,866 The following table presents a reconciliation of certain consolidated balance sheet captions under ASC 606 to the balance sheet results using the historical accounting method: As of December 31, 2018 Reported Balances Impact of ASC 606 ASC 605 Historical Adjusted Balances (Dollars in millions) Other current assets $ 918 (172 ) 746 Other long-term assets, net 1,060 (112 ) 948 Deferred revenue 2,375 71 2,446 Deferred income taxes, net 2,395 (131 ) 2,264 Other long-term liabilities 1,099 147 1,246 Accumulated deficit (1,643 ) (371 ) (2,014 )

Acquisition of Level 3 (Tables)

Acquisition of Level 3 (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisition of Level 3	The following is our assignment of the aggregate consideration: Adjusted November 1, 2017 Balance as of December 31, 2017 Purchase Price Adjustments Adjusted November 1, 2017 Balance as of October 31, 2018 (Dollars in millions) Cash, accounts receivable and other current assets (1) $ 3,317 (26 ) 3,291 Property, plant and equipment 9,311 157 9,468 Identifiable intangible assets (2) Customer relationships 8,964 (533 ) 8,431 Other 391 (13 ) 378 Other noncurrent assets 782 216 998 Current liabilities, excluding current maturities of long-term debt (1,461 ) (32 ) (1,493 ) Current maturities of long-term debt (7 ) — (7 ) Long-term debt (10,888 ) — (10,888 ) Deferred revenue and other liabilities (1,629 ) (114 ) (1,743 ) Goodwill 10,837 340 11,177 Total estimated aggregate consideration $ 19,617 (5 ) 19,612 ____________________________________________________________________________________________________________ (1) Includes accounts receivable, which had a gross contractual value of $884 million on November 1, 2017 and October 31, 2018. (2) The weighted-average amortization period for the acquired intangible assets is approximately 12.0 years .
Summary of Acquisition Related Expenses	The table below summarizes our acquisition-related expenses, which consist of integration-related expenses, including severance and retention compensation expenses, and transaction-related expenses: Years Ended December 31, 2018 2017 (Dollars in millions) Transaction-related expenses $ 2 174 Integration-related expenses 391 97 Total acquisition-related expenses $ 393 271

Sale of Data Centers and Colo_2

Sale of Data Centers and Colocation Business (Tables)	12 Months Ended
	Dec. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Schedule of disposal assets held-for-sale and liabilities attributable to disposal assets held-for-sale	The following table reflects the assets sold to and the liabilities assumed by Cyxtera on May 1, 2017, including the impact of failed-sale-leaseback: Dollars in millions Goodwill $ 1,142 Property, plant and equipment 1,051 Other intangible assets 249 Other assets 66 Less assets not removed as a result of the failed-sale-leaseback (526 ) Total net amount of assets derecognized $ 1,982 Capital lease obligations $ 294 Other liabilities 274 Less imputed financing obligations from the failed-sale-leaseback (628 ) Total net imputed liabilities recognized $ (60 )
Sale-leaseback transactions	In addition, the failed-sale-leaseback accounting treatment had the following effects on our consolidated results of operations for the years ended December 31, 2018 and 2017 : Positive (Negative) Impact to Net Income December 31, 2018 2017 (Dollars in millions) Increase in revenue $ 74 49 Decrease in cost of sales 22 15 Increase in loss on sale of business included in selling, general and administrative expense — (102 ) Increase in depreciation expense (one-time) — (44 ) Increase in depreciation expense (ongoing) (69 ) (47 ) Increase in interest expense (55 ) (39 ) Decrease in income tax expense 7 65 Decrease in net income $ (21 ) (103 )

Goodwill, Customer Relationsh_2

Goodwill, Customer Relationships and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill and other intangible assets	Goodwill, customer relationships and other intangible assets consisted of the following: As of December 31, 2018 2017 (Dollars in millions) Goodwill $ 28,031 30,475 Customer relationships, less accumulated amortization of $8,492 and $7,096 $ 8,911 10,876 Indefinite-life intangible assets $ 269 269 Other intangible assets subject to amortization: Capitalized software, less accumulated amortization of $2,616 and $2,294 $ 1,468 1,469 Trade names, less accumulated amortization of $61 and $31 131 159 Total other intangible assets, net $ 1,868 1,897
Schedule of estimated amortization expense for intangible assets	We estimate that total amortization expense for intangible assets for the years ending December 31, 2019 through 2023 will be as follows: (Dollars in millions) 2019 $ 1,691 2020 1,589 2021 1,156 2022 985 2023 893
Schedule of goodwill attributable to segments	The following table shows the rollforward of goodwill assigned to our reportable segments from December 31, 2016 through December 31, 2018 . Business Consumer Total (Dollars in millions) As of December 31, 2016 (1) $ 9,372 10,278 19,650 Purchase accounting and other adjustments 10,825 — 10,825 As of December 31, 2017 (1) 20,197 10,278 30,475 Purchase accounting and other adjustments (2)(3) 250 32 282 Impairment — (2,726 ) (2,726 ) As of December 31, 2018 $ 20,447 7,584 $ 28,031 _____________________________________________________________________________ (1) Goodwill is net of accumulated impairment losses of $1.1 billion that related to our former hosting segment now included in our business segment. (2) We allocated $32 million of Level 3 goodwill to consumer as we expect the consumer segment to benefit from synergies resulting from the business combination. (3) Includes $58 million decrease due to effect of foreign currency exchange rate change. As of December 31, 2018 , our goodwill has been allocated to our reporting units as follows: (Dollars in millions) Medium and small business $ 5,193 Enterprise 5,222 International and global accounts 3,596 Wholesale and indirect 6,436 Total business segment 20,447 Consumer 7,584 Total goodwill $ 28,031

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The elimination of the failed leaseback will result in the following increase (decrease) to our balance sheet at January 1, 2019: Balance Sheet (Dollars in millions) Property, plant and equipment $ (409 ) Deferred rent (3 ) Long-term debt (558 ) Deferred income taxes 37 Stockholder's equity 115 The following tables present our reported results under ASC 606 and a reconciliation to results using the historical accounting method: Year Ended December 31, 2018 Reported Balances Impact of ASC 606 ASC 605 Historical Adjusted Balances (Dollars in millions, except per share amounts and shares in thousands) Operating revenue $ 23,443 39 23,482 Cost of services and products (exclusive of depreciation and amortization) 10,862 22 10,884 Selling, general and administrative 4,165 71 4,236 Interest expense 2,177 (9 ) 2,168 Income tax expense 170 (12 ) 158 Net loss (1,733 ) (33 ) (1,766 ) BASIC AND DILUTED LOSS PER COMMON SHARE BASIC $ (1.63 ) (0.03 ) (1.66 ) DILUTED $ (1.63 ) (0.03 ) (1.66 ) WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING BASIC 1,065,866 — 1,065,866 DILUTED 1,065,866 — 1,065,866 The following table presents a reconciliation of certain consolidated balance sheet captions under ASC 606 to the balance sheet results using the historical accounting method: As of December 31, 2018 Reported Balances Impact of ASC 606 ASC 605 Historical Adjusted Balances (Dollars in millions) Other current assets $ 918 (172 ) 746 Other long-term assets, net 1,060 (112 ) 948 Deferred revenue 2,375 71 2,446 Deferred income taxes, net 2,395 (131 ) 2,264 Other long-term liabilities 1,099 147 1,246 Accumulated deficit (1,643 ) (371 ) (2,014 )
Disaggregation of Revenue	The following tables provide disaggregation of revenue from contracts with customers based on service offerings for the year ended December 31, 2018, respectively. It also shows the amount of revenue that is not subject to ASC 606, but is instead governed by other accounting standards. Year Ended December 31, 2018 Total Revenue Adjustments for Non-ASC 606 Revenue (8) Total Revenue from Contracts with Customers (Dollars in millions) Business segment IP and Data Services (1) $ 6,971 — 6,971 Transport and Infrastructure (2) 5,356 (569 ) 4,787 Voice and Collaboration (3) 4,401 — 4,401 IT and Managed Services (4) 621 — 621 Total business segment revenue 17,349 (569 ) 16,780 Consumer segment IP and Data Services (5) 308 (33 ) 275 Transport and Infrastructure (6) 2,892 (213 ) 2,679 Voice and Collaboration (3) 2,171 — 2,171 Total consumer segment revenue 5,371 (246 ) 5,125 Non-segment revenue Regulatory Revenue (7) 723 (723 ) — Total non-segment revenue 723 (723 ) — Total revenue $ 23,443 (1,538 ) 21,905 Timing of Revenue Goods and services transferred at a point in time $ 230 Services performed over time 21,675 Total revenue from contracts with customers $ 21,905 (1 ) Includes primarily VPN data network, Ethernet, IP, video and ancillary revenue. (2 ) Includes primarily broadband, private line (including business data services), colocation and data centers, wavelength and ancillary revenue. (3 ) Includes local, long-distance and other ancillary revenue. (4 ) Includes IT services and managed services revenue. (5 ) Includes retail video revenue (including our facilities-based video revenue). (6 ) Includes primarily broadband and equipment sales and professional services revenue. (7 ) Includes CAF Phase I, CAF Phase II, federal and state USF support revenue, sublease rental income and failed-sale leaseback income. (8 ) Includes regulatory revenue, lease revenue, sublease rental income, revenue from fiber capacity lease arrangements and failed sale leaseback income, which are not within the scope of ASC 606.
Contract with Customer, Asset and Liability	The following table provides balances of customer receivables, contract assets and contract liabilities as of December 31, 2018 and January 1, 2018: December 31, 2018 January 1, 2018 (Dollars in millions) Customer receivables (1) $ 2,346 2,504 Contract liabilities 860 904 Contract assets 140 145 (1 ) Gross customer receivables of $2.5 billion and $2.7 billion, net of allowance for doubtful accounts of $132 million and $155 million, at December 31, 2018 and January 1, 2018, respectively. The following table provides information about revenue recognized for the year ended December 31, 2018 : (Dollars in millions) Revenue recognized in the period from: Amounts included in contract liability at the beginning of the period (January 1, 2018) $ 295 Performance obligations satisfied in previous periods —
Capitalized Contract Cost	The following table provides changes in our contract acquisition costs and fulfillment costs: Year Ended December 31, 2018 Acquisition Costs Fulfillment Costs (Dollars in millions) Beginning of period balance $ 268 133 Costs incurred 226 146 Amortization (172 ) (92 ) End of period balance $ 322 187

Long-Term Debt and Credit Fac_2

Long-Term Debt and Credit Facilities (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of long-term debt including unamortized discounts and premiums	The following chart reflects the consolidated long-term debt of CenturyLink, Inc. and its subsidiaries, including unamortized discounts and premiums and unamortized debt issuance costs, but excluding intercompany debt: As of December 31, Interest Rates (1) Maturities 2018 2017 (Dollars in millions) Senior Secured Debt: (2) CenturyLink, Inc. 2017 Revolving Credit Facility (3) 5.130% - 7.250% 2022 $ 550 405 Term Loan A 5.272% 2022 1,622 1,575 Term Loan A-1 5.272% 2022 351 370 Term Loan B 5.272% 2025 5,940 6,000 Subsidiaries: Level 3 Financing, Inc. Tranche B 2024 Term Loan (4) 4.754% 2024 4,611 4,611 Embarq Corporation subsidiaries First mortgage bonds 7.125% - 8.375% 2023 - 2025 138 151 Senior Notes and Other Debt: CenturyLink, Inc. Senior notes 5.625% - 7.650% 2019 - 2042 8,036 8,125 Subsidiaries: Level 3 Financing, Inc. Senior notes 5.125% - 6.125% 2021 - 2026 5,315 5,315 Level 3 Parent, LLC Senior notes 5.750% 2022 600 600 Qwest Corporation Senior notes 6.125% - 7.750% 2021 - 2057 5,956 7,294 Term loan 4.530% 2025 100 100 Qwest Capital Funding, Inc. Senior notes 6.875% - 7.750% 2021 - 2031 697 981 Embarq Corporation and subsidiary Senior note 7.995% 2036 1,485 1,485 Other 9.000% 2019 150 150 Capital lease and other obligations Various Various 801 891 Unamortized (discounts) premiums and other, net (8 ) 23 Unamortized debt issuance costs (283 ) (350 ) Total long-term debt 36,061 37,726 Less current maturities (652 ) (443 ) Long-term debt, excluding current maturities $ 35,409 37,283 _______________________________________________________________________________ (1) As of December 31, 2018 . (2) See the remainder of this Note for a description of certain parent or subsidiary guarantees and liens securing this debt. (3) The aggregate amount outstanding on our 2017 revolving credit facility at December 31, 2018 was $550 million with a weighted-average interest rate of 5.322% . These amounts typically change on a regular basis. (4) The Tranche B 2024 Term Loan had an interest rate of 4.754% as of December 31, 2018 and 3.557% as of December 31, 2017 .
Schedule of maturities of long-term debt	Set forth below is the aggregate principal amount of our long-term debt (excluding unamortized discounts and premiums, net and unamortized debt issuance costs) maturing during the following years: (Dollars in millions) (1) 2019 $ 652 2020 1,205 2021 3,115 2022 5,283 2023 2,096 2024 and thereafter 23,503 Total long-term debt $ 35,854 _______________________________________________________________________________ (1) In Note 3—Sale of Data Centers and Colocation Business, we describe an imputed financing obligation. The amount outstanding on that imputed financing obligation at December 31, 2018 was $558 million . The aggregate maturities of long-term debt do not include $499 million of this obligation, which prior to the end of the lease term on April 30, 2020, will be derecognized along with the remaining net book value of the associated real estate assets.
Schedule of amount of gross interest expense, net of capitalized interest	Interest expense includes interest on total long-term debt. The following table presents the amount of gross interest expense, net of capitalized interest: Years Ended December 31, 2018 2017 2016 (Dollars in millions) Interest expense: Gross interest expense $ 2,230 1,559 1,372 Capitalized interest (53 ) (78 ) (54 ) Total interest expense $ 2,177 1,481 1,318

Accounts Receivable (Tables)

Accounts Receivable (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Schedule of components of accounts receivable	The following table presents details of our accounts receivable balances: As of December 31, 2018 2017 (Dollars in millions) Trade and purchased receivables $ 2,094 2,245 Earned and unbilled receivables 425 436 Other 21 40 Total accounts receivable 2,540 2,721 Less: allowance for doubtful accounts (142 ) (164 ) Accounts receivable, less allowance $ 2,398 2,557
Schedule of details of allowance for doubtful accounts	The following table presents details of our allowance for doubtful accounts: Beginning Balance Additions Deductions Ending Balance (Dollars in millions) 2018 $ 164 153 (175 ) 142 2017 178 176 (190 ) 164 2016 152 192 (166 ) 178

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule of net property, plant and equipment	Net property, plant and equipment is composed of the following: Depreciable Lives As of December 31, 2018 2017 (Dollars in millions) Land N/A $ 871 883 Fiber, conduit and other outside plant (1) 15-45 years 23,936 22,798 Central office and other network electronics (2) 3-10 years 18,736 18,538 Support assets (3) 3-30 years 8,020 7,586 Construction in progress (4) N/A 1,704 1,399 Gross property, plant and equipment 53,267 51,204 Accumulated depreciation (26,859 ) (24,352 ) Net property, plant and equipment $ 26,408 26,852 _______________________________________________________________________________ (1) Fiber, conduit and other outside plant consists of fiber and metallic cable, conduit, poles and other supporting structures. (2) Central office and other network electronics consists of circuit and packet switches, routers, transmission electronics and electronics providing service to customers. (3) Support assets consist of buildings, cable landing stations, data centers, computers and other administrative and support equipment. (4) Construction in progress includes inventory held for construction and property of the aforementioned categories that has not been placed in service as it is still under construction.
Schedule of changes to asset retirement obligations	The following table provides asset retirement obligation activity: Years Ended December 31, 2018 2017 2016 (Dollars in millions) Balance at beginning of year $ 115 95 91 Accretion expense 10 6 6 Liabilities assumed in acquisition of Level 3 (1) 58 45 — Liabilities settled (14 ) (3 ) (2 ) Liabilities transferred to Cyxtera — (20 ) — Change in estimate 21 (8 ) — Balance at end of year $ 190 115 95 (1) The liabilities assumed during 2018 relate to purchase price adjustments during the year.

