Delta Air Lines (DAL) 10-K 12 Feb 21 2020 FY Annual report Financial data

Cover

Cover - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Jan. 31, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-5424
Entity Registrant Name	DELTA AIR LINES, INC.
Entity Central Index Key	0000027904
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	58-0218548
Entity Address, Address Line One	Post Office Box 20706
Entity Address, City or Town	Atlanta
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30320-6001
City Area Code	404
Local Phone Number	715-2600
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	DAL
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 17.9
Entity Common Stock, Shares Outstanding		638,146,665
Documents Incorporated by Reference	Part III of this Form 10-K incorporates by reference certain information from the registrant's definitive Proxy Statement for its 2021 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current Assets:
Cash and cash equivalents	$ 8,307	$ 2,882
Short-term investments	5,789	0
Accounts receivable, net of an allowance for uncollectible accounts of $89 and $13 as of 2020 and 2019, respectively	1,396	2,854
Fuel inventory	377	730
Expendable parts and supplies inventories, net of an allowance for obsolescence of $188 and $82 as of 2020 and 2019, respectively	355	521
Prepaid expenses and other	1,180	1,262
Total current assets	17,404	8,249
Noncurrent Assets:
Property and equipment, net of accumulated depreciation and amortization of $17,511 and $17,027 as of 2020 and 2019, respectively	26,529	31,310
Operating lease right-of-use assets	5,733	5,627
Goodwill	9,753	9,781
Identifiable intangibles, net of accumulated amortization of $883 and $873 as of 2020 and 2019, respectively	6,011	5,163
Cash restricted for airport construction	1,556	636
Equity investments	1,665	2,568
Deferred income taxes, net	1,988	120
Other noncurrent assets	1,357	1,078
Total noncurrent assets	54,592	56,283
Total assets	71,996	64,532
Current Liabilities:
Current maturities of debt and finance leases	1,732	2,287
Current maturities of operating leases	678	801
Accounts payable	2,840	3,266
Accrued salaries and related benefits	2,086	3,701
Fuel card obligation	1,100	736
Other accrued liabilities	1,670	1,078
Total current liabilities	15,927	20,204
Noncurrent Liabilities:
Debt and finance leases	27,425	8,873
Pension, postretirement and related benefits	10,630	8,452
Noncurrent operating leases	5,713	5,294
Deferred income taxes, net	0	1,456
Other noncurrent liabilities	4,862	1,386
Total noncurrent liabilities	54,535	28,970
Commitments and Contingencies
Stockholders' Equity:
Common stock at $0.0001 par value; 1,500,000,000 shares authorized, 647,352,203 and 651,731,443 shares issued as of 2020 and 2019, respectively	0	0
Additional paid-in capital	11,259	11,129
Retained earnings/(deficit)	(428)	12,454
Accumulated other comprehensive loss	(9,038)	(7,989)
Treasury stock, at cost, 9,169,683 and 8,959,730 shares as of 2020 and 2019, respectively	(259)	(236)
Total stockholders' equity	1,534	15,358
Total liabilities and stockholders' equity	71,996	64,532
Air traffic
Current Liabilities:
Deferred revenue liability, current	4,044	5,116
Noncurrent Liabilities:
Deferred revenue liability, noncurrent	500	0
Loyalty program
Current Liabilities:
Deferred revenue liability, current	1,777	3,219
Noncurrent Liabilities:
Deferred revenue liability, noncurrent	$ 5,405	$ 3,509

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current Assets:
Allowance for uncollectible accounts	$ 89	$ 13
Allowance for obsolescence	188	82
Noncurrent Assets:
Accumulated depreciation and amortization	17,511	17,027
Accumulated amortization	$ 883	$ 873
Stockholders' Equity:
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (shares)	1,500,000,000	1,500,000,000
Common stock, shares issued (shares)	647,352,203	651,731,443
Treasury stock, at cost (shares)	9,169,683	8,959,730

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Revenue:
Operating revenue	$ 17,095	$ 47,007	$ 44,438
Operating Expense:
Salaries and related costs	8,754	11,225	10,743
Aircraft fuel and related taxes	3,176	8,519	9,020
Regional carriers expense, excluding fuel	2,479	3,584	3,438
Depreciation and amortization	2,312	2,581	2,329
Ancillary businesses and refinery	1,785	1,245	1,695
Contracted services	1,778	2,641	2,175
Landing fees and other rents	1,518	1,762	1,662
Aircraft maintenance materials and outside repairs	822	1,751	1,575
Passenger commissions and other selling expenses	582	1,993	1,941
Passenger service	523	1,251	1,178
Aircraft rent	399	423	394
Restructuring charges	8,219	0	0
Government grant recognition	(3,946)	0	0
Profit sharing	0	1,643	1,301
Other	1,163	1,771	1,723
Total operating expense	29,564	40,389	39,174
Operating (Loss)/Income	(12,469)	6,618	5,264
Non-Operating Expense:
Interest expense, net	(929)	(301)	(311)
Impairments and equity method losses	(2,432)	(62)	(60)
Gain/(loss) on investments, net	(105)	119	38
Miscellaneous, net	348	(176)	220
Total non-operating expense, net	(3,118)	(420)	(113)
(Loss)/Income Before Income Taxes	(15,587)	6,198	5,151
Income Tax Benefit/(Provision)	3,202	(1,431)	(1,216)
Net (Loss)/Income	$ (12,385)	$ 4,767	$ 3,935
Basic (Loss) Earnings Per Share (usd per share)	$ (19.49)	$ 7.32	$ 5.69
Diluted (Loss) Earnings Per Share (usd per share)	(19.49)	7.30	5.67
Cash Dividends Declared Per Share (usd per share)	$ 0.40	$ 1.51	$ 1.31
Passenger
Operating Revenue:
Operating revenue	$ 12,883	$ 42,277	$ 39,755
Cargo
Operating Revenue:
Operating revenue	608	753	865
Other
Operating Revenue:
Operating revenue	$ 3,604	$ 3,977	$ 3,818

Consolidated Statements of Comp

Consolidated Statements of Comprehensive (Loss)/Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net (Loss)/Income	$ (12,385)	$ 4,767	$ 3,935
Other comprehensive (loss)/income:
Net change in derivative contracts and other	(66)	6	15
Net change in pension and other benefits	(983)	(170)	(113)
Total Other Comprehensive (Loss)/Income	(1,049)	(164)	(98)
Comprehensive (Loss)/Income	$ (13,434)	$ 4,603	$ 3,837

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows From Operating Activities:
Net (loss)/income	$ (12,385)	$ 4,767	$ 3,935
Adjustments to reconcile net income to net cash provided by operating activities:
Restructuring charges	4,111	0	0
Depreciation and amortization	2,312	2,581	2,329
Deferred income taxes	(3,110)	1,473	1,364
Pension, postretirement and postemployment payments less/(greater) than expense	898	(922)	(790)
Impairments and equity method losses	2,432	62	60
Changes in certain assets and liabilities:
Receivables	1,168	(775)	108
Fuel inventory	354	(139)	324
Noncurrent assets	210	111	(221)
Profit sharing	(1,650)	354	233
Other payables, deferred revenue and accrued liabilities	240	144	(418)
Noncurrent liabilities	1,185	(16)	47
Other, net	559	244	(573)
Net cash (used in)/provided by operating activities	(3,793)	8,425	7,014
Property and equipment additions:
Flight equipment, including advance payments	(896)	(3,344)	(3,704)
Ground property and equipment, including technology	(1,003)	(1,592)	(1,464)
Proceeds from sale-leaseback transactions	465	0	0
Purchase of equity investments	(2,099)	(170)	0
Sale of equity investments	0	279	28
Purchase of short-term investments	(13,400)	0	(145)
Redemption of short-term investments	7,608	206	766
Other, net	87	58	126
Net cash used in investing activities	(9,238)	(4,563)	(4,393)
Cash Flows From Financing Activities:
Proceeds from short-term obligations	3,261	1,750	0
Proceeds from long-term obligations	22,790	2,057	3,745
Proceeds from sale-leaseback transactions	2,306	0	0
Payments on debt and finance lease obligations	(8,559)	(3,320)	(3,052)
Repurchase of common stock	(344)	(2,027)	(1,575)
Cash dividends	(260)	(980)	(909)
Fuel card obligation	364		7
Fuel card obligation		(339)
Other, net	(202)	(21)	58
Net cash provided by/(used in) financing activities	19,356	(2,880)	(1,726)
Net Increase in Cash, Cash Equivalents and Restricted Cash	6,325	982	895
Cash, cash equivalents and restricted cash at beginning of period	3,730	2,748	1,853
Cash, cash equivalents and restricted cash at end of period	10,055	3,730	2,748
Supplemental Disclosure of Cash Paid for Interest	761	481	376
Non-Cash Transactions:
Right-of-use assets acquired under operating leases	1,077	464	1,041
Flight and ground equipment acquired under finance leases	381	650	93
Operating leases converted to finance leases	0	190	7
Air traffic
Changes in certain assets and liabilities:
Liabilities and deferred revenue	(572)	454	297
Loyalty program
Changes in certain assets and liabilities:
Liabilities and deferred revenue	$ 455	$ 87	$ 319

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Change in accounting principle and other	Common Stock	Additional Paid-in Capital	Retained Earnings / (Deficit)	Retained Earnings / (Deficit)Change in accounting principle and other	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive LossChange in accounting principle and other	Treasury Stock
Beginning balance at Dec. 31, 2017	$ 12,530	$ (260)	$ 0	$ 12,053	$ 8,256	$ (154)	$ (7,621)	$ (106)	$ (158)
Beginning balance (shares) at Dec. 31, 2017			715						7
Consolidated Statements of Stockholders' Equity
Net (loss)/income	3,935				3,935
Dividends declared	(909)				(909)
Other comprehensive loss	(98)						(98)
Common stock issued for employee equity awards and other	51			91					$ (40)
Common stock issued for employee equity awards and other (shares)			1						1	[1]
Stock options exercised	13			13
Stock options exercised (shares)			1
Stock purchased and retired	(1,575)			(486)	(1,089)
Stock purchased and retired (shares)			(29)
Ending balance at Dec. 31, 2018	13,687		$ 0	11,671	10,039		(7,825)		$ (198)
Ending balance (shares) at Dec. 31, 2018			688						8
Consolidated Statements of Stockholders' Equity
Net (loss)/income	4,767				4,767
Dividends declared	(981)				(981)
Other comprehensive loss	(164)						(164)
Common stock issued for employee equity awards and other	76			114					$ (38)
Common stock issued for employee equity awards and other (shares)			2						1	[1]
Stock purchased and retired	(2,027)			(656)	(1,371)
Stock purchased and retired (shares)			(38)
Ending balance at Dec. 31, 2019	15,358		$ 0	11,129	12,454		(7,989)		$ (236)
Ending balance (shares) at Dec. 31, 2019			652						9
Consolidated Statements of Stockholders' Equity
Net (loss)/income	(12,385)				(12,385)
Dividends declared	(257)				(257)
Other comprehensive loss	(1,049)						(1,049)
Common stock issued for employee equity awards and other	97			120					$ (23)
Common stock issued for employee equity awards and other (shares)			1						0	[1]
Stock purchased and retired	(344)			(104)	(240)
Stock purchased and retired (shares)			(6)
Government support warrant issuance	114			114
Ending balance at Dec. 31, 2020	$ 1,534		$ 0	$ 11,259	$ (428)		$ (9,038)		$ (259)
Ending balance (shares) at Dec. 31, 2020			647						9
[1]	Treasury shares were withheld for payment of taxes, at a weighted average price per share of $52.17, $50.20 and $54.90 in 2020, 2019 and 2018, respectively.