Severance and Leased Real Est_2

Severance and Leased Real Estate (Tables)	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Schedule of changes in accrued liabilities for severance expenses and leased real estate	Changes in our accrued liabilities for severance expenses and leased real estate were as follows: Severance Real Estate (Dollars in millions) Balance at December 31, 2016 $ 98 67 Accrued to expense 42 4 Liabilities assumed in acquisition of Level 3 1 4 Payments, net (108 ) (13 ) Reversals and adjustments — 2 Balance at December 31, 2017 33 64 Accrued to expense 205 70 Payments, net (151 ) (24 ) Balance at December 31, 2018 $ 87 110

Employee Benefits (Tables)

Employee Benefits (Tables)	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Schedule of estimated future benefit payments	The Combined Pension Plan payments, post-retirement health care benefit payments and premiums, and life insurance premium payments are either distributed from plan assets or paid by us. The estimated benefit payments provided below are based on actuarial assumptions using the demographics of the employee and retiree populations and have been reduced by estimated participant contributions. Combined Pension Plan Post-Retirement Benefit Plans Medicare Part D Subsidy Receipts (Dollars in millions) Estimated future benefit payments: 2019 $ 966 277 (7 ) 2020 938 269 (7 ) 2021 916 261 (7 ) 2022 891 252 (7 ) 2023 867 243 (6 ) 2024 - 2028 3,971 1,065 (26 )
Schedule of actuarial assumptions used to compute net periodic benefit expense	The actuarial assumptions used to compute the net periodic benefit expense for our Combined Pension Plan and post-retirement benefit plans are based upon information available as of the beginning of the year, as presented in the following table. Combined Pension Plan Post-Retirement Benefit Plans 2018 2017 2016 2018 2017 2016 Actuarial assumptions at beginning of year: Discount rate 3.14% - 3.69% 3.25% - 4.14% 3.34% - 4.46% 4.26 % 3.90 % 4.15 % Rate of compensation increase 3.25 % 3.25 % 3.25 % N/A N/A N/A Expected long-term rate of return on plan assets (1) 6.50 % 6.50 % 7.00 % 4.00 % 5.00 % 7.00 % Initial health care cost trend rate N/A N/A N/A 7.00% / 5.00% 7.00% / 5.00% 5.00% / 5.25% Ultimate health care cost trend rate N/A N/A N/A 4.50 % 4.50 % 4.50 % Year ultimate trend rate is reached N/A N/A N/A 2025 2025 2025 _______________________________________________________________________________ N/A - Not applicable (1) Rates are presented net of projected fees and administrative costs.
Schedule of components of net periodic pension income and post-retirement benefit expense	Net periodic benefit (income) expense for our combined pension plan includes the following components: Combined Pension Plan Years Ended December 31, 2018 2017 2016 (Dollars in millions) Service cost $ 66 63 64 Interest cost 392 409 425 Expected return on plan assets (685 ) (666 ) (733 ) Special termination benefits charge 15 — 13 Recognition of prior service credit (8 ) (8 ) (8 ) Recognition of actuarial loss 178 204 174 Net periodic pension benefit (income) expense $ (42 ) 2 (65 ) Net periodic benefit expense for our post-retirement benefit plans includes the following components: Post-Retirement Plans Years Ended December 31, 2018 2017 2016 (Dollars in millions) Service cost $ 18 18 19 Interest cost 97 100 111 Expected return on plan assets (1 ) (2 ) (7 ) Special termination benefits charge — — 3 Recognition of prior service cost 20 20 20 Net periodic post-retirement benefit expense $ 134 136 146
Schedule of actuarial assumptions used to compute the funded status for the plans	The actuarial assumptions used to compute the funded status for the plans are based upon information available as of December 31, 2018 and 2017 and are as follows: Combined Pension Plan Post-Retirement Benefit Plans December 31, December 31, 2018 2017 2018 2017 Actuarial assumptions at end of year: Discount rate 4.29 % 3.57 % 4.26 % 3.53 % Rate of compensation increase 3.25 % 3.25 % N/A N/A Initial health care cost trend rate N/A N/A 7.00% / 5.00% 7.00% / 5.00% Ultimate health care cost trend rate N/A N/A 4.50 % 4.50 % Year ultimate trend rate is reached N/A N/A 2025 2025 _______________________________________________________________________________ N/A - Not applicable
Schedule of change in benefit obligation	The following tables summarize the change in the benefit obligations for the Combined Pension Plan and post-retirement benefit plans: Combined Pension Plan Years Ended December 31, 2018 2017 2016 (Dollars in millions) Change in benefit obligation Benefit obligation at beginning of year $ 13,064 13,244 13,287 Service cost 66 63 64 Interest cost 392 409 425 Plan amendments — — 2 Special termination benefits charge 15 — 13 Actuarial (gain) loss (765 ) 586 487 Benefits paid by company — — — Benefits paid from plan assets (1,178 ) (1,238 ) (1,034 ) Benefit obligation at end of year $ 11,594 13,064 13,244 Post-Retirement Benefit Plans Years Ended December 31, 2018 2017 2016 (Dollars in millions) Change in benefit obligation Benefit obligation at beginning of year $ 3,375 3,413 3,567 Service cost 18 18 19 Interest cost 97 100 111 Participant contributions 54 54 57 Direct subsidy receipts 8 7 5 Special termination benefits charge — — 3 Plan Amendment (36 ) — — Actuarial (gain) loss (224 ) 112 (13 ) Benefits paid by company (311 ) (298 ) (191 ) Benefits paid from plan assets (4 ) (31 ) (145 ) Benefit obligation at end of year $ 2,977 3,375 3,413
Schedule of change in plan assets	The following tables summarize the change in the fair value of plan assets for the Combined Pension Plan and post-retirement benefit plans: Combined Pension Plan Years Ended December 31, 2018 2017 2016 (Dollars in millions) Change in plan assets Fair value of plan assets at beginning of year $ 11,060 10,892 11,072 Return on plan assets (349 ) 1,306 754 Employer contributions 500 100 100 Benefits paid from plan assets (1,178 ) (1,238 ) (1,034 ) Fair value of plan assets at end of year $ 10,033 11,060 10,892 Post-Retirement Benefit Plans Years Ended December 31, 2018 2017 2016 (Dollars in millions) Change in plan assets Fair value of plan assets at beginning of year $ 23 53 193 Return on plan assets (1 ) 1 5 Benefits paid from plan assets (4 ) (31 ) (145 ) Fair value of plan assets at end of year $ 18 23 53
Schedule of gross notional exposure of the derivative instruments directly held by the plans	Gross Notional Exposure Combined Pension Plan Years Ended December 31, 2018 2017 (Dollars in millions) Derivative instruments: Exchange-traded U.S. equity futures $ 300 256 Exchange-traded Treasury and other interest rate futures 3,901 1,830 Interest rate swaps 83 137 Credit default swaps 66 100 Equity index swaps — 1 Foreign exchange forwards 295 293 Options 192 259
Schedule of fair value of the plans' assets by asset category	The tables below present the fair value of plan assets by category and the input levels used to determine those fair values at December 31, 2018 . It is important to note that the asset allocations do not include market exposures that are gained with derivatives. Investments include dividend and interest receivables, pending trades and accrued expenses. Fair Value of Combined Pension Plan Assets at December 31, 2018 Level 1 Level 2 Level 3 Total (Dollars in millions) Investment grade bonds (a) $ 458 1,393 — $ 1,851 High yield bonds (b) — 277 7 284 Emerging market bonds (c) 151 181 — 332 U.S. stocks (e) 764 2 2 768 Non-U.S. stocks (f) 601 — — 601 Private debt (i) — — 15 15 Multi-asset strategies (l) 342 — — 342 Derivatives (m) 7 (2 ) — 5 Cash equivalents and short-term investments (n) 3 907 — 910 Total investments, excluding investments valued at NAV $ 2,326 2,758 24 5,108 Investments valued at NAV 4,925 Total pension plan assets $ 10,033 Fair Value of Post-Retirement Plan Assets at December 31, 2018 Level 1 Level 2 Level 3 Total (Dollars in millions) Total investments, excluding investments valued at NAV $ — — — — Investments valued at NAV 18 Total post-retirement plan assets $ 18 The tables below present the fair value of plan assets by category and the input levels used to determine those fair values at December 31, 2017 . It is important to note that the asset allocations do not include market exposures that are gained with derivatives. Investments include dividend and interest receivable, pending trades and accrued expenses. Fair Value of Combined Pension Plan Assets at December 31, 2017 Level 1 Level 2 Level 3 Total (Dollars in millions) Investment grade bonds (a) $ 432 1,315 — $ 1,747 High yield bonds (b) — 575 7 582 Emerging market bonds (c) 217 219 1 437 U.S. stocks (e) 1,030 2 3 1,035 Non-U.S. stocks (f) 706 — — 706 Private debt (i) — — 15 15 Multi-asset strategies (l) 440 — — 440 Derivatives (m) 2 — — 2 Cash equivalents and short-term investments (n) — 476 1 477 Total investments, excluding investments valued at NAV $ 2,827 2,587 27 5,441 Investments valued at NAV 5,619 Total pension plan assets $ 11,060 Fair Value of Post-Retirement Plan Assets Level 1 Level 2 Level 3 Total (Dollars in millions) U.S. stocks (e) 1 — — 1 Total investments, excluding investments valued at NAV $ 1 — — 1 Investments valued at NAV 22 Total post-retirement plan assets $ 23 The table below presents the fair value of plan assets valued at NAV by category for our pension and post-retirement plans at December 31, 2018 and 2017 . Fair Value of Plan Assets Valued at NAV Combined Pension Plan at December 31, Post-Retirement Benefit Plans at December 31, 2018 2017 2018 2017 (Dollars in millions) Investment grade bonds (a) $ 109 163 — — High yield bonds (b) 388 483 — — Emerging market bonds (c) — 14 — — Diversified strategies (d) — 538 — — U.S. stocks (e) 150 73 — — Non-U.S. stocks (f) 500 627 — — Emerging market stocks (g) 75 98 — — Private equity (h) 347 460 6 10 Private debt (i) 452 374 1 1 Market neutral hedge funds (j) 746 769 — — Directional hedge funds (j) 512 636 — — Real estate (k) 821 903 — 1 Multi-asset strategies (l) 763 424 — — Cash equivalents and short-term investments (n) 62 57 11 10 Total investments valued at NAV $ 4,925 5,619 18 22
Summary of changes in fair value of defined benefit plans' Level 3 assets	The table below presents a rollforward of the pension plan assets valued using Level 3 inputs: Combined Pension Plan Assets Valued Using Level 3 Inputs High Yield Bonds Emerging Market Bonds U.S. Stocks Private Debt Cash Total (Dollars in millions) Balance at December 31, 2016 $ 11 — — — — 11 Net transfers (1 ) — — 14 — 13 Acquisitions 2 1 — 1 1 5 Dispositions (5 ) — 3 — — (2 ) Balance at December 31, 2017 7 1 3 15 1 27 Dispositions — — (2 ) — (1 ) (3 ) Actual return on plan assets — (1 ) 1 — — — Balance at December 31, 2018 $ 7 — 2 15 — 24
Schedule of the unfunded status of the benefit plans	The following table presents the unfunded status of the Combined Pension Plan and post-retirement benefit plans: Combined Pension Plan Post-Retirement Benefit Plans Years Ended December 31, Years Ended December 31, 2018 2017 2018 2017 (Dollars in millions) Benefit obligation $ (11,594 ) (13,064 ) (2,977 ) (3,375 ) Fair value of plan assets 10,033 11,060 18 23 Unfunded status (1,561 ) (2,004 ) (2,959 ) (3,352 ) Current portion of unfunded status — — (252 ) (262 ) Non-current portion of unfunded status $ (1,561 ) (2,004 ) (2,707 ) (3,090 )
Schedule of items not recognized as a component of net periodic benefits expense	The following table presents cumulative items not recognized as a component of net periodic benefits expense as of December 31, 2017 , items recognized as a component of net periodic benefits expense in 2018 , additional items deferred during 2018 and cumulative items not recognized as a component of net periodic benefits expense as of December 31, 2018 . The items not recognized as a component of net periodic benefits expense have been recorded on our consolidated balance sheets in accumulated other comprehensive loss: As of and for the Years Ended December 31, 2017 Recognition of Net Periodic Benefits Expense Deferrals Net Change in AOCL 2018 (Dollars in millions) Accumulated other comprehensive loss: Pension plans: Net actuarial (loss) gain $ (2,892 ) 179 (260 ) (81 ) (2,973 ) Prior service benefit (cost) 54 (8 ) — (8 ) 46 Deferred income tax benefit (expense) (1) 1,107 (418 ) 65 (353 ) 754 Total pension plans (1,731 ) (247 ) (195 ) (442 ) (2,173 ) Post-retirement benefit plans: Net actuarial (loss) gain (250 ) — 257 257 7 Prior service (cost) benefit (107 ) 20 — 20 (87 ) Deferred income tax benefit (expense) (2) 122 (37 ) (63 ) (100 ) 22 Total post-retirement benefit plans (235 ) (17 ) 194 177 (58 ) Total accumulated other comprehensive loss $ (1,966 ) (264 ) (1 ) (265 ) (2,231 ) _______________________________________________________________________________ (1) Amounts currently recognized in net periodic benefits expense include $375 million of benefit arising from the adoption of ASU 2018-02. See Note 1— Background and Summary of Significant Accounting Policies for further detail. (2) Amounts currently recognized in net periodic benefits expense include $32 million arising from the adoption of ASU 2018-02. See Note 1— Background and Summary of Significant Accounting Policies for further detail. The following table presents cumulative items not recognized as a component of net periodic benefits expense as of December 31, 2016 , items recognized as a component of net periodic benefits expense in 2017 , additional items deferred during 2017 and cumulative items not recognized as a component of net periodic benefits expense as of December 31, 2016 . The items not recognized as a component of net periodic benefits expense have been recorded on our consolidated balance sheets in accumulated other comprehensive loss: As of and for the Years Ended December 31, 2016 Recognition Deferrals Net 2017 (Dollars in millions) Accumulated other comprehensive loss: Pension plans: Net actuarial (loss) gain $ (3,148 ) 205 51 256 (2,892 ) Prior service benefit (cost) 62 (8 ) — (8 ) 54 Deferred income tax benefit (expense) 1,191 (72 ) (12 ) (84 ) 1,107 Total pension plans (1,895 ) 125 39 164 (1,731 ) Post-retirement benefit plans: Net actuarial (loss) gain (137 ) — (113 ) (113 ) (250 ) Prior service (cost) benefit (127 ) 20 — 20 (107 ) Deferred income tax benefit (expense) 102 (7 ) 27 20 122 Total post-retirement benefit plans (162 ) 13 (86 ) (73 ) (235 ) Total accumulated other comprehensive loss $ (2,057 ) 138 (47 ) 91 (1,966 )

Share-based Compensation (Table

Share-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock option awards activity	The following table summarizes activity involving stock option awards for the year ended December 31, 2018 : Number of Options Weighted- Average Exercise Price (in thousands) Outstanding and Exercisable at December 31, 2017 1,022 $ 27.41 Exercised (178 ) 22.49 Forfeited/Expired (301 ) 30.25 Outstanding and Exercisable at December 31, 2018 543 27.46
Restricted stock and restricted stock unit awards activity	The following table summarizes activity involving restricted stock and restricted stock unit awards for the year ended December 31, 2018 : Number of Shares Weighted- Average Grant Date Fair Value (in thousands) Non-vested at December 31, 2017 19,774 $ 21.90 Granted (1) 9,657 17.02 Vested (9,275 ) 20.87 Forfeited (3,097 ) 22.12 Non-vested at December 31, 2018 17,059 19.65 _____________________________________________________________________________ (1) Shares granted whose related performance conditions were not finalized at December 31, 2018, were excluded from this figure.

(Loss) Earnings Per Common Sh_2

(Loss) Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of basic and diluted earnings per common share	Basic and diluted (loss) earnings per common share for the years ended December 31, 2018 , 2017 and 2016 were calculated as follows: Years Ended December 31, 2018 2017 2016 (Dollars in millions, except per share amounts, shares in thousands) Loss income (Numerator): Net (loss) income $ (1,733 ) 1,389 626 Net (loss) income applicable to common stock for computing basic earnings per common share (1,733 ) 1,389 626 Net (loss) income as adjusted for purposes of computing diluted earnings per common share $ (1,733 ) 1,389 626 Shares (Denominator): Weighted average number of shares: Outstanding during period 1,078,409 635,576 545,946 Non-vested restricted stock (12,543 ) (7,768 ) (6,397 ) Weighted average shares outstanding for computing basic earnings per common share 1,065,866 627,808 539,549 Incremental common shares attributable to dilutive securities: Shares issuable under convertible securities — 10 10 Shares issuable under incentive compensation plans — 875 1,120 Number of shares as adjusted for purposes of computing diluted (loss) earnings per common share 1,065,866 628,693 540,679 Basic (loss) earnings per common share $ (1.63 ) 2.21 1.16 Diluted (loss) earnings per common share (1) $ (1.63 ) 2.21 1.16 _______________________________________________________________________________ (1) For the year ended December 31, 2018, we excluded from the calculation of diluted loss per share 4.6 million shares potentially issuable under incentive compensation plans or convertible securities, as their effect, if included, would have been anti-dilutive.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of the three input levels in the hierarchy of fair value measurements	The three input levels in the hierarchy of fair value measurements are defined by the FASB generally as follows: Input Level Description of Input Level 1 Observable inputs such as quoted market prices in active markets. Level 2 Inputs other than quoted prices in active markets that are either directly or indirectly observable. Level 3 Unobservable inputs in which little or no market data exists.
Schedule of carrying amounts and estimated fair values of long-term debt, excluding capital lease obligations, and input levels to determine fair values	The following table presents the carrying amounts and estimated fair values of our long-term debt, excluding capital lease and other obligations, as well as the input level used to determine the fair values indicated below: As of December 31, 2018 As of December 31, 2017 Input Level Carrying Amount Fair Value Carrying Amount Fair Value (Dollars in millions) Liabilities-Long-term debt, excluding capital lease and other obligations 2 $ 35,260 32,915 36,835 36,402