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Treasury shares withheld for payment of taxes, weighted average price per share (usd per share)	[1]	$ 52.17	$ 50.20	$ 54.90
[1]	Treasury shares were withheld for payment of taxes, at a weighted average price per share of $52.17, $50.20 and $54.90 in 2020, 2019 and 2018, respectively.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation Delta Air Lines, Inc., a Delaware corporation, provides scheduled air transportation for passengers and cargo throughout the United States ("U.S.") and around the world. Our Consolidated Financial Statements include the accounts of Delta Air Lines, Inc. and our consolidated subsidiaries and have been prepared in accordance with accounting principles generally accepted in the U.S. ("GAAP"). We are the primary beneficiary of, and have a controlling financial interest in, certain immaterial entities in which we have voting rights of 50% or less, which we consolidate in our financial results. We have marketing alliances with other airlines to enhance our access to domestic and international markets. These arrangements may include codesharing, reciprocal loyalty program benefits, shared or reciprocal access to passenger lounges, joint promotions, common use of airport gates and ticket counters, ticket office co-location and other marketing agreements. We have received antitrust immunity for certain marketing arrangements, which enables us to offer a more integrated route network and develop common sales, marketing and discount programs for customers. Some of our marketing arrangements provide for the sharing of revenues and expenses. Revenues and expenses associated with collaborative arrangements are presented on a gross basis in the applicable line items on our Consolidated Statements of Operations ("income statement"). We have reclassified certain prior period amounts to conform to the current period presentation. Unless otherwise noted, all amounts disclosed are stated before consideration of income taxes. Use of Estimates We are required to make estimates and assumptions when preparing our Consolidated Financial Statements in accordance with GAAP. These estimates and assumptions affect the amounts reported in our Consolidated Financial Statements and the accompanying notes. Actual results could differ materially from those estimates. Recent Accounting Standards Credit Losses. In 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-13, "Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments." Under this ASU, an entity is required to utilize an "expected credit loss model" on certain financial instruments, including trade and financing receivables. This model requires consideration of a broader range of reasonable and supportable information and requires an entity to estimate expected credit losses over the lifetime of the asset. We adopted this standard effective January 1, 2020 and due to the COVID-19 pandemic, we recorded reserves on certain receivables, which are discussed further in Note 5, "Investments." Income Taxes. In 2019, the FASB issued ASU No. 2019-12, "Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes." This standard simplifies the accounting and disclosure requirements for income taxes by clarifying existing guidance to improve consistency in application of ASC 740. This standard also removed the requirement to calculate income tax expense for the stand-alone financial statements of wholly owned subsidiaries. We adopted the new standard effective January 1, 2020 with no impact on our Consolidated Financial Statements. Significant Accounting Policies Our significant accounting policies are disclosed below or included within the topic-specific notes included herein. Cash and Cash Equivalents and Short-Term Investments Short-term, highly liquid investments with maturities of three months or less when purchased are classified as cash and cash equivalents. Investments with maturities of greater than three months, but not in excess of one year, when purchased are classified as short-term investments. Investments with maturities beyond one year when purchased may be classified as short-term investments if they are expected to be available to support our short-term liquidity needs. Our short-term investments were classified as fair value investments and gains and losses were recorded in non-operating expense. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the Consolidated Balance Sheets ("balance sheets") that sum to the total of the same such amounts shown within the Consolidated Statements of Cash Flows ("cash flows statement"). Reconciliation of cash, cash equivalents and restricted cash Year Ended December 31, (in millions) 2020 2019 2018 Current assets: Cash and cash equivalents $ 8,307 $ 2,882 $ 1,565 Restricted cash included in prepaid expenses and other 192 212 47 Noncurrent assets: Cash restricted for airport construction 1,556 636 1,136 Total cash, cash equivalents and restricted cash $ 10,055 $ 3,730 $ 2,748 Inventories Fuel. As part of our strategy to mitigate the cost of the refining margin reflected in the price of jet fuel, our wholly owned subsidiaries, Monroe Energy, LLC and MIPC, LLC (collectively, "Monroe"), operate the Trainer oil refinery. Refined product, feedstock and blendstock inventories, all of which are finished goods, are carried at recoverable cost. We use jet fuel in our airline operations that is produced by the refinery and procured through the exchange with third parties of gasoline, diesel and other refined products ("non-jet fuel products") the refinery produces. Cost is determined using the first-in, first-out method. Costs include the raw material consumed plus direct manufacturing costs (such as labor, utilities and supplies) incurred and an applicable portion of manufacturing overhead. Expendables Parts and Supplies. Inventories of expendable parts related to flight equipment, which cannot be economically repaired, reconditioned or reused after removal from the aircraft, are carried at moving average cost and charged to operations as consumed. An allowance for obsolescence is provided over the remaining useful life of the related fleet. We also provide allowances for parts identified as excess or obsolete to reduce the carrying costs to the lower of cost or net realizable value. These parts are assumed to have an estimated residual value of 5% of the original cost. Accounting for Refinery Related Buy/Sell Agreements To the extent that we receive jet fuel for non-jet fuel products exchanged under buy/sell agreements, we account for these transactions as nonmonetary exchanges. We have recorded these nonmonetary exchanges at the carrying amount of the non-jet fuel products transferred within aircraft fuel and related taxes on the income statement. Derivatives Changes in fuel prices, interest rates and foreign currency exchange rates impact our results of operations. In an effort to manage our exposure to these risks, we may enter into derivative contracts and adjust our derivative portfolio as market conditions change. We recognize derivative contracts at fair value on our balance sheets. The following table summarizes the risk hedged and the classification of related gains and losses in our income statement, by each type of derivative contract: Derivative Type Hedged Risk Classification of Gains and Losses Fuel hedge contracts Fluctuations in fuel prices Aircraft fuel and related taxes Interest rate contracts Increases in interest rates Interest expense, net Foreign currency exchange contracts Fluctuations in foreign currency exchange rates Non-operating expense The following table summarizes the accounting treatment of our derivative contracts: Accounting Designation Impact of Unrealized Gains and Losses Not designated as hedges Change in fair value (1) of hedge is recorded in earnings Designated as cash flow hedges Market adjustments are recorded in Accumulated Other Comprehensive Income ("AOCI") Designated as fair value hedges Market adjustments are recorded in debt and finance leases (1) Including settled gains and losses as well as mark-to-market adjustments ("MTM adjustments"). We perform, at least quarterly, an assessment of the effectiveness of our derivative contracts designated as hedges, including assessing the possibility of counterparty default. If we determine that a derivative is no longer expected to be highly effective, we discontinue hedge accounting prospectively and recognize subsequent changes in the fair value of the hedge in earnings. We believe our derivative contracts that continue to be designated as hedges, consisting of interest rate exchange contracts, will continue to be highly effective in offsetting changes in fair value attributable to the hedged risk. Cash flows associated with purchasing and settling hedge contracts generally are classified as operating cash flows. However, if a hedge contract includes a significant financing element at inception, cash flows associated with the hedge contract are recorded as financing cash flows. Hedge Margin. The hedge margin we receive from counterparties is recorded in cash, with the offsetting obligation in accounts payable. The hedge margin we provide to counterparties is recorded in prepaid expenses and other. We do not offset margin funded to counterparties or margin funded to us by counterparties against fair value amounts recorded for our hedge contracts. Property and Equipment, net Our flight equipment, which consists of aircraft and associated engines and parts, and other long-lived assets, which are classified as property and equipment, net on our balance sheet, have a recorded value of $26.5 billion at December 31, 2020. The following table summarizes our property and equipment: Property and equipment by classification December 31, (in millions, except for estimated useful life) Estimated Useful Life 2020 2019 Flight equipment 20-34 years $ 31,572 $ 36,713 Ground property and equipment 3-40 years 6,387 5,721 Information technology-related assets 3-15 years 3,403 3,276 Flight and ground equipment under finance leases Shorter of lease term or estimated useful life 1,795 1,608 Advance payments for equipment 883 1,019 Less: accumulated depreciation and amortization (1) (17,511) (17,027) Total property and equipment, net $ 26,529 $ 31,310 (1) Includes accumulated amortization for flight and ground equipment under finance leases in the amount of $793 million and $546 million at December 31, 2020 and 2019, respectively. We record property and equipment at cost and depreciate or amortize these assets on a straight-line basis to their estimated residual values over their estimated useful lives. The estimated useful life for leasehold improvements is the shorter of lease term or estimated useful life. Depreciation and amortization expense related to our property and equipment was $2.3 billion, $2.6 billion and $2.3 billion for the years ended December 31, 2020, 2019 and 2018, respectively. Residual values for owned aircraft, engines, spare parts and simulators are generally 5% to 10% of cost. We capitalize certain internal and external costs incurred to develop and implement software and amortize those costs over an estimated useful life of three ten Our tangible assets consist primarily of flight equipment, which is mobile across geographic markets. Accordingly, assets are not allocated to specific geographic regions. We review flight equipment and other long-lived assets used in operations for impairment losses when events and circumstances indicate the assets may be impaired. Factors which could be indicators of impairment include, but are not limited to (1) a decision to permanently remove flight equipment or other long-lived assets from operations, (2) significant changes in the estimated useful life, (3) significant changes in projected cash flows, (4) permanent and significant declines in fleet fair values and (5) changes to the regulatory environment. For long-lived assets held for sale, we discontinue depreciation and record impairment losses when the carrying amount of these assets is greater than the fair value less the cost to sell. See Note 2, "Impact of the COVID-19 Pandemic," for information on impairments and related charges recorded during 2020. To determine whether impairments exist for active and temporarily parked aircraft, we group assets at the fleet type level or at the contract level for aircraft operated by third-party regional carriers (i.e., the lowest level for which there are identifiable cash flows) and then estimate future cash flows based on projections of capacity, passenger mile yield, fuel and labor costs and other relevant factors. Given the substantial reduction in our active aircraft and diminished projections of future cash flows in the near term as a result of the COVID-19 pandemic, we evaluated our fleet during 2020 and determined that only the fleet types discussed in Note 2, "Impact of the COVID-19 Pandemic," were impaired, as the future cash flows from the operation of all other fleet types through the respective retirement dates exceeded the carrying value. As we obtain greater clarity about the duration and extent of reduced demand and potentially execute further capacity adjustments, we will continue to evaluate our fleet compared to network requirements and may decide to retire additional aircraft. Future decisions regarding the temporarily parked aircraft and the timing of any return to service will be dependent on the evolution of the demand environment. Income Taxes We account for deferred income taxes under the liability method. We recognize deferred tax assets and liabilities based on the tax effects of temporary differences between the financial statement and tax basis of assets and liabilities, as measured by current enacted tax rates. Deferred tax assets and liabilities are net by jurisdiction and are recorded as noncurrent on the balance sheet. We have elected to recognize earnings of foreign affiliates that are determined to be global intangible low tax income in the period it arises and do not recognize deferred taxes for basis differences that may reverse in future years. A valuation allowance is recorded to reduce deferred tax assets when necessary. We periodically assess whether it is more likely than not that we will generate sufficient taxable income to realize our deferred income tax assets. We establish valuation allowances if it is not likely we will realize our deferred income tax assets. In making this determination, we consider available positive and negative evidence and make certain assumptions. We consider, among other things, projected future taxable income, scheduled reversals of deferred tax liabilities, the overall business environment, our historical financial results and tax planning strategies. See Note 13, "Income Taxes," for further information on our deferred income taxes. Fuel Card Obligation We have a purchasing card with American Express for the purpose of buying jet fuel and crude oil. The card carried a maximum credit limit of $1.1 billion as of December 31, 2020 and must be paid monthly. At December 31, 2020 and 2019, we had $1.1 billion and $736 million outstanding on this purchasing card, respectively, and the activity was classified as a financing activity in our cash flows statement. Retirement of Repurchased Shares We immediately retire shares repurchased pursuant to any share repurchase program. We allocate the share purchase price in excess of par value between additional paid-in capital and retained earnings. Manufacturers' Credits We periodically receive credits in connection with the acquisition of aircraft and engines. These credits are deferred until the aircraft and engines are delivered, and then applied as a reduction to the cost of the related equipment. Maintenance Costs We record maintenance costs related to our fleet in aircraft maintenance materials and outside repairs. Maintenance costs are expensed as incurred, except for costs incurred under power-by-the-hour contracts, which are expensed based on actual hours flown. Power-by-the-hour contracts transfer certain risk to third-party service providers and fix the amount we pay per flight hour to the service provider in exchange for maintenance and repairs under a predefined maintenance program. Modifications that enhance the operating performance or extend the useful lives of airframes or engines are capitalized and amortized over the remaining estimated useful life of the asset or the remaining lease term, whichever is shorter. Advertising Costs We expense advertising costs in passenger commissions and other selling expenses in the year the advertising first takes place. Advertising expense was $119 million, $288 million and $267 million for the years ended December 31, 2020, 2019 and 2018, respectively. Commissions and Merchant Fees Passenger sales commissions and merchant fees are recognized in operating expense when the related revenue is recognized.