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of components of provision for income tax	Years Ended December 31, 2018 2017 2016 (Dollars in millions) Income tax expense (benefit) was as follows: Federal Current $ (576 ) 82 335 Deferred 734 (988 ) 5 State Current (22 ) 21 27 Deferred 52 16 8 Foreign Current 36 22 26 Deferred (54 ) (2 ) (7 ) Total income tax expense (benefit) $ 170 (849 ) 394 Years Ended December 31, 2018 2017 2016 (Dollars in millions) Income tax (benefit) expense was allocated as follows: Income tax (benefit) expense in the consolidated statements of operations: Attributable to income $ 170 (849 ) 394 Stockholders' equity: Compensation expense for tax purposes in excess of amounts recognized for financial reporting purposes — — (2 ) Tax effect of the change in accumulated other comprehensive loss (2 ) 81 (109 )
Schedule of reconciliation of the statutory federal income tax rate to effective income tax rate	The following is a reconciliation from the statutory federal income tax rate to our effective income tax rate: Years Ended December 31, 2018 2017 2016 (Percentage of pre-tax income) Statutory federal income tax rate 21.0 % 35.0 % 35.0 % State income taxes, net of federal income tax benefit (1.5 )% 3.9 % 2.3 % Impairment of goodwill (36.6 )% — % — % Change in liability for unrecognized tax position 1.3 % 1.0 % 0.2 % Tax reform (5.9 )% (209.8 )% — % Net foreign income taxes 1.8 % (0.7 )% 0.1 % Foreign dividend paid to a domestic parent company — % 0.2 % 1.8 % Research and development credits 0.9 % (1.4 )% (0.6 )% Tax impact on sale of data centers and colocation business — % 5.0 % — % Tax benefit of net operating loss carryback 9.1 % — % — % Level 3 acquisition transaction costs — % 6.0 % — % Other, net (1.0 )% 3.6 % (0.2 )% Effective income tax rate (10.9 )% (157.2 )% 38.6 %
Schedule of components of deferred tax assets and deferred tax liabilities	The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and deferred tax liabilities were as follows: As of December 31, 2018 2017 (Dollars in millions) Deferred tax assets Post-retirement and pension benefit costs $ 1,111 1,321 Net operating loss carryforwards 3,445 3,951 Other employee benefits 162 112 Other 553 714 Gross deferred tax assets 5,271 6,098 Less valuation allowance (1,331 ) (1,341 ) Net deferred tax assets 3,940 4,757 Deferred tax liabilities Property, plant and equipment, primarily due to depreciation differences (3,011 ) (2,935 ) Goodwill and other intangible assets (3,303 ) (3,785 ) Other (23 ) (16 ) Gross deferred tax liabilities (6,337 ) (6,736 ) Net deferred tax liability $ (2,397 ) (1,979 )
Summary of NOLs	If unused, the NOLs will expire between 2022 and 2037 . The U.S. federal net operating loss carryforwards expire as follows: Expiring Amount December 31, (Dollars in millions) 2022 $ 1,043 2023 1,440 2024 1,402 2025 1,042 2026 1,525 2027 375 2028 637 2029 645 2030 671 2031 732 2032 348 2033 238 2037 2,715 NOLs per return 12,813 Uncertain tax positions (5,526 ) Financial NOLs $ 7,287
Summary of the reconciliation of the change in gross unrecognized tax benefits	A reconciliation of the change in our gross unrecognized tax benefits (excluding both interest and any related federal benefit) from January 1 to December 31 for 2018 and 2017 is as follows: 2018 2017 (Dollars in millions) Unrecognized tax benefits at beginning of year $ 40 16 Assumed in the acquisition of Level 3 — 18 Tax position of prior periods netted against deferred tax assets 1,338 2 Increase in tax positions taken in the current year 4 1 Increase in tax positions taken in the prior year 211 3 Decrease due to payments/settlements (1 ) — Decrease from the lapse of statute of limitations (2 ) — Decrease due to the reversal of tax positions taken in a prior year (3 ) — Unrecognized tax benefits at end of year $ 1,587 40

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of segment information	The following table summarizes our segment results for 2018 , 2017 and 2016 based on the segment categorization we were operating under at December 31, 2018 . Years Ended December 31, 2018 2017 2016 (Dollars in millions) Total segment revenue $ 22,720 16,924 16,766 Total segment expenses 12,269 9,390 9,081 Total segment adjusted EBITDA $ 10,451 7,534 7,685 Total margin percentage 46 % 45 % 46 % Business segment: Revenue $ 17,349 11,220 10,704 Expenses 10,076 6,847 6,391 Adjusted EBITDA $ 7,273 4,373 4,313 Margin percentage 42 % 39 % 40 % Consumer segment: Revenue $ 5,371 5,704 6,062 Expenses 2,193 2,543 2,690 Adjusted EBITDA $ 3,178 3,161 3,372 Margin percentage 59 % 55 % 56 %
Schedule of operating revenues by products and services	Our operating revenue for our products and services are presented as follows for the years ended December 31, 2018 , 2017 and 2016 : Years Ended December 31, 2018 2017 2016 (Dollars in millions) Business segment IP and Data Services (1) $ 6,971 3,682 2,957 Transport and Infrastructure (2) 5,356 3,569 3,807 Voice and Collaboration (3) 4,401 3,317 3,299 IT and Managed Services (4) 621 652 641 Total business segment revenue 17,349 11,220 10,704 Consumer segment IP and Data Services (5) 308 401 461 Transport and Infrastructure (6) 2,892 2,776 2,776 Voice and Collaboration (3) 2,171 2,527 2,825 Total consumer segment revenue 5,371 5,704 6,062 Non-segment revenue Regulatory Revenue (7) 723 732 704 Total non-segment revenue 723 732 704 Total revenue $ 23,443 17,656 17,470 ______________________________________________________________________ (1) Includes primarily VPN data network, Ethernet, IP and ancillary revenue. (2) Includes primarily broadband, private line (including business data services), colocation and data centers, wavelength and ancillary revenue. (3) Includes local, long-distance and other ancillary revenue. (4) Includes IT services and managed services revenue. (5) Includes retail video revenue (including our facilities-based video revenue). (6) Includes primarily broadband and equipment sales and professional services revenue. (7) Includes CAF Phase I, CAF Phase II, federal and state USF support revenue, sublease rental income and failed-sale leaseback income.
Schedule of reconciliation from segment income to consolidated net income	The following table reconciles total segment adjusted EBITDA to net (loss) income for the years ended December 31, 2018 , 2017 and 2016 : Years Ended December 31, 2018 2017 2016 (Dollars in millions) Total segment adjusted EBITDA $ 10,451 7,534 7,685 Regulatory Revenue 723 732 704 Depreciation and amortization (5,120 ) (3,936 ) (3,916 ) Impairment of goodwill (2,726 ) — — Other operating expenses (2,758 ) (2,321 ) (2,140 ) Total other expenses, net (2,133 ) (1,469 ) (1,313 ) Income (loss) before income tax expense (1,563 ) 540 1,020 Income tax (expense) benefit (170 ) 849 (394 ) Net (loss) income $ (1,733 ) 1,389 626

Quarterly Financial Data (Una_2

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly financial information	First Quarter Second Quarter Third Quarter Fourth Quarter Total (Dollars in millions, except per share amounts) 2018 Operating revenue $ 5,945 5,902 5,818 5,778 23,443 Operating income (loss) 750 767 894 (1,841 ) 570 Net income (loss) 115 292 272 (2,412 ) (1,733 ) Basic earnings (loss) per common share 0.11 0.27 0.25 (2.26 ) (1.63 ) Diluted earnings (loss) per common share 0.11 0.27 0.25 (2.26 ) (1.63 ) 2017 Operating revenue $ 4,209 4,090 4,034 5,323 17,656 Operating income 631 367 487 524 2,009 Net income 163 17 92 1,117 1,389 Basic earnings per common share 0.30 0.03 0.17 1.26 2.21 Diluted earnings per common share 0.30 0.03 0.17 1.26 2.21

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of capital lease activity	The tables below summarize our capital lease activity: Years Ended December 31, 2018 2017 2016 (Dollars in millions) Assets acquired through capital leases $ 25 35 45 Depreciation expense 51 50 70 Cash payments towards capital leases 48 48 58 As of December 31, 2018 2017 (Dollars in millions) Assets included in property, plant and equipment $ 427 420 Accumulated depreciation 180 154
Schedule of future annual minimum payments under capital lease arrangements	The future annual minimum payments under capital lease arrangements as of December 31, 2018 were as follows: Future Minimum Payments (Dollars in millions) Capital lease obligations: 2019 $ 51 2020 36 2021 23 2022 21 2023 20 2024 and thereafter 183 Total minimum payments 334 Less: amount representing interest and executory costs (100 ) Present value of minimum payments 234 Less: current portion (38 ) Long-term portion $ 196
Schedule of future rental commitments for operating leases	At December 31, 2018 , our future rental commitments for Right-of-Way agreements and operating leases were as follows: Right-of-Way Agreements Operating Leases Total (Dollars in millions) 2019 157 675 832 2020 134 443 577 2021 112 355 467 2022 120 279 399 2023 115 241 356 2024 and thereafter 755 969 1,724 Total future minimum payments (1) 1,393 2,962 4,355 _______________________________________________________________________________ (1) Minimum payments have not been reduced by minimum sublease rentals of $101 million due in the future under non-cancelable subleases.

Other Financial Information (Ta

Other Financial Information (Tables)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of components of other current assets	The following table presents details of other current assets in our consolidated balance sheets: As of December 31, 2018 2017 (Dollars in millions) Prepaid expenses $ 307 294 Income tax receivable 82 258 Materials, supplies and inventory 120 128 Contract assets 134 — Contract acquisition costs and deferred activation and installation charges 167 128 Other 108 133 Total other current assets $ 918 941
Schedule of current liabilities including accounts payable and other current liabiities	Current liabilities reflected in our consolidated balance sheets include accounts payable and other current liabilities as follows: As of December 31, 2018 2017 (Dollars in millions) Accounts payable $ 1,933 1,555 Other current liabilities: Accrued rent $ 45 34 Legal contingencies 30 45 Other 282 265 Total other current liabilities $ 357 344

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Summary of the entity's accumulated other comprehensive income (loss) by component	The table below summarizes changes in accumulated other comprehensive loss recorded on our consolidated balance sheet by component for the year ended December 31, 2018 : Pension Plans Post-Retirement Benefit Plans Foreign Currency Translation Adjustment and Other Total (Dollars in millions) Balance at December 31, 2017 $ (1,731 ) (235 ) (29 ) (1,995 ) Other comprehensive loss before reclassifications (195 ) 194 (201 ) (202 ) Amounts reclassified from accumulated other comprehensive loss 128 15 — 143 Net current-period other comprehensive (loss) income (67 ) 209 (201 ) (59 ) Cumulative effect of adoption of ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (375 ) (32 ) — (407 ) Balance at December 31, 2018 $ (2,173 ) (58 ) (230 ) (2,461 ) The table below summarizes changes in accumulated other comprehensive loss recorded on our consolidated balance sheet by component for the year ended December 31, 2017 : Pension Plans Post-Retirement Benefit Plans Foreign Currency Translation Adjustment and Other Total (Dollars in millions) Balance at December 31, 2016 $ (1,895 ) (162 ) (60 ) (2,117 ) Other comprehensive income (loss) before reclassifications 39 (86 ) 31 (16 ) Amounts reclassified from accumulated other comprehensive loss 125 13 — 138 Net current-period other comprehensive income (loss) 164 (73 ) 31 122 Balance at December 31, 2017 $ (1,731 ) (235 ) (29 ) (1,995 )
Schedule of reclassifications out of accumulated other comprehensive income (loss) by component	The table below presents further information about our reclassifications out of accumulated other comprehensive loss by component for the year ended December 31, 2017 : Year Ended December 31, 2017 Decrease (Increase) in Net Income Affected Line Item in Consolidated Statement of Operations (Dollars in millions) Amortization of pension & post-retirement plans (1) Net actuarial loss $ 205 Other income, net Prior service cost 12 Other income, net Total before tax 217 Income tax benefit (79 ) Income tax expense (benefit) Net of tax $ 138 ________________________________________________________________________ (1) See Note 10—Employee Benefits for additional information on our net periodic benefit (expense) income related to our pension and post-retirement plans. The table below presents further information about our reclassifications out of accumulated other comprehensive loss by component for the year ended December 31, 2018 : Year Ended December 31, 2018 Decrease (Increase) in Net Loss Affected Line Item in Consolidated Statement of Operations (Dollars in millions) Amortization of pension & post-retirement plans (1) Net actuarial loss $ 178 Other income, net Prior service cost 12 Other income, net Total before tax 190 Income tax benefit (47 ) Income tax expense (benefit) Net of tax $ 143 ________________________________________________________________________ (1) See Note 10—Employee Benefits for additional information on our net periodic benefit (expense) income related to our pension and post-retirement plans.

Dividends (Tables)

Dividends (Tables)	12 Months Ended
	Dec. 31, 2018
Dividends, Common Stock [Abstract]
Schedule of dividends declared	Our Board of Directors declared the following dividends payable in 2018 and 2017 : Date Declared Record Date Dividend Per Share Total Amount Payment Date (in millions) November 14, 2018 11/26/2018 $ 0.540 $ 586 12/7/2018 August 21, 2018 8/31/2018 0.540 584 9/14/2018 May 23, 2018 6/4/2018 0.540 588 6/15/2018 February 21, 2018 3/5/2018 0.540 586 3/16/2018 November 14, 2017 11/27/2017 0.540 577 12/11/2017 August 22, 2017 9/5/2017 0.540 296 9/15/2017 May 24, 2017 6/5/2017 0.540 297 6/16/2017 February 21, 2017 3/3/2017 0.540 295 3/17/2017

Background and Summary of Sig_4

Background and Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, shares in Millions, $ in Millions	Jan. 01, 2019USD ($)	Oct. 31, 2018reporting_unit	Oct. 31, 2017reporting_unit	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)reporting_unit$ / sharesshares	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Finite-Lived Intangible Assets [Line Items]
Advertising expense					$ 98	$ 218	$ 216
Accounts receivable, past due threshold					30 days
Reclassification from AOCI to retained earnings, tax effect				$ 407
Number of reporting units | reporting_unit		5	3		5
Goodwill impairment					$ 2,726	0	0
Capitalized labor and related costs					$ 569	559	524
Minimum
Finite-Lived Intangible Assets [Line Items]
Contract term					1 year
Customer relationship period for revenue recognition					10 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Contract term					7 years
Customer relationship period for revenue recognition					20 years
Customer relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life					7 years
Customer relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life					15 years
Capitalized software
Finite-Lived Intangible Assets [Line Items]
Estimated useful life					7 years
Integrated billing and customer care system
Finite-Lived Intangible Assets [Line Items]
Estimated useful life					20 years
Finite-lived intangible assets, gross					$ 237
Other intangible assets | Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life					4 years
Other intangible assets | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life					20 years
Common Stock
Finite-Lived Intangible Assets [Line Items]
Unissued shares of CenturyLink common stock | shares					4
Nonredeemable Preferred Stock
Finite-Lived Intangible Assets [Line Items]
Redemption price (in dollars per share) | $ / shares					$ 25
Stock compensation plan | Common Stock
Finite-Lived Intangible Assets [Line Items]
Unissued shares of CenturyLink common stock | shares					30
Accounting Standards Update 2016-02 | Subsequent event
Finite-Lived Intangible Assets [Line Items]
Sale leaseback transaction, deferred gain, gross	$ 115
Term of recognition	3 years
Accounting Standards Update 2016-02 | Minimum | Subsequent event
Finite-Lived Intangible Assets [Line Items]
Right-of-use asset	$ 1,900
Operating lease, liability	1,900
Accounting Standards Update 2016-02 | Maximum | Subsequent event
Finite-Lived Intangible Assets [Line Items]
Right-of-use asset	2,200
Operating lease, liability	$ 2,200
Retained Earnings | Accounting Standards Update 2014-09
Finite-Lived Intangible Assets [Line Items]
Cumulative effect of adoption					$ 338	0	0
Cumulative net effect of adoption of ASU, tax					$ 119	$ 0	$ 0
Consumer Customers | Weighted Average
Finite-Lived Intangible Assets [Line Items]
Length of customer life					30 months
Business Customer
Finite-Lived Intangible Assets [Line Items]
Length of customer life					49 months
Business Customer | Minimum
Finite-Lived Intangible Assets [Line Items]
Length of customer life					12 months
Business Customer | Maximum
Finite-Lived Intangible Assets [Line Items]
Length of customer life					60 months

Background and Summary of Sig_5

Background and Summary of Significant Accounting Policies - Effect of 2016-02 (Details) - USD ($) $ in Millions	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment		$ (26,408)	$ (26,852)
Long-term debt		(35,409)	(37,283)
Deferred income taxes		(2,527)	(2,413)
Stockholder's equity		$ (19,828)	$ (23,491)	$ (13,399)
Subsequent event | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment	$ (409)
Deferred rent	(3)
Long-term debt	(558)
Deferred income taxes	37
Stockholder's equity	$ 115