Impact of the COVID-19 Pandemic

Impact of the COVID-19 Pandemic	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Impact of the COVID-19 Pandemic	IMPACT OF THE COVID-19 PANDEMIC The unprecedented, widespread and persistent impact of COVID-19 and the related travel restrictions and social distancing measures implemented throughout the world have significantly reduced demand for air travel. After initially impacting our service to China beginning in January 2020, the spread of the virus and the resulting global pandemic have significantly affected our entire network. Beginning in March 2020, large public events were cancelled, governmental authorities began imposing restrictions on non-essential activities, businesses suspended travel and popular leisure destinations temporarily closed to visitors. Certain countries that are key markets for our business have imposed bans on international travelers for specified periods or indefinitely. As a result, demand for travel declined at a rapid pace in the March 2020 quarter and has remained depressed, which has had an unprecedented and materially adverse impact on our results of operations and financial position. Although demand has improved at a slow pace since that time, it remains significantly below pre-pandemic levels. The exact timing and pace of the recovery remain uncertain as certain markets have reopened, some of which have since experienced a resurgence of COVID-19 cases, while others, particularly international markets, remain closed or are enforcing extended quarantines for most U.S. residents. The U.S. and numerous other countries are now also requiring airline passengers to provide negative COVID-19 test results prior to travel into their countries. Additionally, some states have instituted travel restrictions, advisories or quarantines for travelers from other states within the U.S. We expect the demand environment to remain depressed until effective vaccines become broadly available, vaccination becomes widespread globally and travel restrictions and advisories begin to ease. Our forecasted expense and liquidity management initiatives may be modified as the demand environment evolves. In response to these developments, we have implemented enhanced measures focusing on the safety of our customers and employees, while at the same time seeking to mitigate the impact on our financial position and operations and to position our business for recovery. Taking Care of our Customers and Employees. The safety of our customers and employees is our primary focus. As the COVID-19 pandemic has progressed, we have taken numerous steps to help promote the safety of our customers and employees on the ground and in the air in keeping with current health-expert recommendations, including: • Adopting new cleaning procedures on all flights, including regular disinfectant electrostatic spraying on aircraft and sanitizing high-touch areas like tray tables, entertainment screens, armrests and seat-back pockets. • Taking steps to help employees and customers practice social distancing and promote safety, including: ◦ Creating a Global Cleanliness Division to ensure a consistently safe and sanitized experience across our facilities and aircraft. ◦ Beginning in May 2020, requiring all customers and customer-facing employees to wear masks. ◦ Capping load factors throughout our aircraft and blocking middle seats through at least April 30, 2021. ◦ Modifying our boarding and deplaning processes, while providing limited food and beverage service that is designed to reduce physical touch points. ◦ Encouraging social distancing throughout all aspects of our operation. ◦ Implementing significant workforce social distancing and protection measures, including reconfiguring call center spaces to promote social distancing, increasing cleaning and disinfecting of our facilities and encouraging employees to work remotely when possible. • Giving customers flexibility to plan and re-book travel, including extending expiration on certain tickets and travel credits through December 2022, eliminating change fees for domestic tickets and international tickets originating from North America, with the exception of Basic Economy tickets, and waiving change fees for all tickets purchased before March 30, 2021. Additionally, we are extending 2020 Medallion Status an additional year, rolling Medallion Qualification Miles into 2021 and extending Delta SkyMiles American Express Card benefits and Delta Sky Club memberships. • Offering pay protection to employees who have tested positive for COVID-19, who must quarantine due to exposure to COVID-19, who are considered being at high-risk for illness from COVID-19 according to the Centers for Disease Control and Prevention ("CDC") guidelines and do not have the ability to work remotely. • Offering on-site rapid COVID-19 testing in most locations and making at-home testing available for all U.S.-based employees. We have also added rapid testing in most U.S. hubs for active flight crews. Capacity Reductions. Beginning in the second half of March 2020, we experienced a precipitous decrease in demand as COVID-19 spread throughout the world. While we have increased capacity compared to the lowest levels in April 2020, system capacity remains significantly lower than prior to the COVID-19 pandemic. During 2020, system capacity was reduced approximately 50% compared to 2019, with international capacity reduced by approximately 65% and domestic capacity reduced by approximately 45%. System capacity for the March 2020 through December 2020 period, excluding the pre-pandemic months of January and February, was reduced by approximately 60%, with international capacity reduced by approximately 75% and domestic capacity reduced by approximately 50%. For the March 2021 quarter, system capacity is expected to be down approximately 30-40% compared to the March 2019 quarter. As a result of reduced demand and lower capacity, we retired 227 aircraft in 2020 and have temporarily parked approximately 125 aircraft as of December 31, 2020. Expense Management. In response to the reduction in revenue, we have implemented, and will continue to implement, cost saving initiatives, including the following in 2020: • Reducing capacity as described above to align with expected demand, which has resulted in removing from active service approximately 350 aircraft as of December 31, 2020, including certain fleets or aircraft that we have decided to early retire as described below. • Consolidating our footprint at our airport facilities, including temporarily closing some Delta Sky Clubs. • Avoiding furloughs for our U.S. employees and reducing employee-related costs, through the following: ◦ Voluntary unpaid leaves of 30 days to 12 months offered to most employees. Approximately 50,000 of our employees have taken or have elected to take voluntary leaves at various times during 2020 and, for those taking leaves up to 12 months, continuing through 2021. ◦ Offering employees early retirement and voluntary separation programs, with approximately 18,000 employees electing to participate. See Note 11, "Employee Benefit Plans," for additional information. ◦ Reaching an agreement with ALPA that protects our pilots from furlough through April 2022. ◦ From April 1 through December 31, 2020, salary reductions of 100% for our CEO, 50% for our officers and a 25% reduction in work hours for all other management and most front-line employee work groups. • Delaying or eliminating nearly all other discretionary spending. Balance Sheet, Cash Flow and Liquidity. Our cash, cash equivalents, short-term investments and aggregate principal amount committed and available to be drawn under our revolving credit facilities ("liquidity") as of December 31, 2020 was $16.7 billion as a result of the following actions to increase liquidity and strengthen our financial position during the year ended December 31, 2020: • Completing financing transactions for an aggregate principal amount of approximately $25.9 billion. • Receiving $5.6 billion as part of the CARES Act payroll support program as described in "Government Support Programs" below. • Reducing planned capital expenditures by approximately $2.8 billion for the year to $1.9 billion, including restructuring our aircraft order books for future aircraft deliveries, delaying aircraft modifications and postponing certain information technology initiatives and ground equipment replacement. See Note 12, "Commitments and Contingencies," for additional information about our aircraft purchase commitments. • Amending our credit facilities to replace fixed charge coverage ratio covenants with liquidity-based covenants. • Suspending share repurchases and dividends indefinitely and postponing voluntary pension funding. In addition, in January 2021 we received $1.4 billion with respect to the payroll support program extension described below, with the remaining $1.5 billion expected in the March 2021 quarter. In response to the impact that the demand environment has had on our financial condition, our credit rating was downgraded by Standard & Poor's to BB in March 2020 and by Fitch to BB+ in April 2020. Our credit rating from Moody's remains Baa3. See "Financial Condition and Liquidity - Sources and Uses of Liquidity" for additional information. See Note 8, "Debt," and Note 9, "Leases," for more information on our financing activities during the year ended December 31, 2020. Government Support Programs On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act ("CARES Act") was enacted into law. The CARES Act is a support package intended to assist many aspects of the American economy, including providing the airline industry with up to $25 billion in grants and loans to be used for employee wages, salaries and benefits. In April 2020, we entered into an agreement with the U.S. Department of the Treasury to receive emergency support through the CARES Act payroll support program, which totaled $5.6 billion. The support payments were conditioned on our agreement to comply with a variety of conditions, including to refrain from conducting involuntary employee layoffs or furloughs through September 30, 2020. The support payments consisted of $4.0 billion in a grant and $1.6 billion in an unsecured 10-year low interest loan. The loan bears interest at an annual rate of 1.00% for the first five years (through April 2025) and the Secured Overnight Financing Rate ("SOFR") plus 2.00% in the final five years. In return, we issued to the U.S. Department of the Treasury warrants to acquire more than 6.7 million shares of Delta common stock, which represented approximately 1% of our outstanding shares. These warrants have an initial exercise price of $24.39 per share, subject to adjustment in certain cases, and a five-year term. The relative fair value of the warrants issued in 2020 is recorded within stockholder's equity and as a discount reducing the carrying value of the loan which is being amortized as interest expense in our income statement over the term of the loan. The proceeds of the 2020 CARES Act grant were recorded in cash and cash equivalents when received and were recognized as contra-expense in government grant recognition in our income statement over the periods that the funds were intended to compensate. See Note 8 "Debt," for further discussion of the unsecured loan and warrants to acquire Delta shares issued under the CARES Act payroll support program. Finally, the CARES Act also provides for deferred payment of the employer portion of social security taxes through the end of 2020, with 50% of the deferred amount due December 31, 2021 and the remaining 50% due December 31, 2022. This provided us with approximately $200 million of additional liquidity during 2020. On December 27, 2020, an additional COVID-19 support bill was enacted into law, which extends the payroll support program of the CARES Act and provides an additional $15 billion in grants and loans to be used for airline employee wages, salaries and benefits. In January 2021, we entered into a payroll support program extension agreement with the U.S. Department of the Treasury. We expect to receive $2.9 billion in payroll support payments, which must be used exclusively for the payment of employee wages, salaries and benefits and are conditioned on our agreement to refrain from conducting involuntary employee layoffs or furloughs from the date of the extension agreement through March 2021. Other conditions include prohibitions on share repurchases and dividends through March 2022 and certain limitations on executive compensation until October 2022. The Department of Transportation also has the authority until March 1, 2022 to require airlines that received payroll support program funds to maintain scheduled air service deemed necessary to any point served by the airline before March 1, 2020. The expected support payments consist of approximately $2.0 billion in grants and $830 million in an unsecured 10-year low interest loan. We received the first installment of $1.4 billion under the agreement on January 15, 2021 and expect to receive the balance in the March 2021 quarter. The loan bears interest at an annual rate of 1.00% for the first five years (through January 15, 2026) and the applicable SOFR plus 2.00% in the final five years. Approximately 70% of the payment received on January 15, 2021 was in the form of a grant, and approximately 30% was in the form of an unsecured loan. We issued a promissory note for approximately $400 million with respect to the term loan, which will increase to its full principal amount as the balance of payroll support payments is received. In connection with receipt of these payments, we also expect to issue to the U.S. Department of the Treasury warrants to acquire shares of Delta common stock, which we expect to be approximately 2.1 million shares representing less than 0.5% of our outstanding shares. Approximately one-half of the expected warrants were issued on January 15, 2021 and the remaining warrants will be issued as the balance of payroll support payments is received. These warrants have an initial exercise price of $39.73 per share, subject to adjustment in certain cases, and a five-year term. Restructuring Charges The restructuring charges incurred during 2020 as part of our response to the COVID-19 pandemic are summarized as follows: Restructuring charges by category (in millions) Year Ended Fleet Retirements $ 4,409 Voluntary Programs and Other Employee Benefit Charges 3,409 Receivables and Other 401 Total Restructuring Charges $ 8,219 Fleet Retirements. As a result of the COVID-19 pandemic and our response, we have removed certain aircraft from active service as of December 31, 2020, which includes owned and leased aircraft that are being retired early. Fleet retirements by aircraft type Fleet Type Number of Aircraft Estimated Final Retirement During the Quarter Ended Impairment-Related Charge (in millions) 777 18 December 2020 $ 1,440 767-300ER 56 December 2025 1,084 717 91 December 2025 950 MD-90 26 June 2020 335 CRJ-200 (1) 125 December 2023 320 737-700 10 September 2020 223 A320 10 June 2020 57 MD-88 (2) 47 June 2020 — Total 383 $ 4,409 (1) Certain of the CRJ-200 aircraft scheduled to be retired by the December 2023 quarter are operated for us by SkyWest Airlines under a revenue proration agreement. (2) During the March 2020 quarter, we recorded a $22 million charge related to accelerating the planned retirement of the MD-88 fleet from December 2020 to June 2020. However, this amount was recorded in depreciation and amortization, rather than in restructuring charges, as it would have been incurred during 2020 prior to the onset of the COVID-19 pandemic. These impairment and other related charges are recorded in restructuring charges in our income statement. These charges were calculated using Level 3 fair value inputs based primarily upon recent market transactions and third-party bids, which were corroborated with published pricing guides and our assessment of existing market conditions based on industry knowledge. Following the impairment charges, the remaining aggregate net book value of these aircraft as of December 31, 2020 is approximately $500 million. Voluntary Programs and Other Employee Benefit Charges. See Note 11, "Employee Benefit Plans," for further information on these charges. Receivables and Other. See Note 5, "Investments," for further information on certain of these charges.

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue Recognition	REVENUE RECOGNITION Passenger Revenue Passenger revenue is primarily composed of passenger ticket sales, loyalty travel awards and travel-related services performed in conjunction with a passenger’s flight. Passenger revenue by category Year Ended December 31, (in millions) 2020 2019 2018 Ticket $ 10,970 $ 36,908 $ 34,950 Loyalty travel awards 935 2,900 2,651 Travel-related services 978 2,469 2,154 Total passenger revenue $ 12,883 $ 42,277 $ 39,755 Ticket Passenger Tickets. We defer sales of passenger tickets to be flown by us or that we sell on behalf of other airlines in our air traffic liability. Passenger revenue is recognized when we provide transportation or when ticket breakage occurs. For tickets that we sell on behalf of other airlines, we reduce the air traffic liability when consideration is remitted to those airlines. The air traffic liability primarily includes sales of passenger tickets to be flown in the future and credits which can be applied as payment toward the cost of a ticket ("travel credits"). Travel credits are typically issued as a result of ticket cancellations prior to their expiration dates. We periodically evaluate the estimated air traffic liability and record any adjustments in our income statement. These adjustments relate primarily to refunds, exchanges, ticket breakage, transactions with other airlines and other items for which final settlement occurs in periods subsequent to the sale of the related tickets at amounts other than the original sales price. The air traffic liability typically increases during the winter and spring months as advanced ticket sales grow prior to the summer peak travel season and decreases during the summer and fall months. However, the ongoing reduction in demand for air travel due to the COVID-19 pandemic has resulted in an unprecedented low level of advance bookings and the associated cash received, as well as significant ticket cancellations which led to issuance of cash refunds or travel credits to customers. The total value of cash refunds, excluding taxes and related fees, issued to customers during 2020 was approximately $3.1 billion. Travel credits represented approximately 65% of the air traffic liability as of December 31, 2020. Prior to April 2020, passenger tickets sold and credits issued were generally valid for one year from the date of original ticket issuance . During 2020, we announced the extension of expiration on certain tickets and travel credits through December 2022. The air traffic liability classified as noncurrent as of December 31, 2020 represents our current estimate of tickets and credits to be used or refunded beyond one year, while the balance classified as current represents our current estimate of tickets and credits to be used or refunded within one year. We will continue to monitor our customers' travel behavior and may adjust our estimates in the future. Approximately $3.1 billion, $3.8 billion and $3.5 billion of the prior year air traffic liability related to passenger ticket sales (which excludes those tickets sold on behalf of other airlines) was recognized in passenger revenue during the years ended December 31, 2020, 2019 and 2018, respectively. Ticket Breakage. We estimate the value of tickets that will expire unused and recognize revenue at the scheduled flight date. We periodically evaluate our breakage estimates, which are based on historical experience, ticket contract terms and customers’ travel behavior, and may adjust our estimates in the future. Regional Carriers . Our regional carriers include both third-party regional carriers with which we have contract carrier agreements ("contract carriers") and Endeavor Air, Inc., our wholly owned subsidiary. Our contract carrier agreements are primarily structured as capacity purchase agreements where we purchase all or a portion of the contract carrier's capacity and are responsible for selling the seat inventory we purchase. We record revenue related to our capacity purchase agreements in passenger revenue and the related expenses in regional carriers expense, excluding fuel. Loyalty Travel Awards Loyalty travel awards revenue is related to the redemption of miles for travel. We recognize loyalty travel awards revenue in passenger revenue as miles are redeemed and transportation is provided. See below for discussion of our loyalty program accounting policies. Travel-Related Services Travel-related services are primarily composed of services performed in conjunction with a passenger’s flight, including administrative fees (such as ticket change fees), baggage fees and on-board sales. We recognize revenue for these services when the related transportation service is provided. During 2020, we waived change fees for all tickets purchased through March 30, 2021 and eliminated change fees for domestic tickets and international tickets originating from North America, with the exception of Basic Economy tickets. Loyalty Program Our SkyMiles loyalty program generates customer loyalty by rewarding customers with incentives to travel on Delta. This program allows customers to earn mileage credits ("miles") by flying on Delta, Delta Connection and other airlines that participate in the loyalty program. When traveling, customers earn miles based on the passenger's loyalty program status and ticket price. Customers can also earn miles through participating companies such as credit card companies, hotels, car rental agencies and ridesharing companies. Miles are redeemable by customers in future periods for air travel on Delta and other participating airlines, membership in our Sky Club and other program awards. To facilitate transactions with participating companies, we sell miles to non-airline businesses, customers and other airlines. The loyalty program includes two types of transactions that are considered revenue arrangements with multiple performance obligations (1) passenger ticket sales earning miles and (2) sale of miles to participating companies. Passenger Ticket Sales Earning Miles. Passenger ticket sales earning miles provide customers with (1) miles earned and (2) air transportation, which are each considered performance obligations. We value each performance obligation on a standalone basis. To value the miles earned, we consider the quantitative value a passenger receives by redeeming miles for a ticket rather than paying cash, which is referred to as equivalent ticket value ("ETV"). Our estimate of ETV is adjusted for miles that are not likely to be redeemed ("breakage"). We use statistical models to estimate breakage based on historical redemption patterns. A change in assumptions to the redemption activity for miles or the estimated fair value of miles expected to be redeemed could have a material impact on our revenue in the year in which the change occurs and in future years. We recognize breakage proportionally during the period in which the remaining miles are actually redeemed. We defer revenue for the miles when earned and recognize loyalty travel awards in passenger revenue as the miles are redeemed and transportation is provided. We record the air transportation portion of the passenger ticket sales in air traffic liability and recognize passenger revenue when we provide transportation or if the ticket goes unused. Sale of Miles to Participating Companies. Customers earn miles based on their spending with participating companies such as credit card companies, hotels, car rental agencies and ridesharing companies with which we have marketing agreements to sell miles. Our contracts to sell miles under these marketing agreements have multiple performance obligations. Payments are typically due to us monthly based on the volume of miles sold during the period, and the initial terms of our marketing contracts are from three eleven Our most significant contract to sell miles relates to our co-brand credit card relationship with American Express. Our agreements with American Express provide for joint marketing, grant certain benefits to Delta-American Express co-branded credit card holders ("cardholders") and American Express Membership Rewards program participants, and allow American Express to market its services or products using our customer database. Cardholders earn miles for making purchases using co-branded cards, and certain cardholders may also check their first bag for free, are granted discounted access to Delta Sky Club lounges and receive priority boarding and other benefits while traveling on Delta. Additionally, participants in the American Express Membership Rewards program may exchange their points for miles under the loyalty program. We sell miles at agreed-upon rates to American Express which are then provided to their customers under the co-brand credit card program and the Membership Rewards program. Effective January 1, 2019, we amended our co-brand and other agreements with American Express which increased the value we receive and extended the terms to 2029. The products and services delivered are consistent with previous agreements. We account for marketing agreements, including those with American Express, by allocating the consideration received to the individual products and services delivered. We allocate the value based on the relative selling prices of those products and services, which generally consist of award travel, priority boarding, baggage fee waivers, lounge access and the use of our brand. We determine our best estimate of the selling prices by using a discounted cash flow analysis using multiple inputs and assumptions, including (1) the expected number of miles awarded and number of miles redeemed, (2) ETV for the award travel obligation adjusted for breakage, (3) published rates on our website for baggage fees, discounted access to Delta Sky Club lounges and other benefits while traveling on Delta, (4) brand value (using estimated royalties generated from the use of our brand) and (5) volume discounts provided to certain partners. We defer the amount allocated to award travel as part of loyalty program deferred revenue and recognize loyalty travel awards in passenger revenue as the miles are redeemed and transportation is provided. Revenue allocated to services performed in conjunction with a passenger’s flight, such as baggage fee waivers, is recognized as travel-related services in passenger revenue when the related service is performed. Revenue allocated to access Delta Sky Club lounges is recognized as miscellaneous in other revenue as access is provided. Revenue allocated to the remaining performance obligations, primarily brand value, is recorded as loyalty program in other revenue as miles are delivered. In September 2020, we raised $9.0 billion through the issuance of notes and entry into a term loan facility, each secured by certain assets related to our SkyMiles program. See Note 8, "Debt," for further discussion of these transactions. Current Activity of the Loyalty Program. Miles are combined in one homogeneous pool and are not separately identifiable. Therefore, the revenue is comprised of miles that were part of the loyalty program deferred revenue balance at the beginning of the period as well as miles that were issued during the period. The table below presents the activity of the current and noncurrent loyalty program deferred revenue, and includes miles earned through travel and miles sold to participating companies, which are primarily through marketing agreements. Loyalty program activity (in millions) 2020 2019 2018 Balance at January 1 $ 6,728 $ 6,641 $ 6,321 Miles earned 1,437 3,156 3,142 Travel miles redeemed (935) (2,900) (2,651) Non-travel miles redeemed (48) (169) (171) Balance at December 31 $ 7,182 $ 6,728 $ 6,641 The timing of mile redemptions can vary widely; however, the majority of new miles have historically been redeemed within two years. The loyalty program deferred revenue classified as a current liability represents our current estimate of revenue expected to be recognized in the next twelve months based on projected redemptions, while the balance classified as a noncurrent liability represents our current estimate of revenue expected to be recognized beyond twelve months. As a result of the COVID-19 pandemic, a larger portion of mile redemptions is projected to occur beyond twelve months and is therefore reflected as a noncurrent liability as of December 31, 2020. We will continue to monitor redemptions as the situation evolves. Revenue by Geographic Region Operating revenue for the airline segment is recognized in a specific geographic region based on the origin, flight path and destination of each flight segment. A significant portion of the refinery's revenues typically consists of fuel sales to support the airline, which is eliminated in the Consolidated Financial Statements. The remaining operating revenue for the refinery segment is included in the domestic region. Our passenger and operating revenue by geographic region is summarized in the following table: Revenue by geographic region Passenger Revenue Operating Revenue Year Ended December 31, Year Ended December 31, (in millions) 2020 2019 2018 2020 2019 2018 Domestic $ 10,041 $ 30,465 $ 28,235 $ 13,339 $ 33,382 $ 31,309 Atlantic 1,171 6,326 6,135 1,649 7,308 7,012 Latin America 1,113 2,985 2,864 1,321 3,326 3,157 Pacific 558 2,501 2,521 786 2,991 2,960 Total $ 12,883 $ 42,277 $ 39,755 $ 17,095 $ 47,007 $ 44,438 Cargo Revenue Cargo revenue is recognized when we provide the transportation. Other Revenue Year Ended December 31, (in millions) 2020 2019 2018 Ancillary businesses and refinery $ 1,798 $ 1,297 $ 1,801 Loyalty program 1,458 1,962 1,459 Miscellaneous 348 718 558 Total other revenue $ 3,604 $ 3,977 $ 3,818 Ancillary Businesses and Refinery. Ancillary businesses and refinery includes refinery sales to third parties, aircraft maintenance provided to third parties and our vacation wholesale operations. Third-party refinery production sales are at or near cost; accordingly, the margin on these sales is de minimis. See Note 16, "Segments," for more information on revenue recognition within our refinery segment. In January 2020, we combined Delta Private Jets, our former wholly owned subsidiary which provided private jet operations, with Wheels Up. Upon closing, we received an equity stake in Wheels Up, and Delta Private Jets is no longer reflected in ancillary businesses and refinery. See Note 5, "Investments," for more information on this transaction. Loyalty Program. Loyalty program revenues relate primarily to brand usage by third parties and include the redemption of miles for non-travel awards. These revenues are included within the total cash sales from marketing agreements, discussed above. Miscellaneous. Miscellaneous revenue is primarily composed of lounge access and codeshare revenues. Accounts Receivable Accounts receivable primarily consist of amounts due from credit card companies from the sale of passenger tickets, ancillary businesses and refinery sales and other companies for the purchase of miles under the loyalty program. We provide an allowance for uncollectible accounts using an expected credit loss model which represents our estimate of expected credit losses over the lifetime of the asset. In 2020, due to the COVID-19 pandemic, we recorded reserves on certain receivables, which are discussed further in Note 5, "Investments."

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value is a market-based measurement that is determined based on assumptions that market participants would use in pricing an asset or liability. • Level 1. Observable inputs such as quoted prices in active markets. • Level 2 . Inputs, other than quoted prices in active markets, that are observable either directly or indirectly. • Level 3 . Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. Assets and liabilities measured at fair value are based on the valuation techniques identified in the tables below. The valuation techniques are as follows: (a) Market Approach . Prices and other relevant information generated by observable transactions involving identical or comparable assets or liabilities; and (b) Income Approach. Techniques to convert future amounts to a single present value amount based on market expectations (including present value techniques and option-pricing models). Assets (Liabilities) Measured at Fair Value on a Recurring Basis (1) December 31, 2020 Valuation (in millions) Total Level 1 Level 2 Level 3 Cash equivalents $ 5,755 $ 5,755 $ — $ — (a) Restricted cash equivalents 1,747 1,747 — — (a) Short-term investments U.S. Government securities 5,789 3,919 1,870 — (a) Long-term investments 1,417 948 38 431 (a)(b) Hedge derivatives, net Fuel hedge contracts (9) — (9) — (a)(b) Interest rate contracts 23 — 23 — (a) Foreign currency exchange contracts (13) — (13) — (a) December 31, 2019 Valuation (in millions) Total Level 1 Level 2 Level 3 Cash equivalents $ 586 $ 586 $ — $ — (a) Restricted cash equivalents 847 847 — — (a) Long-term investments 1,099 881 33 185 (a)(b) Hedge derivatives, net Fuel hedge contracts 1 (1) 2 — (a)(b) Interest rate contracts 61 — 61 — (a) Foreign currency exchange contracts 6 — 6 — (a) (1) See Note 11, "Employee Benefit Plans," for fair value of benefit plan assets. Cash Equivalents and Restricted Cash Equivalents. Cash equivalents generally consist of money market funds. Restricted cash equivalents are recorded in prepaid expenses and other and cash restricted for airport construction on our balance sheet and generally consist of money market funds, time deposits, commercial paper and negotiable certificates of deposit, which primarily relate to proceeds from debt issued to finance, among other things, a portion of the construction costs for our new terminal facilities at New York's LaGuardia Airport. The fair value of these cash equivalents is based on a market approach using prices generated by market transactions involving identical or comparable assets. Short-Term Investments. The fair values of our short-term investments are based on a market approach using industry standard valuation techniques that incorporate observable inputs such as quoted market prices, interest rates, benchmark curves, credit ratings of the security or other observable information. Long-Term Investments. Our long-term investments that are measured at fair value primarily consist of equity investments, which are valued based on market prices or other observable transactions and inputs, and are recorded in equity investments on our balance sheet. In addition, our equity investments in private companies (such as the interests we received in Wheels Up during 2020), are classified as Level 3 in the fair value hierarchy as their equity is not traded on a public exchange and our valuations incorporate certain unobservable inputs, including non-public equity issuances and forecasts provided by our investees. Our equity investments in LATAM and Grupo Aeroméxico, which have no remaining value following impairment charges recorded in 2020 due to their entry into bankruptcy proceedings, became classified as Level 3 fair value investments during 2020. Fair value measurement using unobservable inputs is inherently uncertain, and a change in significant inputs could result in different fair values. During the year ended December 31, 2020 there were no material gains or losses as a result of fair value adjustments. See Note 5, "Investments," for further information on our long-term investments. Hedge Derivatives. A portion of our derivative contracts are negotiated over-the-counter with counterparties without going through a public exchange. Accordingly, our fair value assessments give consideration to the risk of counterparty default (as well as our own credit risk). Such contracts are classified as Level 2 within the fair value hierarchy. The remainder of our hedge contracts are comprised of futures contracts, which are traded on a public exchange. These contracts are classified within Level 1 of the fair value hierarchy. • Fuel Hedge Contracts. Our fuel hedge portfolio consists of options, swaps and futures. Option and swap contracts are valued under income approaches using option pricing models and discounted cash flow models, respectively, based on data either readily observable in public markets, derived from public markets or provided by counterparties who regularly trade in public markets. Futures contracts and options on futures contracts are traded on a public exchange and valued based on quoted market prices. • Interest Rate Contracts. Our interest rate derivatives are swap contracts, which are valued based on data readily observable in public markets. • Foreign Currency Exchange Contracts. Our foreign currency derivatives consist of forward contracts and are valued based on data readily observable in public markets.