Acquisition of Level 3 - Additi

Acquisition of Level 3 - Additional Information (Details) $ / shares in Units, shares in Millions	Nov. 01, 2017USD ($)citydark_fiber$ / sharesshares	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2018USD ($)	Oct. 31, 2018USD ($)	Oct. 31, 2017$ / sharesshares	Dec. 31, 2016USD ($)
Business Acquisition [Line Items]
Goodwill		$ 28,031,000,000	$ 30,475,000,000	$ 28,031,000,000			$ 19,650,000,000
Level 3 Parent, LLC
Business Acquisition [Line Items]
Price per share of stock in business acquisition (in dollars per share) | $ / shares	$ 26.50
Stock conversion ratio	1.4286
Business acquisition total consideration	$ 19,600,000,000
Equity interests issued or issuable (in shares) | shares	517.3
Price of share of common stock (in dollars per share) | $ / shares						$ 18.99
Shares outstanding (in shares) | shares						362.1
Consideration transferred, dissenting shares	$ 60,000,000
Long-term debt	$ 10,600,000,000		10,888,000,000		$ 10,888,000,000
Dark fiber divested | dark_fiber	24
Number of cities | city	30
Note payable - related party	$ 1,825,000,000
Goodwill			10,837,000,000		$ 11,177,000,000
Acquisition-related expenses		393,000,000	271,000,000	716,000,000
Transaction-related expenses		$ 2,000,000	$ 174,000,000	$ 2,000,000
Level 3 Parent, LLC | Medium-term Notes | Term Loan
Business Acquisition [Line Items]
Debt instrument, face amount	7,945,000,000
Level 3 Parent, LLC | Revolving Credit Facility | 2017 Revolving Credit Facility
Business Acquisition [Line Items]
Debt instrument, face amount	$ 400,000,000
Level 3 Parent, LLC | Restricted Stock
Business Acquisition [Line Items]
Price per share of stock in business acquisition (in dollars per share) | $ / shares	$ 26.50
Stock conversion ratio	1.4286
Level 3 Parent, LLC | Restricted Stock Units (RSUs)
Business Acquisition [Line Items]
Stock conversion ratio	2.8386
Business acquisition total consideration	$ 136,000,000
Consideration transferred, settlement of shares	1,000,000
Level 3 Parent, LLC | Level 3 Communications, Inc.
Business Acquisition [Line Items]
Transaction-related expenses	$ 47,000,000
Level 3 Parent, LLC | Level 3 Communications, Inc.
Business Acquisition [Line Items]
Ownership percentage by parent	51.00%
Level 3 Parent, LLC | Level 3 Communications, Inc. | Level 3 Shareholders
Business Acquisition [Line Items]
Ownership percentage by noncontrolling owners	49.00%

Sale of Data Centers and Colo_3

Sale of Data Centers and Colocation Business - Additional Information (Details) - USD ($) $ in Millions	May 01, 2017	Jun. 30, 2017	Mar. 31, 2017	May 01, 2017	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 01, 2017
Cyxtera Technologies
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Due to affiliate, current						$ 3
Current amount due from affiliate					$ 49	10	$ 49
Payments for rent						132
Sale-leaseback transaction rent expense					$ 80
Cyxtera Technologies
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on asset leaseback, failed-sale-leaseback transaction		$ (119)				(102)
Sale and leaseback transaction loss, net						(82)
SIS Holdings, LP
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncontrolling interest in limited partnerships	$ 150			$ 150		150			$ 150
Colocation Business and Data Centers
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from sales of colocation business and data centers	$ 1,800
Tax effect of gain (loss) from disposal of discontinued operation							$ 47	$ 18	$ 65
Depreciation and amortization			$ 50	$ 67
Colocation Business and Data Centers | Cyxtera Technologies | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal group, gain (loss) on disposal						$ 20

Acquisition of Level 3 - Aggreg

Acquisition of Level 3 - Aggregate Consideration (Details) - USD ($) $ in Millions	Nov. 01, 2017	Sep. 30, 2018	Dec. 31, 2018	Oct. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill			$ 28,031		$ 30,475	$ 19,650
Purchase Price Adjustments
Acquired finite-lived intangible assets, weighted average useful life			11 years
Customer relationships
Purchase Price Adjustments
Acquired finite-lived intangible assets, weighted average useful life			11 years
Level 3 Parent, LLC
Business Acquisition [Line Items]
Cash, accounts receivable and other current assets				$ 3,291	3,317
Property, plant and equipment				9,468	9,311
Other noncurrent assets				998	782
Current liabilities, excluding current maturities of long-term debt				(1,493)	(1,461)
Current maturities of long-term debt				(7)	(7)
Long-term debt	$ (10,600)			(10,888)	(10,888)
Deferred revenue and other liabilities				(1,743)	(1,629)
Goodwill				11,177	10,837
Total estimated aggregate consideration				19,612	19,617
Purchase Price Adjustments
Cash, accounts receivable and other current assets		$ (26)
Property, plant and equipment		157
Other noncurrent assets		216
Current liabilities, excluding current maturities of long-term debt		(32)
Current maturities of long-term debt		0
Long-term debt		0
Deferred revenue and other liabilities		(114)
Goodwill		340
Total estimated aggregate consideration		(5)
Accounts receivable, contractual value	$ 884			884
Acquired finite-lived intangible assets, weighted average useful life	12 years
Level 3 Parent, LLC | Customer relationships
Business Acquisition [Line Items]
Identifiable intangible assets				8,431	8,964
Purchase Price Adjustments
Identifiable intangible assets		(533)
Level 3 Parent, LLC | Other intangible assets
Business Acquisition [Line Items]
Identifiable intangible assets				$ 378	$ 391
Purchase Price Adjustments
Identifiable intangible assets		$ (13)

Sale of Data Centers and Colo_4

Sale of Data Centers and Colocation Business - Assets Sold to and Liabilities Assumed (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	May 01, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Less assets not removed as a result of the failed-sale-leaseback	$ (53,267)	$ (51,204)
Assets held for sale	$ 12	$ 140
Colocation Business and Data Centers | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill			$ 1,142
Property, plant and equipment			1,051
Other intangible assets			249
Other assets			66
Less assets not removed as a result of the failed-sale-leaseback			(526)
Assets held for sale			1,982
Capital lease obligations			294
Other liabilities			274
Less imputed financing obligations from the failed-sale-leaseback			(628)
Total net imputed liabilities recognized			$ (60)

Acquisition of Level 3 - Acquis

Acquisition of Level 3 - Acquisition Related Expenses (Details) - Level 3 Parent, LLC - USD ($) $ in Millions	12 Months Ended		14 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018
Business Acquisition [Line Items]
Transaction-related expenses	$ 2	$ 174	$ 2
Integration-related expenses	391	97
Total acquisition-related expenses	$ 393	$ 271	$ 716

Sale of Data Centers and Colo_5

Sale of Data Centers and Colocation Business - Effects of Failed-sale-Leaseback (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Sale Leaseback Transaction [Line Items]
Operating revenue	$ 5,778	$ 5,818	$ 5,902	$ 5,945	$ 5,323	$ 4,034	$ 4,090	$ 4,209	$ 23,443	$ 17,656	$ 17,470
Decrease in cost of sales									(10,862)	(8,203)	(7,774)
Increase in loss on sale of business included in selling, general and administrative expense									(4,165)	(3,508)	(3,447)
Increase in depreciation expense (ongoing)									(5,120)	(3,936)	(3,916)
Increase in interest expense									(2,177)	(1,481)	(1,318)
Decrease in income tax expense									(170)	849	(394)
NET (LOSS) INCOME	$ (2,412)	$ 272	$ 292	$ 115	$ 1,117	$ 92	17	$ 163	(1,733)	1,389	$ 626
Cyxtera Technologies
Sale Leaseback Transaction [Line Items]
Operating revenue									74	49
Decrease in cost of sales									22	15
Increase in loss on sale of business included in selling, general and administrative expense									0	(102)
Increase in depreciation expense (one-time)							$ (44)		0	(44)
Increase in depreciation expense (ongoing)									(69)	(47)
Increase in interest expense									(55)	(39)
Decrease in income tax expense									7	65
NET (LOSS) INCOME									$ (21)	$ (103)

Goodwill, Customer Relationsh_3

Goodwill, Customer Relationships and Other Intangible Assets - Schedule of Goodwill and Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 28,031	$ 30,475	$ 19,650
Finite-lived intangible assets, net	8,911	10,876
Indefinite-life intangible assets	269	269
Other intangible assets, net	1,868	1,897
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	8,911	10,876
Accumulated amortization	8,492	7,096
Capitalized software
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	1,468	1,469
Accumulated amortization	2,616	2,294
Tradenames and patents
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	131	159
Accumulated amortization	$ 61	$ 31

Goodwill, Customer Relationsh_4

Goodwill, Customer Relationships and Other Intangible Assets - Additional Information (Details) $ in Millions	Oct. 31, 2018reporting_unit	Oct. 31, 2017reporting_unit	Dec. 31, 2018USD ($)reporting_unit	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net			$ 19,100
Acquired finite-lived intangible assets, weighted average useful life			11 years
Amortization of intangible assets			$ 1,800	$ 1,200	$ 1,200
Intangible assets, gross			50,000
Control premium, percent	0.10%
Goodwill impairment			$ 2,726	0	0
Number of reporting units | reporting_unit	5	3	5
Goodwill			$ 28,031	30,475	19,650
Medium and Small Business
Finite-Lived Intangible Assets [Line Items]
Goodwill, impairment percent	2.00%
Enterprise
Finite-Lived Intangible Assets [Line Items]
Goodwill, impairment percent	11.00%
International and Global Accounts
Finite-Lived Intangible Assets [Line Items]
Goodwill, impairment percent	30.00%
Wholesale and Indirect
Finite-Lived Intangible Assets [Line Items]
Goodwill, impairment percent	5.00%
Business
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment			0
Goodwill			20,447	$ 20,197	$ 9,372
Business | Medium and Small Business
Finite-Lived Intangible Assets [Line Items]
Goodwill			5,193
Business | Enterprise
Finite-Lived Intangible Assets [Line Items]
Goodwill			5,222
Business | International and Global Accounts
Finite-Lived Intangible Assets [Line Items]
Goodwill			3,596
Business | Wholesale and Indirect
Finite-Lived Intangible Assets [Line Items]
Goodwill			$ 6,436
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life			11 years
Capitalized software
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life			3 years
Tradenames and patents
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life			4 years

Goodwill, Customer Relationsh_5

Goodwill, Customer Relationships and Other Intangible Assets - Future Amortization Expense (Details) $ in Millions	Dec. 31, 2018USD ($)
Expected amortization expense
2019	$ 1,691
2020	1,589
2021	1,156
2022	985
2023	$ 893

Goodwill, Customer Relationsh_6

Goodwill, Customer Relationships and Other Intangible Assets - Goodwill Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill Activity
Goodwill at the beginning of the period	$ 30,475	$ 19,650
Goodwill acquired during period	282	10,825
Goodwill impairment	(2,726)	0	$ 0
Goodwill at the end of the period	28,031	30,475	19,650
Foreign currency translation gain (loss)	(58)
Level 3 Parent, LLC
Goodwill Activity
Goodwill at the beginning of the period	10,837
Goodwill at the end of the period		10,837
Business
Goodwill Activity
Goodwill at the beginning of the period	20,197	9,372
Goodwill acquired during period	250	10,825
Goodwill impairment	0
Goodwill at the end of the period	20,447	20,197	9,372
Goodwill accumulated impairment loss	1,100
Consumer
Goodwill Activity
Goodwill at the beginning of the period	10,278	10,278
Goodwill acquired during period	32	0
Goodwill impairment	(2,726)
Goodwill at the end of the period	7,584	$ 10,278	$ 10,278
Consumer | Level 3 Parent, LLC
Goodwill Activity
Goodwill acquired during period	$ 32

Goodwill, Customer Relationsh_7

Goodwill, Customer Relationships and Other Intangible Assets - Schedule of Goodwill by Segment (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 28,031	$ 30,475	$ 19,650
Business
Business Acquisition [Line Items]
Goodwill	20,447	20,197	9,372
Business | Medium and Small Business
Business Acquisition [Line Items]
Goodwill	5,193
Business | Enterprise
Business Acquisition [Line Items]
Goodwill	5,222
Business | International and Global Accounts
Business Acquisition [Line Items]
Goodwill	3,596
Business | Wholesale and Indirect
Business Acquisition [Line Items]
Goodwill	6,436
Consumer
Business Acquisition [Line Items]
Goodwill	$ 7,584	$ 10,278	$ 10,278

Revenue Recognition - Reported

Revenue Recognition - Reported Results Under ASC 606 (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating revenue	$ 5,778	$ 5,818	$ 5,902	$ 5,945	$ 5,323	$ 4,034	$ 4,090	$ 4,209	$ 23,443	$ 17,656	$ 17,470
Cost of services and products (exclusive of depreciation and amortization)									10,862	8,203	7,774
Selling, general and administrative									4,165	3,508	3,447
Interest expense									2,177	1,481	1,318
Attributable to income									170	(849)	394
Net (loss) income	$ (2,412)	$ 272	$ 292	$ 115	$ 1,117	$ 92	$ 17	$ 163	$ (1,733)	$ 1,389	$ 626
BASIC AND DILUTED LOSS PER COMMON SHARE
BASIC (in dollars per share)	$ (2.26)	$ 0.25	$ 0.27	$ 0.11	$ 1.26	$ 0.17	$ 0.03	$ 0.30	$ (1.63)	$ 2.21	$ 1.16
DILUTED (in dollars per share)	$ (2.26)	$ 0.25	$ 0.27	$ 0.11	$ 1.26	$ 0.17	$ 0.03	$ 0.30	$ (1.63)	$ 2.21	$ 1.16
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING
BASIC (in shares)									1,065,866	627,808	539,549
DILUTED (in shares)									1,065,866	628,693	540,679
Other current assets	$ 918				$ 941				$ 918	$ 941
Other long-term assets, net	1,060								1,060
Deferred revenue	2,375								2,375
Deferred income taxes, net	2,395								2,395
Other long-term liabilities	1,099								1,099
Accumulated deficit	(1,643)				$ 1,103				(1,643)	$ 1,103
Impact of ASC 606 | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating revenue									39
Cost of services and products (exclusive of depreciation and amortization)									22
Selling, general and administrative									71
Interest expense									(9)
Attributable to income									(12)
Net (loss) income									$ (33)
BASIC AND DILUTED LOSS PER COMMON SHARE
BASIC (in dollars per share)									$ (0.03)
DILUTED (in dollars per share)									$ (0.03)
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING
BASIC (in shares)									0
DILUTED (in shares)									0
Other current assets	(172)								$ (172)
Other long-term assets, net	(112)								(112)
Deferred revenue	71								71
Deferred income taxes, net	(131)								(131)
Other long-term liabilities	147								147
Accumulated deficit	(371)								(371)
ASC 605 Historical Adjusted Balances
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating revenue									23,482
Cost of services and products (exclusive of depreciation and amortization)									10,884
Selling, general and administrative									4,236
Interest expense									2,168
Attributable to income									158
Net (loss) income									$ (1,766)
BASIC AND DILUTED LOSS PER COMMON SHARE
BASIC (in dollars per share)									$ (1.66)
DILUTED (in dollars per share)									$ (1.66)
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING
BASIC (in shares)									1,065,866
DILUTED (in shares)									1,065,866
Other current assets	746								$ 746
Other long-term assets, net	948								948
Deferred revenue	2,446								2,446
Deferred income taxes, net	2,264								2,264
Other long-term liabilities	1,246								1,246
Accumulated deficit	$ (2,014)								$ (2,014)

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue	$ 5,778	$ 5,818	$ 5,902	$ 5,945	$ 5,323	$ 4,034	$ 4,090	$ 4,209	$ 23,443	$ 17,656	$ 17,470
Adjustments									(1,538)
Total Revenue from Contracts with Customers									21,905
Transferred at Point in Time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue from Contracts with Customers									230
Transferred over Time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue from Contracts with Customers									21,675
Business
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									17,349	11,220	10,704
Consumer
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									5,371	5,704	6,062
Operating Segments | Business
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									17,349	11,220	10,704
Adjustments									(569)
Total Revenue from Contracts with Customers									16,780
Operating Segments | Consumer
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									5,371	5,704	6,062
Adjustments									(246)
Total Revenue from Contracts with Customers									5,125
Operating Segments | IP & Data Services | Business
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									6,971	3,682	2,957
Adjustments									0
Total Revenue from Contracts with Customers									6,971
Operating Segments | IP & Data Services | Consumer
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									308	401	461
Adjustments									(33)
Total Revenue from Contracts with Customers									275
Operating Segments | Transport & Infrastructure | Business
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									5,356	3,569	3,807
Adjustments									(569)
Total Revenue from Contracts with Customers									4,787
Operating Segments | Transport & Infrastructure | Consumer
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									2,892	2,776	2,776
Adjustments									(213)
Total Revenue from Contracts with Customers									2,679
Operating Segments | Voice & Collaboration | Business
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									4,401	3,317	3,299
Adjustments									0
Total Revenue from Contracts with Customers									4,401
Operating Segments | Voice & Collaboration | Consumer
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									2,171	2,527	2,825
Adjustments									0
Total Revenue from Contracts with Customers									2,171
Operating Segments | IT & Managed Services | Business
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									621	652	641
Adjustments									0
Total Revenue from Contracts with Customers									621
Corporate, Non-Segment
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									723	732	704
Adjustments									(723)
Total Revenue from Contracts with Customers									0
Corporate, Non-Segment | Regulatory Revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									723	$ 732	$ 704
Adjustments									(723)
Total Revenue from Contracts with Customers									$ 0

Revenue Recognition - Contract

Revenue Recognition - Contract with Customer, Asset and Liability (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jan. 01, 2018
Revenue from Contract with Customer [Abstract]
Customer receivables	$ 2,346	$ 2,504
Contract liabilities	860	904
Contract assets	140	145
Accounts receivable, gross	2,500	2,700
Allowance for doubtful accounts	$ 132	$ 155