Investments

Investments	12 Months Ended
	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Investments	INVESTMENTS Short-Term Investments At December 31, 2020, the estimated fair value of our short-term investments was $5.8 billion, which approximates cost. Of these investments, $4.9 billion are expected to mature in one year or less, with the remainder maturing during 2022. Investments with maturities beyond one year when purchased may be classified as short-term investments if they are expected to be available to support our short-term liquidity needs. Long-Term Investments We have developed strategic relationships with a number of airlines and airline services companies through joint ventures and other forms of cooperation and support, including equity investments. Our equity investments reinforce our commitment to these relationships and generally enhance our ability to offer input to the investee on strategic issues and direction, in some cases through representation on the board of directors. LATAM. In January 2020, we acquired 20% of the shares of LATAM for $1.9 billion, or $16 per share, through a tender offer as part of our plan to create a strategic alliance with LATAM. In addition, to support the establishment of the strategic alliance, we agreed to make transition payments to LATAM totaling $350 million, of which $75 million remains to be paid by the end of 2021. As part of our planned strategic alliance with LATAM, we also agreed to acquire four A350 aircraft from LATAM (which agreement has subsequently been terminated, as discussed below) and assumed 10 of LATAM's A350 purchase commitments with Airbus for deliveries through 2025. The total consideration of $2.3 billion, including the tender offer and the transition payments, was allocated in the March 2020 quarter to the shares ($1.1 billion) and to the alliance-related indefinite-lived intangible asset ($1.2 billion) based on their relative fair values. We expect to record the 10 aircraft at cost upon delivery. In May 2020, LATAM filed for bankruptcy under Chapter 11 of the United States bankruptcy code as the result of the impact of the pandemic on its business and, as part of LATAM's reorganization, we terminated the purchase agreement for the four A350 aircraft from LATAM for a fee of $62 million, which was recorded in restructuring charges in our income statement. While our ownership interest remains at 20%, we no longer have significant influence with LATAM during their bankruptcy proceedings and discontinued accounting for the investment under the equity method in the June 2020 quarter and began accounting for the investment at fair value. During the June 2020 quarter, we eliminated the carrying value of our investment in LATAM and recorded expense of $1.1 billion in impairments and equity method losses within non-operating expense in our income statement. This charge reflected the recognition of both our 20% share of LATAM's March 2020 quarter losses (due to the timing of information available from LATAM) and the decline in our expected realizable value for LATAM's shares following its bankruptcy filing. The impairment charge for our investment in LATAM was calculated using Level 3 fair value inputs. During the September 2020 quarter, LATAM’s debtor-in-possession financing was approved by the bankruptcy court to provide LATAM with near-term liquidity and the ability to continue progressing toward a plan of reorganization. We expect that no more than an immaterial amount will be distributed to current equity holders following the settlement of unsecured claims upon LATAM's emergence from bankruptcy. The carrying value of our investment in LATAM remains zero at December 31, 2020. In May 2020, we signed a trans-American joint venture agreement with LATAM that, subject to regulatory approvals, will combine our highly complementary route networks between North and South America, with the goal of providing customers with a seamless travel experience and industry-leading connectivity. In addition, the bankruptcy court has approved the assumption of our strategic partnership agreement, which contributes to supporting the value of our $1.2 billion alliance-related indefinite-lived intangible asset. We believe this alliance will generate growth opportunities, building upon Delta's and LATAM's global footprint and joint ventures. See Note 7, "Goodwill and Intangible Assets," for further discussion of our quantitative impairment assessment of indefinite-lived intangible assets. Grupo Aeroméxico. In June 2020, Grupo Aeroméxico filed for bankruptcy under Chapter 11 of the United States bankruptcy code as the result of the impact of the pandemic on its business. We have a non-controlling 51% ownership interest in Grupo Aeroméxico, however Grupo Aeroméxico's corporate bylaws (as authorized by the Mexican Foreign Investment Commission) limit our voting interest to a maximum of 49%. Therefore, we accounted for our investment under the equity method prior to Grupo Aeroméxico's bankruptcy filing. As a result of Grupo Aeroméxico's bankruptcy filing, while our ownership interest has not changed, we no longer have significant influence with Grupo Aeroméxico during their bankruptcy proceedings and discontinued accounting for the investment under the equity method in the June 2020 quarter and began accounting for the investment at fair value. During the June 2020 quarter, we eliminated the carrying value of our investment in Grupo Aeroméxico and recorded expense of $770 million in impairments and equity method losses within non-operating expense in our income statement. This charge reflected the recognition of both our 51% share of Grupo Aeroméxico's June 2020 quarter losses and the decline in our expected realizable value for Grupo Aeroméxico's shares following its bankruptcy filing. The impairment charge for our investment in Grupo Aeroméxico was calculated using Level 3 fair value inputs. During the December 2020 quarter, Grupo Aeroméxico's debtor-in-possession financing was approved by the bankruptcy court to provide Grupo Aeroméxico with near-term liquidity and the ability to continue progressing toward a plan of reorganization. We expect that no more than an immaterial amount will be distributed to current equity holders following the settlement of unsecured claims upon Grupo Aeroméxico's emergence from bankruptcy. The carrying value of our investment in Grupo Aeroméxico remains zero at December 31, 2020. In addition, we believe Grupo Aeroméxico intends to request the bankruptcy court's approval to assume our joint cooperation agreement. As a result of the significantly decreased demand for air travel caused by the COVID-19 pandemic, LATAM and Grupo Aeroméxico are undergoing in-court restructurings. In order to support our relationships with these carriers, we have provided them with strategic and operational assistance through their restructurings. We recorded notes payable of $165 million, which are recorded in current maturities of debt and finance leases, and receivables from those partners within other noncurrent assets as of December 31, 2020. GOL. In 2019, we sold our ownership stake of GOL Linhas Aéreas Inteligentes, the parent company of GOL Linhas Aéreas (operating as GOL), and have ended our commercial agreements. During 2015, in conjunction with our investment in GOL we agreed to guarantee GOL’s $300 million five Fair Value Investments Our investments accounted for at fair value are summarized in the following table: Fair value investments ownership interest and carrying value Ownership Interest Carrying Value (in millions) December 31, 2020 December 31, 2019 December 31, 2020 December 31, 2019 Hanjin-KAL 13 % 10 % $ 512 $ 205 Air France-KLM 9 % 9 % 235 418 China Eastern 3 % 3 % 201 258 Other investments 469 218 Total fair value investments $ 1,417 $ 1,099 During the year ended December 31, 2020, we recorded net losses on these equity investments of $105 million compared to net gains of $119 million, including a gain from the sale of our ownership stake in GOL, during the year ended December 31, 2019 and $38 million during the year ended December 31, 2018. These results were recorded in gain/(loss) on investments in our income statement within non-operating expense and were driven by changes in stock prices, foreign currency fluctuations and other valuation techniques for investments in companies without publicly-traded shares. Wheels Up. In January 2020, we combined Delta Private Jets, our wholly owned subsidiary which provided private jet operations, with Wheels Up. This transaction resulted in a gain of $240 million which was recorded within miscellaneous, net in our income statement in the March 2020 quarter. Upon closing, we received interests, which represented a 24% equity stake in Wheels Up as of December 31, 2020, included in other investments above. We elected to record our investment using the fair value option as this is expected to better reflect the economics of our ownership interest. In February 2021, Wheels Up entered into a definitive agreement to become publicly-traded via a merger with Aspirational Consumer Lifestyle Corp. The transaction is expected to close in the June 2021 quarter. Equity Method Investments We account for the investments listed below and certain other immaterial investments under the equity method of accounting. Equity method investments ownership interest and carrying value Ownership Interest Carrying Value (in millions) December 31, 2020 December 31, 2019 December 31, 2020 December 31, 2019 Virgin Atlantic (1) 49 % 49 % $ — $ 375 Unifi Aviation 49 % 49 % 154 142 (1) We have a non-controlling equity stake in Virgin Atlantic Limited, the parent company of Virgin Atlantic Airways, and similar non-controlling interests in certain affiliated Virgin Atlantic companies. Our equity method investments are recorded in equity investments on our balance sheet. If an equity method investment experiences a loss in fair value that is determined to be other than temporary, we will reduce our carrying value of the investment to fair value and record the loss in impairments and equity method losses in our income statement . Virgin Atlantic. As a result of the COVID-19 pandemic and the resulting travel restrictions and quarantines, Virgin Atlantic has incurred significant losses during 2020. In recording our 49% share in Virgin Atlantic's results and based on our review of Virgin Atlantic's financial projections, in the June 2020 quarter we reduced the carrying value of our investment to zero. During the September 2020 quarter, Virgin Atlantic undertook a voluntary recapitalization process in the U.K., which was subsequently approved by its creditors, and instituted ancillary proceedings in support of that process in the U.S. Under related agreements, we recognized a note payable of $115 million, which is recorded in current maturities of debt and finance leases, and a corresponding receivable within other noncurrent assets. During the year ended December 31, 2020, we recorded $510 million in impairments and equity method losses within non-operating expense in our income statement. Under the equity method of accounting, we will track our share of Virgin Atlantic's future losses, but we will not reflect our share of their results in our financial statements until such time that our share of their earnings eliminates the losses beyond our carrying value of the investment. We continue to monitor and support Virgin Atlantic's ongoing restructuring efforts. Effective January 2020, we combined our separate transatlantic joint venture agreements with Air France-KLM and Virgin Atlantic into a single three-party transatlantic joint venture. Under the new agreement, certain measurement thresholds were reset from the previous joint venture with Virgin Atlantic, reducing the value we would have received over the original term. In consideration for this reduced value, we entered into a transition agreement with Virgin Atlantic, which would have resulted in payments to us in future periods. However, as of December 31, 2020, based on our assessment of collectability, we do not have any assets or liabilities recorded on our balance sheet related to this transition agreement. Unifi Aviation. We have a 49% ownership interest in AirCo Aviation Services, LLC, which together with its subsidiaries is operating as Unifi Aviation. Our share of Unifi Aviation's financial results is recorded in contracted services in our income statement as this entity is integral to the operations of our business and the services provided by Unifi Aviation are also recorded in contracted services in our income statement. Based on discussions with Unifi Aviation's management and review of their liquidity and financial projections, we do not believe our investment is other than temporarily impaired as we have the intent and ability to retain this investment for a period of time sufficient to allow for anticipated recovery in value. However, we will continue to monitor the continuing effects of the pandemic and self-help measures Unifi Aviation executes. We also have an investment in JFK IAT Member LLC which is accounted for under the equity method and is discussed further in Note 10, "Airport Redevelopment." Receivables from Investees and Other Airlines Based on our assessment of collectability, during the year ended December 31, 2020, we recorded approximately $100 million of reserves against outstanding receivables from LATAM, Grupo Aeroméxico, GOL, Virgin Atlantic, Virgin Australia and others. These reserves reflect our expected recoveries given the impact of the COVID-19 pandemic on our investees and other airlines, and their restructuring efforts or recent bankruptcy filings. In determining the appropriate amount to reserve, we also considered the valuation of and our ability to realize the value of any collateral associated with each receivable. The reserves are recorded within accounts receivable, net or prepaid expenses and other on our balance sheet and within restructuring charges in our income statement.