Revenue Recognition - Revenue R

Revenue Recognition - Revenue Recognized (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Amounts included in contract liability at the beginning of the period (January 1, 2018)	$ 295
Performance obligations satisfied in previous periods	$ 0

Revenue Recognition - Remaining

Revenue Recognition - Remaining Performance Obligation (Details) $ in Billions	Dec. 31, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Remaining performance obligation	$ 6.9
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percentage	83.00%
Remaining performance obligation, satisfaction period	3 years

Revenue Recognition - Capitaliz

Revenue Recognition - Capitalized Contract Costs (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Contract Acquisition Costs
Capitalized Contract Cost [Roll Forward]
Beginning of period balance	$ 268
Costs incurred	226
Amortization	(172)
End of period balance	322
Contract Fulfillment Costs
Capitalized Contract Cost [Roll Forward]
Beginning of period balance	133
Costs incurred	146
Amortization	(92)
End of period balance	$ 187

Revenue Recognition - Additiona

Revenue Recognition - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating revenue	$ 5,778	$ 5,818	$ 5,902	$ 5,945	$ 5,323	$ 4,034	$ 4,090	$ 4,209	$ 23,443	$ 17,656	$ 17,470
Minimum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract term									1 year
Maximum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract term									7 years
Consumer Customers | Weighted Average
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Length of customer life									30 months
Business Customer
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Length of customer life									49 months
Business Customer | Minimum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Length of customer life									12 months
Business Customer | Maximum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Length of customer life									60 months

Long-Term Debt and Credit Fac_3

Long-Term Debt and Credit Facilities - Schedule of Long Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 35,854
Capital lease and other obligations	801	$ 891
Unamortized (discounts) premiums and other, net	(8)	23
Unamortized debt issuance costs	(283)	(350)
Total long-term debt	36,061	37,726
Less current maturities	(652)	(443)
Long-term debt, excluding current maturities	35,409	37,283
Credit facility | CenturyLink, Inc. | 2017 Revolving Credit Facility
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 550	405
Weighted average interest rate	5.322%
Credit facility | CenturyLink, Inc. | 2017 Revolving Credit Facility | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage	5.13%
Credit facility | CenturyLink, Inc. | 2017 Revolving Credit Facility | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage	7.25%
Medium-term Notes | CenturyLink, Inc. | Term Loan A
Long-term Debt and Credit Facilities
Interest rate, stated percentage	5.272%
Long-term debt, gross	$ 1,622	1,575
Medium-term Notes | CenturyLink, Inc. | Term Loan A-1
Long-term Debt and Credit Facilities
Interest rate, stated percentage	5.272%
Long-term debt, gross	$ 351	370
Medium-term Notes | CenturyLink, Inc. | Term Loan B
Long-term Debt and Credit Facilities
Interest rate, stated percentage	5.272%
Long-term debt, gross	$ 5,940	$ 6,000
Medium-term Notes | Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Interest rate, stated percentage	4.754%	3.557%
Long-term debt, gross	$ 4,611	$ 4,611
Medium-term Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage	4.53%
Long-term debt, gross	$ 100	100
First mortgage bonds | Embarq Corporation
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 138	151
First mortgage bonds | Embarq Corporation | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage	7.125%
First mortgage bonds | Embarq Corporation | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage	8.375%
Senior Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 8,036	8,125
Senior Notes | CenturyLink, Inc. | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage	5.625%
Senior Notes | CenturyLink, Inc. | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage	7.65%
Senior Notes | Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 5,315	5,315
Senior Notes | Level 3 Financing, Inc. | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage	5.125%
Senior Notes | Level 3 Financing, Inc. | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage	6.125%
Senior Notes | Embarq Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage	7.995%
Long-term debt, gross	$ 1,485	1,485
Senior Notes | Level 3 Parent, LLC
Long-term Debt and Credit Facilities
Interest rate, stated percentage	5.75%
Long-term debt, gross	$ 600	600
Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 5,956	7,294
Senior Notes | Qwest Corporation | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage	6.125%
Senior Notes | Qwest Corporation | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage	7.75%
Senior Notes | Qwest Capital Funding, Inc
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 697	981
Senior Notes | Qwest Capital Funding, Inc | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage	6.875%
Senior Notes | Qwest Capital Funding, Inc | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage	7.75%
Other | Embarq Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage	9.00%
Long-term debt, gross	$ 150	$ 150

Long-Term Debt and Credit Fac_4

Long-Term Debt and Credit Facilities - Additional Information (Details)	Nov. 02, 2017	Jun. 19, 2017USD ($)lender	May 05, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2015USD ($)	Feb. 15, 2019USD ($)bank	Dec. 31, 2017USD ($)	Nov. 01, 2017USD ($)	Jul. 19, 2017	Apr. 27, 2017USD ($)
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 35,854,000,000
Coverage ratio				2
Subsequent event | Interest Rate Swap
Long-term Debt and Credit Facilities
Derivative, notional amount						$ 2,500,000,000
Number of banks involved | bank						5
Derivative, fixed interest rate						2.47926%
Debt Covenant, Period One
Long-term Debt and Credit Facilities
Leverage ratio				5
Debt Covenant, Period Two
Long-term Debt and Credit Facilities
Leverage ratio				4.75
Qwest Corporation
Long-term Debt and Credit Facilities
EBITDA ratio				2.85
Embarq Corporation
Long-term Debt and Credit Facilities
Maximum indebtedness, as a percent of tangible assets				15.00%
Medium-term Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 100,000,000			$ 100,000,000
Interest rate, stated percentage				4.53%
Medium-term Notes | Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 4,611,000,000			$ 4,611,000,000
Interest rate, stated percentage				4.754%			3.557%
Medium-term Notes | Level 3 Financing, Inc. | London Interbank Offered Rate (LIBOR)
Long-term Debt and Credit Facilities
Interest rate margin					1.00%
Medium-term Notes | Level 3 Financing, Inc. | Federal Funds Effective Swap Rate
Long-term Debt and Credit Facilities
Interest rate margin					0.50%
Medium-term Notes | Level 3 Financing, Inc. | Eurodollar
Long-term Debt and Credit Facilities
Interest rate margin					2.25%
Letter of Credit | Level 3 Parent, LLC | Letter of Credit
Long-term Debt and Credit Facilities
Letters of credit outstanding				$ 30,000,000			$ 36,000,000
Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 5,956,000,000			7,294,000,000
Senior Notes | Qwest Corporation | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				6.125%
Senior Notes | Qwest Corporation | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				7.75%
Senior Notes | Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 5,315,000,000			5,315,000,000
Senior Notes | Level 3 Financing, Inc. | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				5.125%
Senior Notes | Level 3 Financing, Inc. | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				6.125%
Senior Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 8,036,000,000			8,125,000,000
Redemption price, percentage				101.00%
Senior Notes | CenturyLink, Inc. | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				5.625%
Senior Notes | CenturyLink, Inc. | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				7.65%
Senior Notes | Level 3 Parent, LLC
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 600,000,000			600,000,000
Interest rate, stated percentage				5.75%
Senior Notes | Qwest Capital Funding, Inc
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 697,000,000			981,000,000
Senior Notes | Qwest Capital Funding, Inc | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				6.875%
Senior Notes | Qwest Capital Funding, Inc | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				7.75%
Senior Notes | Embarq Corporation
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 1,485,000,000			1,485,000,000
Interest rate, stated percentage				7.995%
New Senior Secured Credit Facilities
Long-term Debt and Credit Facilities
Long-term debt, gross		$ 10,245,000,000
2017 Revolving Credit Facility | Revolving Credit Facility | CenturyLink Escrow, LLC
Long-term Debt and Credit Facilities
Maximum borrowing capacity		$ 2,168,000,000
Lenders of credit facility | lender		18
2017 Revolving Credit Facility | Revolving Credit Facility | CenturyLink Escrow, LLC | Swingline Loan
Long-term Debt and Credit Facilities
Maximum borrowing capacity		$ 100,000,000
2017 Revolving Credit Facility | Revolving Credit Facility | CenturyLink Escrow, LLC | Letter of Credit
Long-term Debt and Credit Facilities
Maximum borrowing capacity		400,000,000
2017 Revolving Credit Facility | Revolving Credit Facility | CenturyLink Escrow, LLC | Minimum
Long-term Debt and Credit Facilities
Lending commitment per lender		36,400,000
2017 Revolving Credit Facility | Revolving Credit Facility | CenturyLink Escrow, LLC | Maximum
Long-term Debt and Credit Facilities
Lending commitment per lender		$ 167,800,000
2017 Revolving Credit Facility | Senior Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Repurchased face amount of Senior Notes								$ 319,000,000
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC
Long-term Debt and Credit Facilities
Lenders of credit facility | lender		18
Aggregate principal amount of debt issuance		$ 1,707,000,000
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC | Minimum
Long-term Debt and Credit Facilities
Lending commitment per lender		$ 28,600,000
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC | Minimum | London Interbank Offered Rate (LIBOR)
Long-term Debt and Credit Facilities
Interest rate margin		2.25%
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC | Minimum | Base Rate
Long-term Debt and Credit Facilities
Interest rate margin		1.25%
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC | Maximum
Long-term Debt and Credit Facilities
Lending commitment per lender		$ 132,200,000
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC | Maximum | London Interbank Offered Rate (LIBOR)
Long-term Debt and Credit Facilities
Interest rate margin		3.00%
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC | Maximum | Base Rate
Long-term Debt and Credit Facilities
Interest rate margin		2.00%
Term Loan A | Medium-term Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 1,622,000,000			1,575,000,000
Interest rate, stated percentage				5.272%
Term Loan A-1 | Medium-term Notes | CenturyLink Escrow, LLC
Long-term Debt and Credit Facilities
Aggregate principal amount of debt issuance		$ 370,000,000
Term Loan A-1 | Medium-term Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 351,000,000			370,000,000
Interest rate, stated percentage				5.272%
Term Loan B | Medium-term Notes | CenturyLink Escrow, LLC
Long-term Debt and Credit Facilities
Aggregate principal amount of debt issuance		$ 6,000,000,000
Interest rate, stated percentage		1.375%							2.75%
Term Loan B | Medium-term Notes | CenturyLink Escrow, LLC | London Interbank Offered Rate (LIBOR)
Long-term Debt and Credit Facilities
Interest rate margin	2.75%
Term Loan B | Medium-term Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 5,940,000,000			6,000,000,000
Interest rate, stated percentage				5.272%
Term Loan | Medium-term Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 100,000,000			100,000,000
Aggregate principal amount of debt issuance					$ 100,000,000
Term Loan | Medium-term Notes | Qwest Corporation | Minimum | London Interbank Offered Rate (LIBOR)
Long-term Debt and Credit Facilities
Interest rate margin					1.50%
Term Loan | Medium-term Notes | Qwest Corporation | Minimum | Base Rate
Long-term Debt and Credit Facilities
Interest rate margin					0.50%
Term Loan | Medium-term Notes | Qwest Corporation | Maximum | London Interbank Offered Rate (LIBOR)
Long-term Debt and Credit Facilities
Interest rate margin					2.50%
Term Loan | Medium-term Notes | Qwest Corporation | Maximum | Base Rate
Long-term Debt and Credit Facilities
Interest rate margin					1.50%
Term Loan | Medium-term Notes | Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Interest rate, stated percentage				1.25%
Uncommitted Revolving Letter of Credit Facility | Letter of Credit | CenturyLink, Inc. | Letter of Credit
Long-term Debt and Credit Facilities
Maximum borrowing capacity				$ 225,000,000
Letters of credit outstanding				97,000,000			104,000,000
Collateralized Debt Obligations | Letter of Credit | Level 3 Parent, LLC | Letter of Credit
Long-term Debt and Credit Facilities
Letters of credit outstanding				$ 24,000,000			$ 30,000,000
6.75% Notes due 2057 | Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Aggregate principal amount of debt issuance										$ 575,000,000
Interest rate, stated percentage										6.75%
Redemption price, percentage				100.00%
Principal amount of over-allotment										$ 85,000,000
Net proceeds from issuance of debt			$ 638,000,000
Qwest Notes due 2018 | Senior Notes | Qwest Capital Funding, Inc
Long-term Debt and Credit Facilities
Interest rate, stated percentage				6.50%
Repayments of debt				$ 174,000,000
Qwest Notes Due 2051 | Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage				7.50%
Repayments of debt				$ 164,000,000
Qwest Notes due 2052 | Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage				7.00%
Repayments of debt				$ 925,000,000
Qwest Notes 2035 | Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage				7.25%
Repayments of debt				$ 250,000,000
8.77% Notes due 2017 | Senior Notes | Embarq Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage							8.77%
Repurchased face amount of Senior Notes							$ 72,000,000
5.15% Notes due 2017 | Senior Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Interest rate, stated percentage							5.15%
Repurchased face amount of Senior Notes							$ 350,000,000
7.5% Notes due 2051 | Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Aggregate principal amount of debt issuance							$ 288,000,000
Interest rate, stated percentage							7.50%
Repurchased face amount of Senior Notes							$ 125,000,000
6.5% Notes due 2017 | Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage							6.50%
Repurchased face amount of Senior Notes							$ 500,000,000
6.00% Noted due 2017 | Senior Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Interest rate, stated percentage							6.00%
Repurchased face amount of Senior Notes							$ 500,000,000

Long-Term Debt and Credit Fac_5

Long-Term Debt and Credit Facilities - Long-Term Debt Maturities (Details) $ in Millions	Dec. 31, 2018USD ($)
Long-term Debt, Fiscal Year Maturity [Abstract]
2019	$ 652
2020	1,205
2021	3,115
2022	5,283
2023	2,096
2024 and thereafter	23,503
Total long-term debt	35,854
Data Centers Financing Obligation
Long-term Debt, Fiscal Year Maturity [Abstract]
Total long-term debt	558
Amount excluded from maturity	$ 499

Long-Term Debt and Credit Fac_6

Long-Term Debt and Credit Facilities - Interest Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Gross interest expense	$ 2,230	$ 1,559	$ 1,372
Capitalized interest	(53)	(78)	(54)
Total interest expense	$ 2,177	$ 1,481	$ 1,318

Accounts Receivable - Schedule

Accounts Receivable - Schedule in Accounts Receivable (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables	$ 21	$ 40
Total accounts receivable	2,540	2,721
Less: allowance for doubtful accounts	(142)	(164)
Accounts receivable, less allowance	2,398	2,557
Earned and unbilled receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	425	436
Trade and purchased receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 2,094	$ 2,245

Accounts Receivable - Activity

Accounts Receivable - Activity of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning Balance	$ 164	$ 178	$ 152
Additions	153	176	192
Deductions	(175)	(190)	(166)
Ending Balance	$ 142	$ 164	$ 178

Property, Plant and Equipment -

Property, Plant and Equipment - Schedule of Property, Plant, and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, plant and equipment
Gross property, plant and equipment	$ 53,267	$ 51,204
Accumulated depreciation	(26,859)	(24,352)
Net property, plant and equipment	26,408	26,852
Land
Property, plant and equipment
Gross property, plant and equipment	871	883
Fiber, conduit and other outside plant
Property, plant and equipment
Gross property, plant and equipment	$ 23,936	22,798
Fiber, conduit and other outside plant | Minimum
Property, plant and equipment
Depreciable Lives	15 years
Fiber, conduit and other outside plant | Maximum
Property, plant and equipment
Depreciable Lives	45 years
Central office and other network electronics
Property, plant and equipment
Gross property, plant and equipment	$ 18,736	18,538
Central office and other network electronics | Minimum
Property, plant and equipment
Depreciable Lives	3 years
Central office and other network electronics | Maximum
Property, plant and equipment
Depreciable Lives	10 years
Support assets
Property, plant and equipment
Gross property, plant and equipment	$ 8,020	7,586
Support assets | Minimum
Property, plant and equipment
Depreciable Lives	3 years
Support assets | Maximum
Property, plant and equipment
Depreciable Lives	30 years
Construction in progress
Property, plant and equipment
Gross property, plant and equipment	$ 1,704	$ 1,399

Property, Plant and Equipment_2

Property, Plant and Equipment - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Depreciation	$ 3,300	$ 2,700	$ 2,700
Change in estimate	$ 21	$ (8)	$ 0

Property, Plant and Equipment_3

Property, Plant and Equipment - Change in ARO (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Asset Retirement Obligation
Balance at beginning of year	$ 115	$ 95	$ 91
Accretion expense	10	6	6
Liabilities settled	(14)	(3)	(2)
Change in estimate	21	(8)	0
Balance at end of year	190	115	95
Colocation Business and Data Centers
Asset Retirement Obligation
Liabilities settled	0	(20)	0
Level 3 Communications, Inc.
Asset Retirement Obligation
Liabilities assumed in acquisition of Level 3	$ 58	$ 45	$ 0

Severance and Leased Real Est_3

Severance and Leased Real Estate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Severance
Restructuring reserve [Roll Forward]
Balance at the beginning of the period	$ 33	$ 98
Accrued to expense	205	42
Payments, net	(151)	(108)
Reversals and adjustments		0
Balance at the end of the period	87	33
Leased real estate
Restructuring reserve [Roll Forward]
Payments, net	(24)	(13)
Qwest Communications International Inc | Leased real estate
Severance and Leased Real Estate
Current portion of leased real estate accrual	(24)
Noncurrent portion of leased real estate accrual	$ (86)
Weighted average lease terms	6 years 8 months 15 days
Restructuring reserve [Roll Forward]
Balance at the beginning of the period	$ 64	67
Accrued to expense	70	4
Reversals and adjustments		2
Balance at the end of the period	$ 110	64
Qwest Communications International Inc | Leased real estate | Minimum
Severance and Leased Real Estate
Remaining lease terms (less than one year)	1 year
Qwest Communications International Inc | Leased real estate | Maximum
Severance and Leased Real Estate
Remaining lease terms (less than one year)	12 years 2 days
Level 3 Communications, Inc. | Severance
Restructuring reserve [Roll Forward]
Accrued to expense		1
Level 3 Communications, Inc. | Leased real estate
Restructuring reserve [Roll Forward]
Accrued to expense		$ 4

Employee Benefits - Additional

Employee Benefits - Additional Information (Details) - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2019	Nov. 01, 2017	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	$ 14,800,000,000	$ 16,500,000,000	$ 16,700,000,000
Ultimate health care cost trend rate	4.50%
Return on plan assets	$ (350,000,000)	1,300,000,000
Expected return on plan assets	(686,000,000)	(668,000,000)
Difference between the actual and expected returns on pension and post-retirement plan assets	1,000,000,000	639,000,000
Active health care benefit expenses	434,000,000	341,000,000	399,000,000
Participating employees' contribution to health care plan	$ 142,000,000	$ 128,000,000	127,000,000
CenturyLink, Inc. common stock included in the assets of the Defined Contribution Plan (in shares)	12	7
Expenses related to the 401(k) Plan	$ 93,000,000	$ 77,000,000	79,000,000
Minimum
Defined Benefit Plan Disclosure [Line Items]
Remaining estimated life of plan participants	8 years
Initial health care cost trend rate	5.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Remaining estimated life of plan participants	9 years
Initial health care cost trend rate	7.00%
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan	$ (1,561,000,000)	(2,004,000,000)
Benefit obligation	11,594,000,000	13,064,000,000	13,244,000,000			$ 13,287,000,000
Fair value of plan assets	$ 10,033,000,000	11,060,000,000	10,892,000,000			11,072,000,000
Amortization period of the plan shortfall	7 years
Employer contributions	$ 500,000,000	100,000,000	100,000,000
Benefits paid by company	0	0	0
Expected future benefits, next twelve months	966,000,000
Special termination benefits charge	$ 15,000,000	$ 0	$ 13,000,000
Expected long-term rate of return on plan assets before administrative expenses	7.00%
Expected long-term rate of return on plan assets	6.50%	6.50%	7.00%
Short term interest crediting rates	3.25%
Long term interest crediting rates	4.00%
Return on plan assets	$ (349,000,000)	$ 1,306,000,000	$ 754,000,000
Expected return on plan assets	(685,000,000)	(666,000,000)	(733,000,000)
Pension Plan | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 24,000,000	27,000,000	11,000,000
Pension Plan | Debt Security
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation, percentage	31.00%
Pension Plan | Derivatives
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation, percentage	29.00%
Pension Plan | High Yield Bonds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 7,000,000	7,000,000	11,000,000
Pension Plan | Domestic Equity Securities | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,000,000	3,000,000	0
Pension Plan | Cash and Cash Equivalents | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	1,000,000	0
Pension Plan | U.S. Stocks
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation, percentage	26.00%
Pension Plan | Private Equity
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation, percentage	14.00%
Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan	$ (1,600,000,000)	(2,000,000,000)
Employer contributions	500,000,000	100,000,000
Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan	(52,000,000)	(58,000,000)
Benefits paid by company	5,000,000	5,000,000
Expected future benefits, next twelve months	5,000,000
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan	(2,959,000,000)	(3,352,000,000)
Benefit obligation	2,977,000,000	3,375,000,000	3,413,000,000			3,567,000,000
Fair value of plan assets	18,000,000	23,000,000	53,000,000			$ 193,000,000
Employer contributions	0	0
Benefits paid by company	311,000,000	$ 298,000,000	$ 191,000,000
Expected future benefits, next twelve months	277,000,000
Benefits paid, net of participant contributions and direct subsidy receipts	249,000,000
Expected future benefit payment, next twelve months, net of direct subsidies	$ 270,000,000
Ultimate health care cost trend rate	4.50%	4.50%	4.50%
Special termination benefits charge	$ 0	$ 0	$ 3,000,000
Expected long-term rate of return on plan assets	4.00%	5.00%	7.00%
Return on plan assets	$ (1,000,000)	$ 1,000,000	$ 5,000,000
Expected return on plan assets	$ (1,000,000)	$ (2,000,000)	(7,000,000)
Other Postretirement Benefits Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost trend rate	5.00%	5.00%
Other Postretirement Benefits Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost trend rate	7.00%	7.00%
Level 3 Parent, LLC | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan	$ (11,000,000)	$ (20,000,000)			$ (20,000,000)
Benefit obligation	144,000,000	167,000,000
Fair value of plan assets	133,000,000	147,000,000
Level 3 Parent, LLC | Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan					$ 1,000,000
Scenario, Forecast | Minimum
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost trend rate				5.00%
Scenario, Forecast | Maximum
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost trend rate				6.50%
Change in Assumptions for Defined Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	(38,000,000)	(113,000,000)	$ (268,000,000)
Fair Value, Measurements, Recurring | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,108,000,000	5,441,000,000
Fair Value, Measurements, Recurring | Pension Plan | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,326,000,000	2,827,000,000
Fair Value, Measurements, Recurring | Pension Plan | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,758,000,000	2,587,000,000
Fair Value, Measurements, Recurring | Pension Plan | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	24,000,000	27,000,000
Fair Value, Measurements, Recurring | Pension Plan | Derivatives
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,000,000	2,000,000
Fair Value, Measurements, Recurring | Pension Plan | Derivatives | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7,000,000	2,000,000
Fair Value, Measurements, Recurring | Pension Plan | Derivatives | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(2,000,000)	0
Fair Value, Measurements, Recurring | Pension Plan | Derivatives | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring | Pension Plan | Investment Grade Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,851,000,000	1,747,000,000
Fair Value, Measurements, Recurring | Pension Plan | Investment Grade Bonds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	458,000,000	432,000,000
Fair Value, Measurements, Recurring | Pension Plan | Investment Grade Bonds | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,393,000,000	1,315,000,000
Fair Value, Measurements, Recurring | Pension Plan | Investment Grade Bonds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring | Pension Plan | High Yield Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	284,000,000	582,000,000
Fair Value, Measurements, Recurring | Pension Plan | High Yield Bonds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring | Pension Plan | High Yield Bonds | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	277,000,000	575,000,000
Fair Value, Measurements, Recurring | Pension Plan | High Yield Bonds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7,000,000	7,000,000
Fair Value, Measurements, Recurring | Pension Plan | U.S. Stocks
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	768,000,000	1,035,000,000
Fair Value, Measurements, Recurring | Pension Plan | U.S. Stocks | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	764,000,000	1,030,000,000
Fair Value, Measurements, Recurring | Pension Plan | U.S. Stocks | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,000,000	2,000,000
Fair Value, Measurements, Recurring | Pension Plan | U.S. Stocks | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,000,000	3,000,000
Fair Value, Measurements, Recurring | Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1,000,000
Fair Value, Measurements, Recurring | Other Postretirement Benefits Plan | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1,000,000
Fair Value, Measurements, Recurring | Other Postretirement Benefits Plan | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring | Other Postretirement Benefits Plan | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	0
Fair Value, Measurements, Recurring | Other Postretirement Benefits Plan | U.S. Stocks
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,000,000
Fair Value, Measurements, Recurring | Other Postretirement Benefits Plan | U.S. Stocks | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,000,000
Fair Value, Measurements, Recurring | Other Postretirement Benefits Plan | U.S. Stocks | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Fair Value, Measurements, Recurring | Other Postretirement Benefits Plan | U.S. Stocks | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 0

Employee Benefits - Expected Ca

Employee Benefits - Expected Cash Flows (Details) $ in Millions	Dec. 31, 2018USD ($)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
2019	$ 966
2020	938
2021	916
2022	891
2023	867
2024 - 2028	3,971
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
2019	277
2020	269
2021	261
2022	252
2023	243
2024 - 2028	1,065
Medicare Part D Subsidy Receipts
2019	(7)
2020	(7)
2021	(7)
2022	(7)
2023	(6)
2024 - 2028	$ (26)

Employee Benefits - Net Periodi

Employee Benefits - Net Periodic Benefit Costs Actuarial Assumptions (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Ultimate health care cost trend rate	4.50%
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	3.25%	3.25%	3.25%
Expected long-term rate of return on plan assets	6.50%	6.50%	7.00%
Pension Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.14%	3.25%	3.34%
Pension Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.69%	4.14%	4.46%
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.26%	3.90%	4.15%
Expected long-term rate of return on plan assets	4.00%	5.00%	7.00%
Ultimate health care cost trend rate	4.50%	4.50%	4.50%
Other Postretirement Benefits Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost trend rate	5.00%	5.00%	5.00%
Other Postretirement Benefits Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost trend rate	7.00%	7.00%	5.25%

Employee Benefits - Schedule of

Employee Benefits - Schedule of Net Periodic Benefit (Income) Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected return on plan assets	$ (686)	$ (668)
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	66	63	$ 64
Interest cost	392	409	425
Expected return on plan assets	(685)	(666)	(733)
Special termination benefits charge	15	0	13
Recognition of prior service credit	(8)	(8)	(8)
Recognition of actuarial loss	178	204	174
Net periodic pension benefit (income) expense	(42)	2	(65)
Other Postretirement Benefits Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	18	18	19
Interest cost	97	100	111
Expected return on plan assets	(1)	(2)	(7)
Special termination benefits charge	0	0	3
Recognition of prior service credit	20	20	20
Net periodic pension benefit (income) expense	$ 134	$ 136	$ 146

Employee Benefits - Benefit Obl

Employee Benefits - Benefit Obligations Actuarial Assumptions (Details)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Ultimate health care cost trend rate	4.50%
Minimum
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost trend rate	5.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost trend rate	7.00%
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.29%	3.57%
Rate of compensation increase	3.25%	3.25%
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.26%	3.53%
Ultimate health care cost trend rate	4.50%	4.50%	4.50%
Other Postretirement Benefits Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost trend rate	5.00%	5.00%
Other Postretirement Benefits Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Initial health care cost trend rate	7.00%	7.00%

Employee Benefits - Change in B

Employee Benefits - Change in Benefit Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in benefit obligation
Benefit obligation at beginning of year	$ 16,500	$ 16,700
Benefit obligation at end of year	14,800	16,500	$ 16,700
Pension Plan
Change in benefit obligation
Benefit obligation at beginning of year	13,064	13,244	13,287
Service cost	66	63	64
Interest cost	392	409	425
Plan amendments	0	0	2
Special termination benefits charge	15	0	13
Actuarial (gain) loss	(765)	586	487
Benefits paid by company	0	0	0
Benefits paid from plan assets	(1,178)	(1,238)	(1,034)
Benefit obligation at end of year	11,594	13,064	13,244
Other Postretirement Benefits Plan
Change in benefit obligation
Benefit obligation at beginning of year	3,375	3,413	3,567
Service cost	18	18	19
Interest cost	97	100	111
Participant contributions	54	54	57
Direct subsidy receipts	8	7	5
Plan amendments	(36)	0	0
Special termination benefits charge	0	0	3
Actuarial (gain) loss	(224)	112	(13)
Benefits paid by company	(311)	(298)	(191)
Benefits paid from plan assets	(4)	(31)	(145)
Benefit obligation at end of year	$ 2,977	$ 3,375	$ 3,413

Employee Benefits - Change in P

Employee Benefits - Change in Plan Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in plan assets
Return on plan assets	$ (350,000,000)	$ 1,300,000,000
Pension Plan
Change in plan assets
Fair value of plan assets at beginning of year	11,060,000,000	10,892,000,000	$ 11,072,000,000
Return on plan assets	(349,000,000)	1,306,000,000	754,000,000
Employer contributions	500,000,000	100,000,000	100,000,000
Benefits paid from plan assets	(1,178,000,000)	(1,238,000,000)	(1,034,000,000)
Fair value of plan assets at end of year	10,033,000,000	11,060,000,000	10,892,000,000
Other Postretirement Benefits Plan
Change in plan assets
Fair value of plan assets at beginning of year	23,000,000	53,000,000	193,000,000
Return on plan assets	(1,000,000)	1,000,000	5,000,000
Employer contributions	0	0
Benefits paid from plan assets	(4,000,000)	(31,000,000)	(145,000,000)
Fair value of plan assets at end of year	$ 18,000,000	$ 23,000,000	$ 53,000,000

Employee Benefits - Derivative

Employee Benefits - Derivative Instruments (Details) - Pension Plan - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Exchange Traded Domestic Equity Futures
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	$ 300	$ 256
Exchange Traded Treasury Futures
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	3,901	1,830
Interest Rate Swap
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	83	137
Credit Default Swap
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	66	100
Equity Swap
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	0	1
Foreign Exchange Forward
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	295	293
Options Held
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	$ 192	$ 259

Employee Benefits - Fair Value

Employee Benefits - Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 10,033	$ 11,060	$ 10,892	$ 11,072
Alternative investment	4,925	5,619
Pension Plan | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	24	27	11
Pension Plan | Investment Grade Bonds
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	109	163
Pension Plan | High Yield Bonds
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	388	483
Pension Plan | High Yield Bonds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	7	11
Pension Plan | Emerging Market Bonds
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	14
Pension Plan | Emerging Market Bonds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1	0
Pension Plan | Diversified Strategies
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	538
Pension Plan | U.S. Stocks
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	150	73
Pension Plan | Non-U.S. Stocks
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	500	627
Pension Plan | Emerging Market Stocks
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	75	98
Pension Plan | Private Equity
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	347	460
Pension Plan | Private Debt
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	452	374
Pension Plan | Market Neutral Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	746	769
Pension Plan | Directional Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	512	636
Pension Plan | Real estate
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	821	903
Pension Plan | Multi-Asset Strategies
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	763	424
Pension Plan | Cash Equivalents and Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	62	57
Pension Plan | Fair Value, Measurements, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,108	5,441
Pension Plan | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,326	2,827
Pension Plan | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,758	2,587
Pension Plan | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	24	27
Pension Plan | Fair Value, Measurements, Recurring | Investment Grade Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,851	1,747
Pension Plan | Fair Value, Measurements, Recurring | Investment Grade Bonds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	458	432
Pension Plan | Fair Value, Measurements, Recurring | Investment Grade Bonds | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,393	1,315
Pension Plan | Fair Value, Measurements, Recurring | Investment Grade Bonds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Plan | Fair Value, Measurements, Recurring | High Yield Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	284	582
Pension Plan | Fair Value, Measurements, Recurring | High Yield Bonds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Plan | Fair Value, Measurements, Recurring | High Yield Bonds | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	277	575
Pension Plan | Fair Value, Measurements, Recurring | High Yield Bonds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	7
Pension Plan | Fair Value, Measurements, Recurring | Emerging Market Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	332	437
Pension Plan | Fair Value, Measurements, Recurring | Emerging Market Bonds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	151	217
Pension Plan | Fair Value, Measurements, Recurring | Emerging Market Bonds | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	181	219
Pension Plan | Fair Value, Measurements, Recurring | Emerging Market Bonds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1
Pension Plan | Fair Value, Measurements, Recurring | U.S. Stocks
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	768	1,035
Pension Plan | Fair Value, Measurements, Recurring | U.S. Stocks | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	764	1,030
Pension Plan | Fair Value, Measurements, Recurring | U.S. Stocks | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	2
Pension Plan | Fair Value, Measurements, Recurring | U.S. Stocks | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	3
Pension Plan | Fair Value, Measurements, Recurring | Non-U.S. Stocks
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	601	706
Pension Plan | Fair Value, Measurements, Recurring | Non-U.S. Stocks | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	601	706
Pension Plan | Fair Value, Measurements, Recurring | Non-U.S. Stocks | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Plan | Fair Value, Measurements, Recurring | Non-U.S. Stocks | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Plan | Fair Value, Measurements, Recurring | Private Debt
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	15
Pension Plan | Fair Value, Measurements, Recurring | Private Debt | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Plan | Fair Value, Measurements, Recurring | Private Debt | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Plan | Fair Value, Measurements, Recurring | Private Debt | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	15
Pension Plan | Fair Value, Measurements, Recurring | Multi-Asset Strategies
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	342	440
Pension Plan | Fair Value, Measurements, Recurring | Multi-Asset Strategies | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	342	440
Pension Plan | Fair Value, Measurements, Recurring | Multi-Asset Strategies | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Plan | Fair Value, Measurements, Recurring | Multi-Asset Strategies | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Plan | Fair Value, Measurements, Recurring | Derivatives
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	2
Pension Plan | Fair Value, Measurements, Recurring | Derivatives | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	2
Pension Plan | Fair Value, Measurements, Recurring | Derivatives | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(2)	0
Pension Plan | Fair Value, Measurements, Recurring | Derivatives | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Plan | Fair Value, Measurements, Recurring | Cash Equivalents and Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	910	477
Pension Plan | Fair Value, Measurements, Recurring | Cash Equivalents and Short-term Investments | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	0
Pension Plan | Fair Value, Measurements, Recurring | Cash Equivalents and Short-term Investments | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	907	476
Pension Plan | Fair Value, Measurements, Recurring | Cash Equivalents and Short-term Investments | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18	23	$ 53	$ 193
Alternative investment	18	22
Other Postretirement Benefits Plan | Investment Grade Bonds
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	0
Other Postretirement Benefits Plan | High Yield Bonds
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	0
Other Postretirement Benefits Plan | Emerging Market Bonds
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	0
Other Postretirement Benefits Plan | Diversified Strategies
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	0
Other Postretirement Benefits Plan | U.S. Stocks
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	0
Other Postretirement Benefits Plan | Non-U.S. Stocks
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	0
Other Postretirement Benefits Plan | Emerging Market Stocks
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	0
Other Postretirement Benefits Plan | Private Equity
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	6	10
Other Postretirement Benefits Plan | Private Debt
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	1	1
Other Postretirement Benefits Plan | Market Neutral Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	0
Other Postretirement Benefits Plan | Directional Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	0
Other Postretirement Benefits Plan | Real estate
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	1
Other Postretirement Benefits Plan | Multi-Asset Strategies
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	0	0
Other Postretirement Benefits Plan | Cash Equivalents and Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Alternative investment	11	10
Other Postretirement Benefits Plan | Fair Value, Measurements, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1
Other Postretirement Benefits Plan | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1
Other Postretirement Benefits Plan | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits Plan | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	0
Other Postretirement Benefits Plan | Fair Value, Measurements, Recurring | U.S. Stocks
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1
Other Postretirement Benefits Plan | Fair Value, Measurements, Recurring | U.S. Stocks | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1
Other Postretirement Benefits Plan | Fair Value, Measurements, Recurring | U.S. Stocks | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Other Postretirement Benefits Plan | Fair Value, Measurements, Recurring | U.S. Stocks | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 0