Derivatives and Risk Management

Derivatives and Risk Management	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Risk Management	DERIVATIVES AND RISK MANAGEMENT Changes in fuel prices, interest rates and foreign currency exchange rates impact our results of operations. In an effort to manage our exposure to these risks, we may enter into derivative contracts and adjust our derivative portfolio as market conditions change. We recognize derivative contracts at fair value on our balance sheets. Cash flows associated with purchasing and settling hedge contracts generally are classified as operating cash flows. Fuel Price Risk Our derivative contracts to hedge the financial risk from changing fuel prices are primarily related to Monroe’s inventory. During the years ended December 31, 2020, 2019 and 2018, fuel hedges did not have a significant impact in our income statement. Interest Rate Risk Our exposure to market risk from adverse changes in interest rates is primarily associated with our debt obligations. Market risk associated with our fixed and variable rate debt relates to the potential reduction in fair value and negative impact to future earnings, respectively, from an increase in interest rates. In an effort to manage our exposure to the risk associated with our variable rate debt, we periodically enter into interest rate swaps. We designate interest rate contracts used to convert the interest rate exposure on a portion of our debt portfolio from a floating rate to a fixed rate as cash flow hedges, while those contracts converting our interest rate exposure from a fixed rate to a floating rate are designated as fair value hedges. We also have exposure to market risk from adverse changes in interest rates associated with our cash and cash equivalents and benefit plan obligations. Market risk associated with our cash and cash equivalents relates to the potential decline in interest income from a decrease in interest rates. Pension, postretirement, postemployment and worker's compensation obligation risk relates to the potential increase in our future obligations and expenses from a decrease in interest rates used to discount these obligations. In the March 2020 quarter, we unwound a majority of our interest rate swap contracts. The unwind of these contracts generated approximately $100 million of cash in the March 2020 quarter. Additionally, in January 2021 we unwound our remaining interest rate swap contract. The unwind of this contract generated approximately $20 million of cash in January 2021. These gains are being reflected in our income statement over the remaining term of the related debt agreements. Foreign Currency Exchange Rate Risk We are subject to foreign currency exchange rate risk because we have revenue, expense and equity investments denominated in foreign currencies. To manage exchange rate risk, we execute both our international revenue and expense transactions in the same foreign currency to the extent practicable. From time to time, we may also enter into foreign currency option and forward contracts. In November 2019, we entered into a three and a half-year U.S. dollar-South Korean won ("KRW") cross currency swap with a notional value of 177 billion KRW. This swap is intended to mitigate foreign currency volatility resulting from our KRW-denominated investment in Hanjin-KAL. During the year ended December 31, 2020, we recorded an unrealized loss on this swap of $10 million, which is reflected in gain/(loss) on investments, net within non-operating expense. Hedge Position as of December 31, 2020 (in millions) Volume Final Maturity Date Prepaid Expenses and Other Other Noncurrent Assets Other Accrued Liabilities Other Noncurrent Liabilities Hedge Derivatives, net Designated as hedges Interest rate contract (fair value hedges) 150 U.S. dollars April 2028 $ 3 $ 20 $ — $ — $ 23 Not designated as hedges Foreign currency exchange contract 177,045 South Korean won April 2023 — — — (13) (13) Fuel hedge contracts 157 gallons - crude oil and refined products April 2021 — — (9) — (9) Total derivative contracts $ 3 $ 20 $ (9) $ (13) $ 1 Hedge Position as of December 31, 2019 (in millions) Volume Final Maturity Date Prepaid Expenses and Other Other Noncurrent Assets Other Accrued Liabilities Other Noncurrent Liabilities Hedge Derivatives, net Designated as hedges Interest rate contracts (fair value hedges) 1,872 U.S. dollars April 2028 $ 12 $ 53 $ (4) $ — $ 61 Not designated as hedges Foreign currency exchange contract 397 Euros December 2020 9 — — — 9 Foreign currency exchange contract 177,045 South Korean won April 2023 1 — — (4) (3) Fuel hedge contracts 243 gallons - crude oil and refined products July 2020 16 — (15) — 1 Total derivative contracts $ 38 $ 53 $ (19) $ (4) $ 68 Balance sheet location of hedged item in fair value hedges Carrying Amount of Hedge Instruments Cumulative Amount of Fair Value Hedge Adjustments (1) (in millions) December 31, 2020 December 31, 2019 December 31, 2020 December 31, 2019 Current maturities of debt and finance leases $ 21 $ (19) $ 21 $ 8 Debt and finance leases (72) (1,783) 77 53 (1) As of December 31, 2020, these amounts include the cumulative amount of fair value hedging adjustments remaining for which hedge accounting has been discontinued of approximately $76 million. Offsetting Assets and Liabilities We have master netting arrangements with our counterparties giving us the right to offset hedge assets and liabilities. However, we have elected not to offset the fair value positions recorded on our balance sheets. The following table shows the net fair value of our counterparty positions had we elected to offset. Derivative contracts offsetting assets and liabilities (in millions) Prepaid Expenses and Other Other Noncurrent Assets Other Accrued Liabilities Other Noncurrent Liabilities Hedge Derivatives, Net December 31, 2020 Net derivative contracts $ 3 $ 20 $ (9) $ (13) $ 1 December 31, 2019 Net derivative contracts $ 24 $ 53 $ (5) $ (4) $ 68 Not Designated Hedge Gains (Losses) Gains (losses) related to our foreign currency exchange and fuel contracts are as follows: Not designated hedge gains/(losses) by category Location of Gain (Loss) Recognized in Income Gain (Loss) Recognized in Income Year Ended December 31, (in millions) 2020 2019 2018 Foreign currency exchange contracts Gain/(loss) on investments, net $ (31) $ 10 $ (4) Fuel hedge contracts Aircraft fuel and related taxes 85 (41) 52 Total $ 54 $ (31) $ 48 Credit Risk To manage credit risk associated with our fuel price, interest rate and foreign currency hedging programs, we evaluate counterparties based on several criteria including their credit ratings and limit our exposure to any one counterparty. Our hedge contracts often contain margin funding requirements. The margin funding requirements may cause us to post margin to counterparties or may cause counterparties to post margin to us as market prices in the underlying hedged items change. Due to the fair value position of our hedge contracts, we held or posted no margin as of December 31, 2020 and posted margin of $34 million as of December 31, 2019. Accounts receivable primarily consist of amounts due from credit card companies from the sale of passenger tickets, ancillary businesses and refinery sales and other companies for the purchase of miles under the loyalty program. The credit risk associated with these receivables is minimal. See Note 5, "Investments," for further information on our receivables from our investees and other airlines. Self-Insurance Risk We self-insure a portion of our losses from claims related to workers' compensation, environmental issues, property damage, medical insurance for employees, healthcare for retirees, disability and general liability. Losses are accrued based on an estimate of the aggregate liability for claims incurred, using independent actuarial reviews based on standard industry practices and our historical experience.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	GOODWILL AND INTANGIBLE ASSETS Goodwill and Indefinite-Lived Intangible Assets Our goodwill and identifiable intangible assets relate to the airline segment. We apply a fair value-based impairment test to the carrying value of goodwill and indefinite-lived intangible assets on an annual basis (as of October 1) and, if certain events or circumstances indicate that an impairment loss may have been incurred, on an interim basis. We assess the value of our goodwill and indefinite-lived assets under either a qualitative or quantitative approach. Under a qualitative approach, we consider various market factors, including certain of the key assumptions listed below. We analyze these factors to determine if events and circumstances have affected the fair value of goodwill and indefinite-lived intangible assets. If we determine that it is more likely than not that the asset may be impaired, we use the quantitative approach to assess the asset's fair value and the amount of the impairment. Under a quantitative approach, we calculate the fair value of the asset incorporating the key assumptions listed below into our calculation. We value goodwill and indefinite-lived intangible assets primarily using market and income approach valuation techniques. These measurements include the following key assumptions (1) forecasted revenues, expenses and cash flows, including the duration and extent of impact to our business and our alliance partners from the COVID-19 pandemic, (2) current discount rates, (3) observable market transactions and (4) anticipated changes to the regulatory environment (e.g., diminished slot access, additional Open Skies agreements or changes to antitrust approvals). These assumptions are consistent with those that hypothetical market participants would use. Because we are required to make estimates and assumptions when evaluating goodwill and indefinite-lived intangible assets for impairment, actual transaction amounts may differ materially from these estimates. We recognize an impairment charge if the asset's carrying value exceeds its estimated fair value. Changes in certain events and circumstances could result in impairment or a change from indefinite-lived to definite-lived. Factors which could cause impairment include, but are not limited to (1) negative trends in our market capitalization, (2) reduced profitability resulting from lower passenger mile yields or higher input costs (primarily related to fuel and employees), (3) lower passenger demand as a result of weakened U.S. and global economies, global pandemics or other factors, (4) interruption to our operations due to a prolonged employee strike, terrorist attack or other reasons, (5) changes to the regulatory environment (e.g., diminished slot access, additional Open Skies agreements or changes to antitrust approvals), (6) competitive changes by other airlines and (7) strategic changes to our operations leading to diminished utilization of the intangible assets. Identifiable Intangible Assets. Indefinite-lived assets are not amortized and consist of routes, slots, the Delta tradename and assets related to alliances and collaborative arrangements. Definite-lived intangible assets consist primarily of marketing and maintenance service agreements and are amortized on a straight-line basis or under the undiscounted cash flows method over the estimated economic life of the respective agreements. Costs incurred to renew or extend the term of an intangible asset are expensed as incurred. As a result of the significant impact the COVID-19 pandemic has had on our market capitalization, profitability and overall travel demand, we performed a quantitative valuation of our goodwill and indefinite-lived intangible assets during 2020. Our December 2020 quarter quantitative impairment tests of goodwill and intangibles concluded that there was no indication of impairment as the fair value exceeded our carrying value: Goodwill and indefinite-lived intangible assets by category Carrying Value at Excess Fair Value at 2020 Testing Date (in millions) December 31, 2020 December 31, 2019 Goodwill (1) $ 9,753 $ 9,781 >100% International routes and slots 2,583 2,583 10% to 30% Airline alliances (2) 1,863 1,005 20% to >100% Delta tradename 850 850 >100% Domestic slots 622 622 60% to >100% Total $ 15,671 $ 14,841 (1) The reduction in goodwill relates to the combination of Delta Private Jets with Wheels Up in the March 2020 quart er. See Note 5, "Investments," for more information on this transaction. (2) As part of our strategic alliance with and investment in LATAM, we have recorded an alliance-related indefinite-lived intangible asset of $1.2 billion, which was not reflected in the December 31, 2019 balance. International Routes and Slots. Our international routes and slots primarily relate to Pacific route authorities and slots at capacity-constrained airports in Asia, and slots at London-Heathrow airport. Airline Alliances. Our airline alliances intangible assets primarily relate to our commercial agreements with LATAM and our SkyTeam partners. Domestic Slots. Our domestic slots primarily relate to our slots at New York-LaGuardia and Washington-Reagan National airports. Based on our impairment assessment as of our annual testing date of October 1, we determined that our goodwill and indefinite-lived intangible assets were not impaired. However, there are a number of uncertainties including how long conditions related to the pandemic will persist, when effective vaccines will be broadly available, when vaccination will be widespread globally, when travel advisories and restrictions will be lifted, what additional measures may be introduced by governments or private parties or what effect any such additional measures may have on air travel and our business. Any measure that requires or encourages potential travelers to stay in their homes, engage in social distancing or avoid larger gatherings of people is highly likely to be harmful to the air travel industry in general, and consequently our business, as these measures could delay the widespread return of demand for air travel. Definite-Lived Intangible Assets Definite-lived intangible assets by category December 31, 2020 December 31, 2019 (in millions) Gross Gross Marketing agreements $ 730 $ (696) $ 730 $ (692) Contracts 193 (134) 193 (128) Other 53 (53) 53 (53) Total $ 976 $ (883) $ 976 $ (873) Amortization expense was $10 million, $11 million and $17 million for the years ended December 31, 2020, 2019 and 2018, respectively. Based on our definite-lived intangible assets at December 31, 2020, we estimate that we will incur approximately $9 million of amortization expense annually from 2021 through 2025.