Employee Benefits - Change in_2

Employee Benefits - Change in Plan Assets Measured at Fair Value (Details) - Pension Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Change in plan assets
Fair value of plan assets at beginning of year	$ 11,060	$ 10,892
Fair value of plan assets at end of year	10,033	11,060
Fair Value, Inputs, Level 3
Change in plan assets
Fair value of plan assets at beginning of year	27	11
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Assets Transferred into (out of) Level 3		13
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increases for Purchases	(3)	5
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Decreases for Sales		(2)
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held	0
Fair value of plan assets at end of year	24	27
High Yield Bonds | Fair Value, Inputs, Level 3
Change in plan assets
Fair value of plan assets at beginning of year	7	11
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Assets Transferred into (out of) Level 3		(1)
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increases for Purchases	0	2
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Decreases for Sales		(5)
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held	0
Fair value of plan assets at end of year	7	7
Emerging Market Bonds | Fair Value, Inputs, Level 3
Change in plan assets
Fair value of plan assets at beginning of year	1	0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Assets Transferred into (out of) Level 3		0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increases for Purchases	0	1
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Decreases for Sales		0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held	(1)
Fair value of plan assets at end of year	0	1
Domestic Equity Securities | Fair Value, Inputs, Level 3
Change in plan assets
Fair value of plan assets at beginning of year	3	0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Assets Transferred into (out of) Level 3		0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increases for Purchases	(2)	0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Decreases for Sales		3
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held	1
Fair value of plan assets at end of year	2	3
Private Debt | Fair Value, Inputs, Level 3
Change in plan assets
Fair value of plan assets at beginning of year	15	0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Assets Transferred into (out of) Level 3		14
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increases for Purchases	0	1
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Decreases for Sales		0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held	0
Fair value of plan assets at end of year	15	15
Cash and Cash Equivalents | Fair Value, Inputs, Level 3
Change in plan assets
Fair value of plan assets at beginning of year	1	0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Assets Transferred into (out of) Level 3		0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increases for Purchases	(1)	1
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Decreases for Sales		0
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held	0
Fair value of plan assets at end of year	$ 0	$ 1

Employee Benefits - Unfunded St

Employee Benefits - Unfunded Status (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	$ (14,800)	$ (16,500)	$ (16,700)
Non-current portion of unfunded status	(4,319)	(5,178)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	(11,594)	(13,064)	(13,244)	$ (13,287)
Fair value of plan assets	10,033	11,060	10,892	11,072
Unfunded status	(1,561)	(2,004)
Current portion of unfunded status	0	0
Non-current portion of unfunded status	(1,561)	(2,004)
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	(2,977)	(3,375)	(3,413)	(3,567)
Fair value of plan assets	18	23	$ 53	$ 193
Unfunded status	(2,959)	(3,352)
Current portion of unfunded status	(252)	(262)
Non-current portion of unfunded status	$ (2,707)	$ (3,090)

Employee Benefits - Amounts Rec

Employee Benefits - Amounts Recognized in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Net Change in Accumulated Other Comprehensive Income [Roll Forward]
Total, beginning balance	$ (1,966)	$ (2,057)
Total, recognition of net periodic benefits expense	(264)	138
Total, deferrals	(1)	(47)
Total, net change in AOCL	(265)	91
Total, ending balance	(2,231)	(1,966)
Pension Plan
Defined Benefit Plan, Net Change in Accumulated Other Comprehensive Income [Roll Forward]
Net actuarial (loss) gain, beginning balance	(2,892)	(3,148)
Net actuarial (loss) gain, recognition of net periodic benefits expense	179	205
Net actuarial (loss) gain, deferrals	(260)	51
Net actuarial (loss) gain, net change in AOCL	(81)	256
Net actuarial (loss) gain, ending balance	(2,973)	(2,892)
Prior service benefit (cost), beginning balance	54	62
Prior service benefit (cost), recognition of net periodic benefits expense	(8)	(8)
Prior service benefit (cost), deferrals	0	0
Prior service benefit (cost), net change in AOCL	(8)	(8)
Prior service benefit (cost), ending balance	46	54
Prior service benefit (cost), beginning balance	1,107	1,191
Deferred income tax benefit (expense), recognition of net periodic benefits expense	(418)	(72)
Deferred income tax benefit (expense), deferrals	65	(12)
Deferred income tax benefit (expense), net change in AOCL	(353)	(84)
Prior service benefit (cost), ending balance	754	1,107
Total, beginning balance	(1,731)	(1,895)
Total, recognition of net periodic benefits expense	(247)	125
Total, deferrals	(195)	39
Total, net change in AOCL	(442)	164
Total, ending balance	(2,173)	(1,731)
Pension Plan | Accounting Standards Update 2018-02
Defined Benefit Plan, Net Change in Accumulated Other Comprehensive Income [Roll Forward]
Deferred income tax benefit (expense), recognition of net periodic benefits expense	(375)
Other Postretirement Benefits Plan
Defined Benefit Plan, Net Change in Accumulated Other Comprehensive Income [Roll Forward]
Net actuarial (loss) gain, beginning balance	(250)	(137)
Net actuarial (loss) gain, recognition of net periodic benefits expense	0	0
Net actuarial (loss) gain, deferrals	257	(113)
Net actuarial (loss) gain, net change in AOCL	257	(113)
Net actuarial (loss) gain, ending balance	7	(250)
Prior service benefit (cost), beginning balance	(107)	(127)
Prior service benefit (cost), recognition of net periodic benefits expense	20	20
Prior service benefit (cost), deferrals	0	0
Prior service benefit (cost), net change in AOCL	20	20
Prior service benefit (cost), ending balance	(87)	(107)
Prior service benefit (cost), beginning balance	122	102
Deferred income tax benefit (expense), recognition of net periodic benefits expense	(37)	(7)
Deferred income tax benefit (expense), deferrals	(63)	27
Deferred income tax benefit (expense), net change in AOCL	(100)	20
Prior service benefit (cost), ending balance	22	122
Total, beginning balance	(235)	(162)
Total, recognition of net periodic benefits expense	(17)	13
Total, deferrals	194	(86)
Total, net change in AOCL	177	(73)
Total, ending balance	(58)	$ (235)
Other Postretirement Benefits Plan | Accounting Standards Update 2018-02
Defined Benefit Plan, Net Change in Accumulated Other Comprehensive Income [Roll Forward]
Deferred income tax benefit (expense), recognition of net periodic benefits expense	$ (32)

Share-based Compensation (Detai

Share-based Compensation (Details) $ / shares in Units, shares in Thousands, $ in Millions	Nov. 01, 2017USD ($)$ / shares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Oct. 31, 2017$ / shares
Share-based compensation, aggregate disclosures
Compensation cost | $		$ 185	$ 111	$ 80
Tax benefit recognized in the income statement for share-based payment arrangements | $		46	$ 28	31
Unrecognized compensation cost | $		$ 215
Weighted-average recognition period		1 year 8 months 12 days
Restricted Stock Units (RSUs) | Minimum
Share-based compensation
Vesting period		1 year
Restricted Stock Units (RSUs) | Maximum
Share-based compensation
Vesting period		2 years
Stock options
Share-based compensation
Option expiration term (in years)		10 years
Summary of stock options activity
Outstanding, beginning balance | shares		1,022
Exercised | shares		(178)
Forfeited/Expired | shares		(301)
Outstanding, ending balance | shares		543	1,022
Summary of stock options weighted-average exercise price activity
Exercisable, beginning balance (in dollars per share)			$ 27.41
Exercised (in dollars per share)		$ 22.49
Forfeited/Expired (in dollars per share)		30.25
Exercisable, ending balance (in dollars per share)		$ 27.46
Stock options additional disclosures
Outstanding at the end of the period, intrinsic value | $		$ 1
Outstanding options weighted-average remaining contractual term		1 year 1 month 13 days
Net cash proceeds received in connection with option exercises (less than $1 million) | $		$ 4
Tax benefit realized from option exercises (less than $1 million) | $		1
Total intrinsic value of options exercised (less than $1 million) | $		$ 1	$ 1	1
Restricted Stock
Summary of restricted stock and restricted stock unit activity
Nonvested at the beginning of the period (in shares) | shares		19,774
Granted (in shares) | shares		9,657
Vested (in shares) | shares		(9,275)
Forfeited (in shares) | shares		(3,097)
Nonvested at the end of the period (in shares) | shares		17,059	19,774
Weighted-Average Grant Date Fair Value
Nonvested at the beginning of the period (in dollars per share)		$ 21.90
Granted (in dollars per share)		17.02
Vested (in dollars per share)		20.87
Forfeited (in dollars per share)		22.12
Nonvested at the end of the period (in dollars per share)		$ 19.65	$ 21.90
Total fair value of awards vested during the period | $		$ 169	$ 60	$ 47
Restricted Stock | Minimum
Restricted stock awards
Percentage of target award (as a percent)		0.00%
Restricted Stock | Maximum
Restricted stock awards
Percentage of target award (as a percent)		200.00%
Restricted Stock and Restricted Stock Units (RSUs)
Summary of restricted stock and restricted stock unit activity
Granted (in shares) | shares			5,200	3,600
Weighted-Average Grant Date Fair Value
Granted (in dollars per share)			$ 22.02	$ 30.83
Service conditions | Restricted Stock | Minimum
Share-based compensation
Vesting period		3 years
Services conditions and either market or performance conditions | Restricted Stock
Share-based compensation
Vesting period		3 years
Level 3 Parent, LLC
Share-based compensation
Price per share of stock in business acquisition (in dollars per share)	$ 26.50
Stock conversion ratio	1.4286
Price of share of common stock (in dollars per share)					$ 18.99
Level 3 Parent, LLC | Restricted Stock Units (RSUs)
Share-based compensation
Stock conversion ratio	2.8386
Preliminary aggregate fair value of Level 3 RSUs at acquisition | $	$ 239
Nonvested Continuing RSUs compensation not yet recognized | $		$ 137
Weighted-Average Grant Date Fair Value
Total fair value of awards vested during the period | $	$ 103
Level 3 Parent, LLC | Restricted Stock
Share-based compensation
Price per share of stock in business acquisition (in dollars per share)	$ 26.50
Stock conversion ratio	1.4286
Level 3 Parent, LLC | Common Stock
Share-based compensation
Price of share of common stock (in dollars per share)	$ 18.99

(Loss) Earnings Per Common Sh_3

(Loss) Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loss income (Numerator):
Net (loss) income	$ (2,412)	$ 272	$ 292	$ 115	$ 1,117	$ 92	$ 17	$ 163	$ (1,733)	$ 1,389	$ 626
Net (loss) income applicable to common stock for computing basic earnings per common share									(1,733)	1,389	626
Net (loss) income as adjusted for purposes of computing diluted earnings per common share									$ (1,733)	$ 1,389	$ 626
Number of shares of common stock excluded from the computation of diluted earnings per share									2,700	4,700	3,300
Weighted average number of shares:
Outstanding during period (in shares)									1,078,409	635,576	545,946
Non-vested restricted stock (in shares)									(12,543)	(7,768)	(6,397)
Weighted average shares outstanding for computing basic earnings per common share (in shares)									1,065,866	627,808	539,549
Incremental common shares attributable to dilutive securities:
Shares issuable under convertible securities (in shares)									0	10	10
Shares issuable under incentive compensation plans (in shares)									0	875	1,120
Number of shares as adjusted for purposes of computing diluted earnings per common share (in shares)									1,065,866	628,693	540,679
Basic (loss) earnings per common share (in dollars per share)	$ (2.26)	$ 0.25	$ 0.27	$ 0.11	$ 1.26	$ 0.17	$ 0.03	$ 0.30	$ (1.63)	$ 2.21	$ 1.16
Diluted (loss) earnings per common share (in dollars per share)	$ (2.26)	$ 0.25	$ 0.27	$ 0.11	$ 1.26	$ 0.17	$ 0.03	$ 0.30	$ (1.63)	$ 2.21	$ 1.16
Stock compensation plan
Loss income (Numerator):
Number of shares of common stock excluded from the computation of diluted earnings per share									4,600

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Details) - Fair value measurements determined on a nonrecurring basis - Fair value, Input Level 2 - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Carrying amount
Liabilities
Liabilities-Long-term debt, excluding capital lease and other obligations	$ 35,260	$ 36,835
Fair value amount
Liabilities
Liabilities-Long-term debt, excluding capital lease and other obligations	$ 32,915	$ 36,402

Income Taxes - Income Taxes (De

Income Taxes - Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Provisional tax benefit, amount		$ 1,100
Purchase accounting adjustment	$ (92)
Income tax expense
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Income Tax Expense	11
Federal
Current	(576)	82	$ 335
Deferred	734	(988)	5
State
Current	(22)	21	27
Deferred	52	16	8
Foreign
Current	36	22	26
Deferred	(54)	(2)	(7)
Total income tax expense	170	(849)	394
Income tax expense allocation
Attributable to income	170	(849)	394
Stockholders' equity:
Compensation expense for tax purposes in excess of amounts recognized for financial reporting purposes	0	0	(2)
Tax effect of the change in accumulated other comprehensive loss	$ (2)	$ 81	$ (109)
Reconciliation of the statutory federal income tax rate to effective income tax rate
Statutory federal income tax rate	21.00%	35.00%	35.00%
State income taxes, net of federal income tax benefit	(1.50%)	3.90%	2.30%
Impairment of goodwill	(36.60%)	0.00%	0.00%
Change in liability for unrecognized tax position	1.30%	1.00%	0.20%
Tax reform	(5.90%)	(209.80%)	0.00%
Net foreign income taxes	1.80%	(0.70%)	0.10%
Foreign dividend paid to a domestic parent company	0.00%	0.20%	1.80%
Research and development credits	0.90%	(1.40%)	(0.60%)
Tax impact on sale of data centers and colocation business	0.00%	5.00%	0.00%
Tax benefit of net operating loss carryback	9.10%	(0.00%)	(0.00%)
Level 3 acquisition transaction costs	0.00%	6.00%	0.00%
Other, net	(1.00%)	3.60%	(0.20%)
Effective income tax rate	(10.90%)	(157.20%)	38.60%
Impairment losses	$ 572
Operating loss carrybacks, amount	142
Tax expense related to sale of colocation business		$ 27
Transaction costs		32
Foreign dividend paid to a domestic parent company			$ 18
Deferred tax assets
Post-retirement and pension benefit costs	1,111	1,321
Net operating loss carryforwards	3,445	3,951
Other employee benefits	162	112
Other	553	714
Gross deferred tax assets	5,271	6,098
Less valuation allowance	(1,331)	(1,341)
Net deferred tax assets	3,940	4,757
Deferred tax liabilities
Property, plant and equipment, primarily due to depreciation differences	(3,011)	(2,935)
Goodwill and other intangible assets	(3,303)	(3,785)
Other	(23)	(16)
Gross deferred tax liabilities	(6,337)	(6,736)
Net deferred tax liability	(2,397)	(1,979)
Deferred tax liabilities, noncurrent	2,500	2,400
Net deferred tax assets	131	434
Valuation allowance, DTA, increase (decrease), amount	10
Summary of reconciliation of the change in gross unrecognized tax benefits activity
Unrecognized tax benefits at beginning of year	40	16
Assumed in the acquisition of Level 3	0	18
Tax position of prior periods netted against deferred tax assets	1,338	2
Increase in tax positions taken in the current year	4	1
Increase in tax positions taken in the prior year	211	3
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(1)	0
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	(2)	0
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	(3)	0
Unrecognized tax benefits at end of year	1,587	40	$ 16
Unrecognized tax benefits that would impact effective tax rate	256	66
Interest on income taxes accrued	17	$ 56
Significant change in unrecorded benefit	12
Federal
Deferred tax liabilities
Operating loss carryforward	7,287
Tax credit carryforward, amount	52
Summary of reconciliation of the change in gross unrecognized tax benefits activity
Unrecognized tax benefits at end of year	5,526
State
Deferred tax liabilities
Operating loss carryforward	19,000
Foreign
Deferred tax liabilities
Operating loss carryforward	$ 6,000

Income Taxes - Schedule of Net

Income Taxes - Schedule of Net Operating Loss (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Uncertain tax positions	$ (1,587)	$ (40)	$ (16)
Federal
Operating Loss Carryforwards [Line Items]
NOLs per return	12,813
Uncertain tax positions	(5,526)
Financial NOLs	7,287
Federal | Tax Year 2022
Operating Loss Carryforwards [Line Items]
NOLs per return	1,043
Federal | Tax Year 2023
Operating Loss Carryforwards [Line Items]
NOLs per return	1,440
Federal | Tax Year 2024
Operating Loss Carryforwards [Line Items]
NOLs per return	1,402
Federal | Tax Year 2025
Operating Loss Carryforwards [Line Items]
NOLs per return	1,042
Federal | Tax Year 2026
Operating Loss Carryforwards [Line Items]
NOLs per return	1,525
Federal | Tax Year 2027
Operating Loss Carryforwards [Line Items]
NOLs per return	375
Federal | Tax Year 2028
Operating Loss Carryforwards [Line Items]
NOLs per return	637
Federal | Tax Year 2029
Operating Loss Carryforwards [Line Items]
NOLs per return	645
Federal | Tax Year 2030
Operating Loss Carryforwards [Line Items]
NOLs per return	671
Federal | Tax Year 2031
Operating Loss Carryforwards [Line Items]
NOLs per return	732
Federal | Tax Year 2032
Operating Loss Carryforwards [Line Items]
NOLs per return	348
Federal | Tax Year 2033
Operating Loss Carryforwards [Line Items]
NOLs per return	238
Federal | Tax Year 2037
Operating Loss Carryforwards [Line Items]
NOLs per return	$ 2,715

Segment Information (Details)

Segment Information (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments (segments) | segment									2
Operating revenue	$ 5,778	$ 5,818	$ 5,902	$ 5,945	$ 5,323	$ 4,034	$ 4,090	$ 4,209	$ 23,443	$ 17,656	$ 17,470
Total segment expenses									22,873	15,647	15,137
Operating Segments
Segment Reporting Information [Line Items]
Operating revenue									22,720	16,924	16,766
Total segment expenses									12,269	9,390	9,081
Total segment adjusted EBITDA									$ 10,451	$ 7,534	$ 7,685
Total margin percentage									46.00%	45.00%	46.00%
Business
Segment Reporting Information [Line Items]
Operating revenue									$ 17,349	$ 11,220	$ 10,704
Total segment expenses									10,076	6,847	6,391
Total segment adjusted EBITDA									$ 7,273	$ 4,373	$ 4,313
Total margin percentage									42.00%	39.00%	40.00%
Consumer
Segment Reporting Information [Line Items]
Operating revenue									$ 5,371	$ 5,704	$ 6,062
Total segment expenses									2,193	2,543	2,690
Total segment adjusted EBITDA									$ 3,178	$ 3,161	$ 3,372
Total margin percentage									59.00%	55.00%	56.00%

Segment Information (Details 2)

Segment Information (Details 2) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)category	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Operating revenues by products and services
Number of categories of products and services (categories) | category									5
Operating revenue	$ 5,778	$ 5,818	$ 5,902	$ 5,945	$ 5,323	$ 4,034	$ 4,090	$ 4,209	$ 23,443	$ 17,656	$ 17,470
Surcharge amount on customers' bills									952	601	572
Business
Operating revenues by products and services
Operating revenue									17,349	11,220	10,704
Consumer
Operating revenues by products and services
Operating revenue									5,371	5,704	6,062
Operating Segments | Business
Operating revenues by products and services
Operating revenue									17,349	11,220	10,704
Operating Segments | Business | IP & Data Services
Operating revenues by products and services
Operating revenue									6,971	3,682	2,957
Operating Segments | Business | Transport & Infrastructure
Operating revenues by products and services
Operating revenue									5,356	3,569	3,807
Operating Segments | Business | Voice & Collaboration
Operating revenues by products and services
Operating revenue									4,401	3,317	3,299
Operating Segments | Business | IT & Managed Services
Operating revenues by products and services
Operating revenue									621	652	641
Operating Segments | Consumer
Operating revenues by products and services
Operating revenue									5,371	5,704	6,062
Operating Segments | Consumer | IP & Data Services
Operating revenues by products and services
Operating revenue									308	401	461
Operating Segments | Consumer | Transport & Infrastructure
Operating revenues by products and services
Operating revenue									2,892	2,776	2,776
Operating Segments | Consumer | Voice & Collaboration
Operating revenues by products and services
Operating revenue									2,171	2,527	2,825
Corporate, Non-Segment
Operating revenues by products and services
Operating revenue									723	732	704
Corporate, Non-Segment | Regulatory Revenue
Operating revenues by products and services
Operating revenue									$ 723	$ 732	$ 704

Segment Information (Details 3)

Segment Information (Details 3) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization									$ (5,120)	$ (3,936)	$ (3,916)
Impairment of goodwill									(2,726)	0	0
Total other expenses, net									(2,133)	(1,469)	(1,313)
Income (loss) before income tax expense									(1,563)	540	1,020
Income tax (expense) benefit									(170)	849	(394)
Net (loss) income	$ (2,412)	$ 272	$ 292	$ 115	$ 1,117	$ 92	$ 17	$ 163	(1,733)	1,389	626
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment adjusted EBITDA									10,451	7,534	7,685
Unallocated amount to segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Regulatory Revenue									723	732	704
Depreciation and amortization									(5,120)	(3,936)	(3,916)
Impairment of goodwill									(2,726)	0	0
Other operating expenses									(2,758)	(2,321)	(2,140)
Total other expenses, net									$ (2,133)	$ (1,469)	$ (1,313)

Quarterly Financial Data (Una_3

Quarterly Financial Data (Unaudited) (Details) - USD ($)	3 Months Ended								4 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	May 01, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 19, 2017
Operating revenues by products and services
Operating revenue	$ 5,778,000,000	$ 5,818,000,000	$ 5,902,000,000	$ 5,945,000,000	$ 5,323,000,000	$ 4,034,000,000	$ 4,090,000,000	$ 4,209,000,000		$ 23,443,000,000	$ 17,656,000,000	$ 17,470,000,000
Operating income (loss)	(1,841,000,000)	894,000,000	767,000,000	750,000,000	524,000,000	487,000,000	367,000,000	631,000,000		570,000,000	2,009,000,000	2,333,000,000
Net (loss) income	$ (2,412,000,000)	$ 272,000,000	$ 292,000,000	$ 115,000,000	$ 1,117,000,000	$ 92,000,000	$ 17,000,000	$ 163,000,000		$ (1,733,000,000)	$ 1,389,000,000	$ 626,000,000
Basic (loss) earnings per common share (in dollars per share)	$ (2.26)	$ 0.25	$ 0.27	$ 0.11	$ 1.26	$ 0.17	$ 0.03	$ 0.30		$ (1.63)	$ 2.21	$ 1.16
Diluted (loss) earnings per common share (in dollars per share)	$ (2.26)	$ 0.25	$ 0.27	$ 0.11	$ 1.26	$ 0.17	$ 0.03	$ 0.30		$ (1.63)	$ 2.21	$ 1.16
Goodwill impairment										$ 2,726,000,000	$ 0	$ 0
Acquisition related costs	$ 117,000,000	$ 43,000,000	$ 162,000,000	$ 71,000,000	$ 206,000,000	$ 37,000,000	$ 18,000,000	$ 10,000,000
Provisional tax benefit, amount											$ 1,100,000,000
Statutory federal income tax rate										21.00%	35.00%	35.00%
Term Loan B
Operating revenues by products and services
Interest expense related to Term loan B					$ 20,000,000	$ 44,000,000
Term Loan B | Medium-term Notes | CenturyLink Escrow, LLC
Operating revenues by products and services
Debt instrument, face amount													$ 6,000,000,000
Cyxtera Technologies
Operating revenues by products and services
Operating revenue										$ 74,000,000	$ 49,000,000
Net (loss) income										(21,000,000)	(103,000,000)
Gain (Loss) on asset leaseback, failed-sale-leaseback transaction							(119,000,000)			(102,000,000)
Depreciation expense on reclassified assets							$ 44,000,000			$ 0	$ 44,000,000
Colocation Business and Data Centers
Operating revenues by products and services
Depreciation and amortization								$ 50,000,000	$ 67,000,000

Commitments, Contingencies an_2

Commitments, Contingencies and Other Items (Details)	1 Months Ended	9 Months Ended	12 Months Ended
	Feb. 28, 2017USD ($)lawsuit	Dec. 31, 2018USD ($)lawsuit	Dec. 31, 2018USD ($)patentpropertylawsuit	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Commitments and Contingencies
Proceeds from Rents Received			$ 882,000,000	$ 766,000,000	$ 734,000,000
Litigation liability		$ 123,000,000	$ 123,000,000
Number of patents allegedly infringed, minimum | patent			1
Lease expense			$ 875,000,000	550,000,000	482,000,000
Capital lease activity
Assets acquired through capital leases			25,000,000	35,000,000	45,000,000
Depreciation expense			51,000,000	50,000,000	70,000,000
Cash payments towards capital leases			48,000,000	48,000,000	58,000,000
Assets included in property, plant and equipment		427,000,000	427,000,000	420,000,000
Accumulated depreciation		180,000,000	180,000,000	154,000,000
Future annual minimum payments under capital lease arrangements
2019		51,000,000	51,000,000
2020		36,000,000	36,000,000
2021		23,000,000	23,000,000
2022		21,000,000	21,000,000
2023		20,000,000	20,000,000
2024 and thereafter		183,000,000	183,000,000
Total minimum payments		334,000,000	334,000,000
Less: amount representing interest and executory costs		(100,000,000)	(100,000,000)
Present value of minimum payments		234,000,000	234,000,000
Less: current portion		(38,000,000)	(38,000,000)
Long-term portion		196,000,000	196,000,000
Future rental commitments
2019		832,000,000	832,000,000
2020		577,000,000	577,000,000
2021		467,000,000	467,000,000
2022		399,000,000	399,000,000
2023		356,000,000	356,000,000
2024 and thereafter		1,724,000,000	1,724,000,000
Total future minimum payments		4,355,000,000	4,355,000,000
Minimum sublease rentals due in the future under non-cancelable subleases		101,000,000	101,000,000
Purchase obligations maturities
Total purchase commitments		921,000,000	921,000,000
2019		322,000,000	322,000,000
2020 and 2021		325,000,000	325,000,000
2022 and 2023		88,000,000	88,000,000
2024 and thereafter		186,000,000	186,000,000
Operating Leases, Income Statement, Sublease Revenue			$ 21,000,000	$ 13,000,000	$ 12,000,000
Site Contingency, Number Of Properties With Potential Environmental Liability | property			200
Unfavorable regulatory action
Commitments and Contingencies
Reasonable expectation of loss, maximum per proceeding		100,000,000	$ 100,000,000
Right-of-Way Agreements
Future rental commitments
2019		157,000,000	157,000,000
2020		134,000,000	134,000,000
2021		112,000,000	112,000,000
2022		120,000,000	120,000,000
2023		115,000,000	115,000,000
2024 and thereafter		755,000,000	755,000,000
Total future minimum payments		1,393,000,000	1,393,000,000
Operating Leases
Future rental commitments
2019		675,000,000	675,000,000
2020		443,000,000	443,000,000
2021		355,000,000	355,000,000
2022		279,000,000	279,000,000
2023		241,000,000	241,000,000
2024 and thereafter		969,000,000	969,000,000
Total future minimum payments		$ 2,962,000,000	2,962,000,000
Louisiana State Court
Commitments and Contingencies
Loss Contingency, New Claims Filed, Number | lawsuit		2
Level 3 Parent, LLC
Commitments and Contingencies
Loss contingency, damages sought, value			50,000,000
Level 3 Parent, LLC | Pending litigation | Peruvian Tax Litigation, Before Interest
Commitments and Contingencies
Loss contingency, asserted claim						$ 26,000,000
Level 3 Parent, LLC | Pending litigation | Peruvian Tax Litigation
Commitments and Contingencies
Loss contingency, asserted claim		$ 11,000,000	11,000,000
Level 3 Parent, LLC | Pending litigation | Maximum | Brazilian Tax Claims
Commitments and Contingencies
Loss contingency, range of possible loss, portion not accrued		$ 37,000,000	$ 37,000,000
Interexchange Carriers | CenturyLink, Inc.
Commitments and Contingencies
Loss contingency, pending claims, number | lawsuit		100	100
Missouri Municipalities | Judicial ruling
Commitments and Contingencies
Pending cases, final order | lawsuit	1
Litigation settlement, amount awarded to other party	$ 4,000,000

Other Financial Information (De

Other Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Prepaid Expenses and Other Current Assets [Abstract]
Prepaid expenses	$ 307	$ 294
Income tax receivable	82	258
Materials, supplies and inventory	120	128
Contract assets	134	0
Contract acquisition costs and deferred activation and installation charges	167	128
Other	108	133
Total other current assets	918	941
Accounts Payable, Current [Abstract]
Accounts payable	1,933	1,555
Other current liabilities:
Accrued rent	45	34
Legal contingencies	30	45
Other	282	265
Total other current liabilities	357	344
Book overdraft balance	86	36
Capital expenditures included in accounts payable	$ 434	$ 225

Labor Union Contracts (Details)

Labor Union Contracts (Details)	12 Months Ended
	Dec. 31, 2018
Workforce subject to collective bargaining agreements, expired in 2017
Labor Union Contracts
Concentration risk (percent)	1.00%
Total number of employees | Unionized employees concentration risk
Labor Union Contracts
Concentration risk (percent)	26.00%
Total number of employees | Unionized employees concentration risk | Workforce subject to collective bargaining arrangements expiring within one year
Labor Union Contracts
Concentration risk (percent)	2.00%

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 23,491	$ 13,399
Accumulated other comprehensive income (loss) by component
Other comprehensive loss before reclassifications	(202)	(16)
Amounts reclassified from accumulated other comprehensive loss	143	138
Net current-period other comprehensive income (loss)	(59)	122	$ (183)
Balance at end of period	19,828	23,491	13,399
Defined Benefit Plans
Accumulated other comprehensive income (loss) by component
Amounts reclassified from accumulated other comprehensive loss	143	138
Defined Benefit Plans | Pension Plan
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(1,731)	(1,895)
Accumulated other comprehensive income (loss) by component
Other comprehensive loss before reclassifications	(195)	39
Amounts reclassified from accumulated other comprehensive loss	128	125
Net current-period other comprehensive income (loss)	(67)	164
Balance at end of period	(2,173)	(1,731)	(1,895)
Defined Benefit Plans | Other Postretirement Benefits Plan
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(235)	(162)
Accumulated other comprehensive income (loss) by component
Other comprehensive loss before reclassifications	194	(86)
Amounts reclassified from accumulated other comprehensive loss	15	13
Net current-period other comprehensive income (loss)	209	(73)
Balance at end of period	(58)	(235)	(162)
Foreign Currency Translation Adjustment and Other
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(29)	(60)
Accumulated other comprehensive income (loss) by component
Other comprehensive loss before reclassifications	(201)	31
Amounts reclassified from accumulated other comprehensive loss	0	0
Net current-period other comprehensive income (loss)	(201)	31
Balance at end of period	(230)	(29)	(60)
AOCI Attributable to Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(1,995)	(2,117)	(1,934)
Accumulated other comprehensive income (loss) by component
Net current-period other comprehensive income (loss)	(59)	122	(183)
Balance at end of period	(2,461)	$ (1,995)	$ (2,117)
Accounting Standards Update 2018-02
Accumulated other comprehensive income (loss) by component
Amounts reclassified from accumulated other comprehensive loss	(407)
Accounting Standards Update 2018-02 | Defined Benefit Plans | Pension Plan
Accumulated other comprehensive income (loss) by component
Amounts reclassified from accumulated other comprehensive loss	(375)
Accounting Standards Update 2018-02 | Defined Benefit Plans | Other Postretirement Benefits Plan
Accumulated other comprehensive income (loss) by component
Amounts reclassified from accumulated other comprehensive loss	(32)
Accounting Standards Update 2018-02 | Foreign Currency Translation Adjustment and Other
Accumulated other comprehensive income (loss) by component
Amounts reclassified from accumulated other comprehensive loss	$ 0

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Loss (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	$ 143	$ 138
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net actuarial loss and prior service cost	178	(205)
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net actuarial loss and prior service cost	12	(12)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net actuarial loss and prior service cost	(190)	(217)
Income tax benefit	(47)	(79)
Net of tax	$ 143	$ 138

Dividends (Details)

Dividends (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 01, 2019	Nov. 14, 2018	Aug. 21, 2018	May 23, 2018	Feb. 21, 2018	Nov. 14, 2017	Aug. 22, 2017	May 24, 2017	Feb. 21, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Subsequent Event [Line Items]
Dividend per share (usd per share)		$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.540	$ 0.540	$ 0.540	$ 0.540	$ 2.16	$ 2.16	$ 2.16
Total amount declared		$ 586	$ 584	$ 588	$ 586	$ 577	$ 296	$ 297	$ 295
Subsequent event
Subsequent Event [Line Items]
Dividend per share (usd per share)	$ 0.25