Debt

Debt	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Debt	DEBT The following table summarizes our debt as of the dates indicated below: Summary of outstanding debt by category Maturity Interest Rate(s) Per Annum at December 31, (in millions) Dates December 31, 2020 2020 2019 Unsecured notes 2021 to 2029 2.90% to 7.38% $ 5,350 $ 5,550 Unsecured CARES Act Payroll Support Program Loan (1) 2030 1.00% 1,648 — Financing arrangements secured by SkyMiles assets: SkyMiles Notes (2) 2023 to 2028 4.50% and 4.75% 6,000 — SkyMiles Term Loan (2)(3) 2023 to 2027 4.75% 3,000 — Financing arrangements secured by slots, gates and/or routes: 2020 Senior Secured Notes 2025 7.00% 3,500 — 2020 Term Loan (2)(3) 2021 to 2023 5.75% 1,493 — 2018 Revolving Credit Facility (3) 2021 to 2023 Undrawn — — Financing arrangements secured by aircraft: Certificates (2) 2021 to 2028 2.00% to 8.02% 2,633 1,669 Notes (2)(3) 2021 to 2032 0.81% to 5.75% 1,284 1,193 NYTDC Special Facilities Revenue Bonds, Series 2020 (2) 2026 to 2045 4.00% to 5.00% 1,511 — NYTDC Special Facilities Revenue Bonds, Series 2018 (2) 2022 to 2036 4.00% to 5.00% 1,383 1,383 Other financings (2)(3) 2021 to 2030 2.51% to 8.75% 412 196 Other revolving credit facilities (3) 2021 to 2022 Undrawn — — Total secured and unsecured debt 28,214 9,991 Unamortized (discount)/premium and debt issuance cost, net and other (240) 115 Total debt 27,974 10,106 Less: current maturities (1,443) (2,054) Total long-term debt $ 26,531 $ 8,052 (1) See Note 2, "Impact of the COVID-19 Pandemic," for further discussion of the terms, including the applicable interest rate. (2) Due in installments. (3) Certain aircraft and other financings are comprised of variable rate debt. All variable rates are equal to LIBOR (generally subject to a floor) or another index rate, in each case plus a specified margin. 2020 Unsecured Notes In the June 2020 quarter, we issued $1.3 billion in aggregate principal amount of 7.375% unsecured notes due 2026. The unsecured notes are equal in right of payment with our other unsubordinated indebtedness and senior in right of payment to future subordinated debt. The unsecured notes also contain event of default provisions consistent with those in our other recent unsecured debt offerings. Unsecured CARES Act Payroll Support Program Loan During 2020, we entered into a promissory note for the $1.6 billion CARES Act payroll support program loan and issued warrants to acquire more than 6.7 million shares of Delta common stock under the program in connection with the promissory note. We have recorded the value of the promissory note and warrants on a relative fair value basis as $1.5 billion of noncurrent debt, net of discount, and $114 million in additional paid in capital, respectively. See Note 2, "Impact of the COVID-19 Pandemic," for further discussion of the terms of the payroll support program loan. In January 2021, we issued a promissory note for approximately $400 million with respect to the term loan portion of the initial funds received from the payroll support program extension and issued warrants to acquire approximately 1 million shares of Delta common stock under the program as discussed in Note 2, "Impact of the COVID-19 Pandemic." The balance of the promissory note is expected to increase to approximately $830 million and the remaining warrants issued during the March 2021 quarter when we receive the remaining $1.5 billion in expected funding under the payroll support program extension. 2020 SkyMiles Financing In the September 2020 quarter, Delta and SkyMiles IP Ltd. ("SMIP"), an exempted company incorporated with limited liability under the laws of the Cayman Islands and an indirect wholly owned subsidiary of Delta, issued $2.5 billion in principal amount of 4.500% senior secured notes due 2025 and $3.5 billion in principal amount of 4.750% senior secured notes due 2028 (collectively, the “SkyMiles Notes”). Concurrently with the issuance of the SkyMiles Notes, Delta and SMIP entered into a term loan credit agreement and borrowed $3.0 billion (the “SkyMiles Term Loan” and together with the SkyMiles Notes, the “SkyMiles Debt”). The SkyMiles Term Loan matures in October 2027 and bears interest at a variable rate equal to LIBOR (but not less than 1.0% per annum), plus a margin of 3.75% per year. The SkyMiles Debt is guaranteed by three other Delta subsidiaries that are also exempted companies incorporated with limited liability under the laws of the Cayman Islands, including SkyMiles IP Finance Ltd. ("SMIF"). The SkyMiles Debt is secured by a first-priority security interest in certain of our co-branding, partnering or similar agreements relating to the SkyMiles program (including all payments thereunder), rights under certain intercompany agreements relating to the SkyMiles program, certain rights under our SkyMiles program, certain deposit accounts that receive revenue under our SkyMiles agreements, the equity of SMIP and substantially all other assets of SMIP and SMIF. The assets and credit of SMIP and the Cayman entity guarantors are not available to satisfy obligations, including indebtedness, of Delta or our subsidiaries other than with respect to the SkyMiles Debt and any permissible priority lien or junior lien debt subsequently incurred. 2020 Senior Secured Notes and Term Loan In the June 2020 quarter, we issued $3.5 billion of senior secured notes and entered into a $1.5 billion term loan secured by certain slots, gates and routes. The senior secured notes bear interest at an annual rate of 7.00% and mature in May 2025. The term loan bears interest at a variable rate equal to LIBOR plus a specified margin and is subject to principal payments of 1% per year, payable quarterly beginning in September 2020, with the balance due in April 2023. 2018 Revolving Credit Facility In the June 2020 quarter, we amended the 2018 revolving credit facility agreement to be secured by our Pacific route authorities and certain related assets. Additionally, the revolving credit facility was amended to extend the maturities of $1.3 billion of the revolver previously due in April 2021 to April 2022 and to include a minimum liquidity covenant, as discussed further below. In October 2020, we repaid the borrowings under the revolving credit facility. 2020 Secured Term Loan Facility In the March 2020 quarter, we entered into a $2.7 billion 364-day secured term loan facility, and we increased the borrowings thereunder to $3.0 billion in April 2020. Borrowings under this facility were secured by certain aircraft. In October 2020, we repaid all borrowings under, and terminated, this facility. 2020-1 EETC We completed a $1.0 billion offering of Class AA and A Pass Through Certificates, Series 2020-1 ("2020-1 EETC") utilizing a pass through trust during the March 2020 quarter. The proceeds of this issuance were used to repay unsecured notes that matured in the March 2020 quarter. In the June 2020 quarter, we issued an additional $135 million of Class B certificates. The details of the 2020-1 EETC, which is secured by 33 aircraft, are shown in the table below: 2020-1 EETC issuance by class (in millions) Total Principal Fixed Interest Rate Issuance Date Final Maturity Date 2020-1 Class AA Certificates $ 796 2.00 % March 2020 June 2028 2020-1 Class A Certificates 204 2.50 % March 2020 June 2028 2020-1 Class B Certificates 135 8.00 % April 2020 June 2027 Total $ 1,135 2019-1 EETC In the June 2020 quarter, we issued an additional $108 million of certificates under the 2019-1 EETC offering initially completed in March 2019. The additional certificates were issued as 2019-1 Class B Certificates with a fixed interest rate of 8.00% and mature in April 2023. New York Transportation Development Corporation ("NYTDC") Special Facilities Revenue Bonds, Series 2020 In the September 2020 quarter, the NYTDC issued Special Facilities Revenue Bonds, Series 2020 (the "Series 2020 Bonds") in the aggregate principal amount of $1.5 billion. We entered into loan agreements with the NYTDC to use the proceeds from the Series 2020 Bonds to finance a portion of the costs of the construction project that is currently in process at LaGuardia Airport, consisting of the demolition of existing Terminals C and D, the design and construction of new terminal facilities, the payment of capitalized interest on the Series 2020 Bonds and on a portion of the Special Facilities Revenue Bonds, Series 2018, and the payment of costs related to issuance of the Series 2020 Bonds. The proceeds from the Series 2020 Bonds are recorded in cash restricted for airport construction on our balance sheet, along with the remaining proceeds of the Series 2018 Bonds. See Note 10, "Airport Redevelopment," for further information on our LaGuardia Airport project. We are required to pay debt service on the Series 2020 Bonds through payments under loan agreements with NYTDC, and we have guaranteed the Series 2020 Bonds. Availability Under Revolving Facilities As of December 31, 2020, we had approximately $2.6 billion undrawn and available under our revolving credit facilities. In addition, we had outstanding letters of credit as of December 31, 2020, including approximately $300 million that reduced the availability under our revolvers and approximately $300 million that did not affect the availability under our revolvers. Fair Value of Debt Market risk associated with our fixed- and variable-rate debt relates to the potential reduction in fair value and negative impact to future earnings, respectively, from an increase in interest rates. The fair value of debt, shown below, is principally based on reported market values, recently completed market transactions and estimates based on interest rates, maturities, credit risk and underlying collateral. Debt is primarily classified as Level 2 within the fair value hierarchy. Fair value of outstanding debt (in millions) December 31, December 31, Net carrying amount $ 27,974 $ 10,106 Fair value $ 29,800 $ 10,400 Covenants Our debt agreements contain various affirmative, negative and financial covenants. For example, our credit facilities and our SkyMiles financing agreements, contain, among other things, a minimum liquidity covenant. The minimum liquidity covenant requires us to maintain at least $2.0 billion of liquidity (defined as cash, cash equivalents, short-term investments and aggregate principal amount committed and available to be drawn under our revolving credit facilities). Certain of our debt agreements also include collateral coverage ratios and limit our ability to (1) incur liens under certain circumstances, (2) dispose of collateral, (3) engage in mergers and consolidations or transfer all or substantially all of our assets and (4) pay dividends or repurchase our common stock through September 2021. Our SkyMiles financing agreements include a debt service coverage ratio and also restrict our ability to, among other things, (1) modify the terms of the SkyMiles program, or otherwise change the policies and procedures of the SkyMiles program, in a manner that would reasonably be expected to materially impair repayment of the SkyMiles Debt, (2) sell pre-paid miles in excess of $550 million in the aggregate and (3) terminate or materially modify the intercompany arrangements governing the relationship between Delta and SMIP with respect to the SkyMiles program. Each of these restrictions, however, is subject to certain exceptions and qualifications that are set forth in these debt agreements. We were in compliance with the covenants in our debt agreements at December 31, 2020. Future Maturities The following table summarizes scheduled maturities of our debt for the years succeeding December 31, 2020: Future debt maturities Total Debt Amortization of 2021 $ 1,480 $ (62) 2022 1,882 (63) 2023 4,016 (54) 2024 3,126 (46) 2025 5,157 (23) Thereafter 12,553 8 Total $ 28,214 $ (240) $ 27,974

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	LEASES We lease property and equipment under finance and operating leases. For leases with terms greater than 12 months, we record the related asset and obligation at the present value of lease payments over the term. Many of our leases include rental escalation clauses, renewal options and/or termination options that are factored into our determination of lease payments when appropriate. We do not separate lease and nonlease components of contracts, except for regional aircraft and information technology ("IT") assets as discussed below. When available, we use the rate implicit in the lease to discount lease payments to present value; however, we have an insignificant number of leases representing an immaterial portion of our lease liability that provide readily determinable implicit rates. When the rate implicit in the lease is not available, we use our incremental borrowing rate, which is based on the estimated interest rate for collateralized borrowing over a similar term of the lease at commencement date. Some of our aircraft lease agreements include provisions for residual value guarantees. These provisions primarily relate to our regional aircraft and the amounts are not significant. We do not have other forms of variable interests with the lessors of our leased assets, other than at New York-JFK, in which we are not the primary beneficiary as discussed in Note 10, "Airport Redevelopment," and with respect to one lessor, in which we have a variable interest in certain immaterial aircraft leases, that we have consolidated. Aircraft As of December 31, 2020, including aircraft operated by our regional carriers, we leased 353 aircraft, of which 145 were under finance leases and 208 were operating leases. Our aircraft leases had remaining lease terms of one month to 15 years. In addition, we have regional aircraft leases that are embedded within our capacity purchase agreements and included in the operating right-of-use ("ROU") asset and lease liability. We allocated the consideration in each capacity purchase agreement to the lease and nonlease components based on their relative standalone value. Lease components of these agreements consist of 125 aircraft as of December 31, 2020 and nonlease components primarily consist of flight operations, in-flight and maintenance services. We determined our best estimate of the standalone value of the individual components by considering observable information including rates paid by our wholly owned subsidiary, Endeavor Air, Inc., and rates published by independent valuation firms. See Note 12, "Commitments and Contingencies," for additional information about our capacity purchase agreements. Airport Facilities Our facility leases are primarily for space at approximately 300 airports around the world that we serve. These leases reflect our use of airport terminals, office space, cargo warehouses and maintenance facilities. We generally lease space from government agencies that control the use of the airport, and as a result, these leases are classified as operating leases. The remaining lease terms vary from one month to 30 years. At the majority of the U.S. airports, the lease rates depend on airport operating costs or use of the facilities and are reset at least annually. Because of the variable nature of the rates, these leases are not recorded on our balance sheet as a ROU asset and lease liability. Some airport facilities have fixed payment schedules, the most significant of which are New York-LaGuardia and New York-JFK. For those airport leases, we have recorded a ROU asset and lease liability representing the fixed component of the lease payment. See Note 10, "Airport Redevelopment," for more information on our significant airport redevelopment projects. Other Ground Property and Equipment We lease certain IT assets (including servers, mainframes, etc.), ground support equipment (including tugs, tractors, fuel trucks and de-icers), and various other equipment. The remaining lease terms range from one month to nine years. Certain leased assets are embedded within various ground and IT service agreements. For ground service contracts, we have elected to include both the lease and nonlease components in the lease asset and lease liability balances on our balance sheet. For IT service contracts, we have elected to separate the lease and nonlease components and only the lease components are included in the lease asset and lease liability balances on our balance sheet. The amounts of these lease and nonlease components are not significant. Sale-Leaseback Transactions In 2020, we entered into $2.8 billion of sale-leaseback transactions for 85 aircraft including 25 A321-200s, 25 A220-100s, 23 CRJ-900s, 10 737-900ERs and two A330-900s. Of these transactions, 74 did not qualify as a sale as they are finance leases or have an option to repurchase at a stated price. The assets associated with these transactions remain on our balance sheet within property and equipment, net and we recorded the related liabilities under the lease. These liabilities are classified within other accrued or other noncurrent liabilities on our balance sheet. The cash proceeds are treated as financing inflows on the cash flows statement. The other 11 transactions qualified as sales, generating an immaterial loss, and the associated assets were removed from our balance sheet within property and equipment, net and recorded within ROU assets. The liabilities are recorded within current maturities of operating leases and noncurrent operating leases on our balance sheet. The cash proceeds are treated as investing cash inflows on the cash flows statement. Lease Position The table below presents the lease-related assets and liabilities recorded on the balance sheet. Lease asset and liability balance sheet position by category December 31, (in millions) Classification on the Balance Sheet 2020 2019 Assets Operating lease assets Operating lease right-of-use assets $ 5,733 $ 5,627 Finance lease assets Property and equipment, net 1,002 1,062 Total lease assets $ 6,735 $ 6,689 Liabilities Current Operating Current maturities of operating leases $ 678 $ 801 Finance Current maturities of debt and finance leases 289 233 Noncurrent Operating Noncurrent operating leases 5,713 5,294 Finance Debt and finance leases 894 821 Total lease liabilities $ 7,574 $ 7,149 Weighted-average remaining lease term Operating leases 12 years 12 years Finance leases 5 years 5 years Weighted-average discount rate Operating leases 4.88 % 3.73 % Finance leases 3.61 % 3.46 % Lease Costs The table below presents certain information related to the lease costs for finance and operating leases. Lease cost by category Year Ended December 31, (in millions) 2020 2019 2018 Finance lease cost Amortization of leased assets $ 131 $ 110 $ 100 Interest of lease liabilities 32 29 22 Operating lease cost (1) 1,019 1,013 994 Short-term lease cost (1) 264 500 458 Variable lease cost (1) 1,406 1,456 1,427 Total lease cost $ 2,852 $ 3,108 $ 3,001 (1) Expenses are classified within aircraft rent, landing fees and other rents and regional carriers expense, excluding fuel on the income statement. For the year ended December 31, 2020, $187 million and $50 million of the operating and variable lease costs, respectively, for the year ended December 31, 2019, $174 million and $64 million of the operating and variable lease costs, respectively, and for the year ended December 31, 2018, $150 million, $18 million and $48 million of the operating, short-term and variable lease costs, respectively, are attributable to our regional carriers. Other Information The table below presents supplemental cash flow information related to leases. Supplemental lease-related cash flow information Year Ended December 31, (in millions) 2020 2019 2018 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows for operating leases $ 1,053 $ 1,166 $ 1,271 Operating cash flows for finance leases 32 27 22 Financing cash flows for finance leases 255 192 108 Undiscounted Cash Flows The table below reconciles the undiscounted cash flows for each of the first five years and total of the remaining years to the finance lease liabilities and operating lease liabilities recorded on the balance sheet. Future lease cash flows and reconciliation to the balance sheet (in millions) Operating Leases Finance Leases 2021 $ 949 $ 328 2022 848 238 2023 837 191 2024 770 266 2025 746 128 Thereafter 4,450 149 Total minimum lease payments 8,600 1,300 Less: amount of lease payments representing interest (2,209) (117) Present value of future minimum lease payments 6,391 1,183 Less: current obligations under leases (678) (289) Long-term lease obligations $ 5,713 $ 894
Leases	LEASES We lease property and equipment under finance and operating leases. For leases with terms greater than 12 months, we record the related asset and obligation at the present value of lease payments over the term. Many of our leases include rental escalation clauses, renewal options and/or termination options that are factored into our determination of lease payments when appropriate. We do not separate lease and nonlease components of contracts, except for regional aircraft and information technology ("IT") assets as discussed below. When available, we use the rate implicit in the lease to discount lease payments to present value; however, we have an insignificant number of leases representing an immaterial portion of our lease liability that provide readily determinable implicit rates. When the rate implicit in the lease is not available, we use our incremental borrowing rate, which is based on the estimated interest rate for collateralized borrowing over a similar term of the lease at commencement date. Some of our aircraft lease agreements include provisions for residual value guarantees. These provisions primarily relate to our regional aircraft and the amounts are not significant. We do not have other forms of variable interests with the lessors of our leased assets, other than at New York-JFK, in which we are not the primary beneficiary as discussed in Note 10, "Airport Redevelopment," and with respect to one lessor, in which we have a variable interest in certain immaterial aircraft leases, that we have consolidated. Aircraft As of December 31, 2020, including aircraft operated by our regional carriers, we leased 353 aircraft, of which 145 were under finance leases and 208 were operating leases. Our aircraft leases had remaining lease terms of one month to 15 years. In addition, we have regional aircraft leases that are embedded within our capacity purchase agreements and included in the operating right-of-use ("ROU") asset and lease liability. We allocated the consideration in each capacity purchase agreement to the lease and nonlease components based on their relative standalone value. Lease components of these agreements consist of 125 aircraft as of December 31, 2020 and nonlease components primarily consist of flight operations, in-flight and maintenance services. We determined our best estimate of the standalone value of the individual components by considering observable information including rates paid by our wholly owned subsidiary, Endeavor Air, Inc., and rates published by independent valuation firms. See Note 12, "Commitments and Contingencies," for additional information about our capacity purchase agreements. Airport Facilities Our facility leases are primarily for space at approximately 300 airports around the world that we serve. These leases reflect our use of airport terminals, office space, cargo warehouses and maintenance facilities. We generally lease space from government agencies that control the use of the airport, and as a result, these leases are classified as operating leases. The remaining lease terms vary from one month to 30 years. At the majority of the U.S. airports, the lease rates depend on airport operating costs or use of the facilities and are reset at least annually. Because of the variable nature of the rates, these leases are not recorded on our balance sheet as a ROU asset and lease liability. Some airport facilities have fixed payment schedules, the most significant of which are New York-LaGuardia and New York-JFK. For those airport leases, we have recorded a ROU asset and lease liability representing the fixed component of the lease payment. See Note 10, "Airport Redevelopment," for more information on our significant airport redevelopment projects. Other Ground Property and Equipment We lease certain IT assets (including servers, mainframes, etc.), ground support equipment (including tugs, tractors, fuel trucks and de-icers), and various other equipment. The remaining lease terms range from one month to nine years. Certain leased assets are embedded within various ground and IT service agreements. For ground service contracts, we have elected to include both the lease and nonlease components in the lease asset and lease liability balances on our balance sheet. For IT service contracts, we have elected to separate the lease and nonlease components and only the lease components are included in the lease asset and lease liability balances on our balance sheet. The amounts of these lease and nonlease components are not significant. Sale-Leaseback Transactions In 2020, we entered into $2.8 billion of sale-leaseback transactions for 85 aircraft including 25 A321-200s, 25 A220-100s, 23 CRJ-900s, 10 737-900ERs and two A330-900s. Of these transactions, 74 did not qualify as a sale as they are finance leases or have an option to repurchase at a stated price. The assets associated with these transactions remain on our balance sheet within property and equipment, net and we recorded the related liabilities under the lease. These liabilities are classified within other accrued or other noncurrent liabilities on our balance sheet. The cash proceeds are treated as financing inflows on the cash flows statement. The other 11 transactions qualified as sales, generating an immaterial loss, and the associated assets were removed from our balance sheet within property and equipment, net and recorded within ROU assets. The liabilities are recorded within current maturities of operating leases and noncurrent operating leases on our balance sheet. The cash proceeds are treated as investing cash inflows on the cash flows statement. Lease Position The table below presents the lease-related assets and liabilities recorded on the balance sheet. Lease asset and liability balance sheet position by category December 31, (in millions) Classification on the Balance Sheet 2020 2019 Assets Operating lease assets Operating lease right-of-use assets $ 5,733 $ 5,627 Finance lease assets Property and equipment, net 1,002 1,062 Total lease assets $ 6,735 $ 6,689 Liabilities Current Operating Current maturities of operating leases $ 678 $ 801 Finance Current maturities of debt and finance leases 289 233 Noncurrent Operating Noncurrent operating leases 5,713 5,294 Finance Debt and finance leases 894 821 Total lease liabilities $ 7,574 $ 7,149 Weighted-average remaining lease term Operating leases 12 years 12 years Finance leases 5 years 5 years Weighted-average discount rate Operating leases 4.88 % 3.73 % Finance leases 3.61 % 3.46 % Lease Costs The table below presents certain information related to the lease costs for finance and operating leases. Lease cost by category Year Ended December 31, (in millions) 2020 2019 2018 Finance lease cost Amortization of leased assets $ 131 $ 110 $ 100 Interest of lease liabilities 32 29 22 Operating lease cost (1) 1,019 1,013 994 Short-term lease cost (1) 264 500 458 Variable lease cost (1) 1,406 1,456 1,427 Total lease cost $ 2,852 $ 3,108 $ 3,001 (1) Expenses are classified within aircraft rent, landing fees and other rents and regional carriers expense, excluding fuel on the income statement. For the year ended December 31, 2020, $187 million and $50 million of the operating and variable lease costs, respectively, for the year ended December 31, 2019, $174 million and $64 million of the operating and variable lease costs, respectively, and for the year ended December 31, 2018, $150 million, $18 million and $48 million of the operating, short-term and variable lease costs, respectively, are attributable to our regional carriers. Other Information The table below presents supplemental cash flow information related to leases. Supplemental lease-related cash flow information Year Ended December 31, (in millions) 2020 2019 2018 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows for operating leases $ 1,053 $ 1,166 $ 1,271 Operating cash flows for finance leases 32 27 22 Financing cash flows for finance leases 255 192 108 Undiscounted Cash Flows The table below reconciles the undiscounted cash flows for each of the first five years and total of the remaining years to the finance lease liabilities and operating lease liabilities recorded on the balance sheet. Future lease cash flows and reconciliation to the balance sheet (in millions) Operating Leases Finance Leases 2021 $ 949 $ 328 2022 848 238 2023 837 191 2024 770 266 2025 746 128 Thereafter 4,450 149 Total minimum lease payments 8,600 1,300 Less: amount of lease payments representing interest (2,209) (117) Present value of future minimum lease payments 6,391 1,183 Less: current obligations under leases (678) (289) Long-term lease obligations $ 5,713 $ 894

Airport Redevelopment

Airport Redevelopment	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Airport Redevelopment	AIRPORT REDEVELOPMENT New York-JFK Airport In 2015, we completed two phases of redevelopment at New York-JFK's Terminal 4 to facilitate convenient connections for our passengers and improve coordination with our SkyTeam alliance partners. Terminal 4 is operated by JFK International Air Terminal LLC ("IAT"), a private party, under its lease with the Port Authority of New York and New Jersey ("Port Authority"). In December 2010, we entered into a 33-year agreement with IAT ("Sublease") to sublease space in Terminal 4. Also, in 2010, the Port Authority issued approximately $800 million principal amount of special project bonds (the "Series 8 Bonds") to fund the majority of the project. In December 2020, the NYTDC issued approximately $611 million principal amount of special project bonds to refinance the outstanding balance of the Series 8 Bonds. We have recognized a ROU asset and lease liability representing the fixed component of the lease payments for this facility. We have an equity method investment in JFK IAT Member LLC, which owns IAT, our sublessor at Terminal 4. The Sublease requires us to pay certain fixed management fees. We determined the investment is a variable interest entity and assessed whether we have a controlling financial interest in IAT. Our rights under the Sublease, with respect to management of Terminal 4, are consistent with rights granted to an anchor tenant under a standard airport lease. Accordingly, we do not consolidate this entity in our Consolidated Financial Statements. We continue to plan for further expansion of Terminal 4, however changes in the JFK market due to the COVID-19 pandemic have caused us to reevaluate our original plan to expand the terminal by 16 gates. We are working with the Port Authority and IAT to evaluate our options and determine the optimal size, scope and phasing of the expansion. Los Angeles International Airport ("LAX") We executed a modified lease agreement during 2016 with the City of Los Angeles (the "City"), which owns and operates LAX, and announced plans to modernize, upgrade and provide post-security connection to Terminals 2 and 3. Construction is underway, which includes a new centralized ticketing and arrival hall, a new security checkpoint, core infrastructure to support the City's planned airport people mover, ramp improvements and a post-security connector to the north side of the Tom Bradley International Terminal. Given reduced passenger volumes resulting from the COVID-19 pandemic, we have accelerated the construction schedule for this project. Additionally, in 2020, we enhanced the project’s scope to include a more customer-friendly design of Terminal 3, a Delta One lounge and expanded Delta Sky Club, and baggage system upgrades designed to increase the terminals’ operational efficiency going forward. Construction is expected to be completed by 2023. The project is expected to cost approximately $2.3 billion. A substantial majority of the project costs are being funded through the Regional Airports Improvement Corporation ("RAIC"), a California public benefit corporation, using an $800 million revolving credit facility provided by a group of lenders. The credit facility was executed during 2017 and amended in 2020, and we have guaranteed the obligations of the RAIC under the credit facility. Loans made under the credit facility are being repaid with the proceeds from the City’s purchase of completed project assets. Under the lease agreement and subsequent project component approvals by the City's Board of Airport Commissioners, the City has appropriated to date approximately $1.8 billion to purchase completed project assets, representing the maximum allowable reimbursement by the City. Costs incurred in excess of the $1.8 billion maximum will not be reimbursed by the City. We currently expect our net project costs to be approximately $500 million, of which approximately $200 million has been reflected as investing activities in our cash flows statement since the project started in 2017. In 2020, $315 million was spent on this project, with $293 million paid by the credit facility and $22 million paid directly by Delta. Based on our assessment of the project, we concluded that we do not control the underlying assets being constructed, and therefore, we do not have the project asset or related obligation recorded on our balance sheet. New York-LaGuardia Airport As part of the terminal redevelopment project at LaGuardia Airport, we are partnering with the Port Authority to replace Terminals C and D with a new state-of-the-art terminal facility consisting of 37 gates across four concourses connected to a central headhouse. The terminal will feature a new, larger Delta Sky Club, wider concourses, more gate seating and 75 percent more concessions space than the existing terminals. The facility will also offer direct access between the parking garage and terminal and improved roadways and drop-off/pick-up areas. The design of the new terminal will integrate sustainable technologies and improvements in energy efficiency. Construction will be phased to limit passenger inconvenience and is expected to be completed by 2026. In connection with the redevelopment, during 2017, we entered into an amended and restated terminal lease with the Port Authority with a term through 2050. Pursuant to the lease agreement, as amended to date, we will (1) fund (through debt issuance and existing cash) and undertake the design, management and construction of the terminal and certain off-premises supporting facilities, (2) receive a Port Authority contribution of $481 million to facilitate construction of the terminal and other supporting infrastructure, (3) be responsible for all operations and maintenance during the term of the lease and (4) have preferential rights to all gates in the terminal subject to Port Authority requirements with respect to accommodation of designated carriers. We currently expect our net project cost to be approximately $3.5 billion and we bear the risks of project construction, including any potential cost over-runs. Using funding primarily provided by existing financing arrangements, we spent approximately $600 million during 2020, bringing the total amount spent on the project to date to approximately $1.5 billion. See Note 8, "Debt," for additional information on the debt related to this redevelopment project, NYTDC Special Facilities Revenue Bonds, Series 2018 and NYTDC Special Facilities Revenue Bonds, Series 2020. In 2019, we opened Concourse G, the first of the four new concourses housing seven of the 37 new gates. Not only did it deliver the first direct impact to the Delta passenger experience, it also represented the first major phasing milestone. The next major milestone will be the opening of the headhouse and Concourse E, which is scheduled for 2022. As we are funding the majority of the LaGuardia redevelopment project, we account for the related assets as leasehold improvements. We entered into loan agreements to fund a portion of the construction, which are recorded on our balance sheet as debt with the proceeds reflected as restricted cash.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS We sponsor defined benefit and defined contribution pension plans, healthcare plans and disability and survivorship plans for eligible employees and retirees and their eligible family members. Defined Benefit Pension Plans. We sponsor defined benefit pension plans for eligible employees and retirees. These plans are closed to new entrants and frozen for future benefit accruals. The Pension Protection Act of 2006 allows commercial airlines to elect alternative funding rules ("Alternative Funding Rules") for defined benefit plans that are frozen. We elected the Alternative Funding Rules under which the unfunded liability for a frozen defined benefit plan may be amortized over a fixed 17-year period and is calculated using an 8.85% discount rate until the 17-year period expires for all frozen defined benefit plans by the end of 2024. We have no minimum funding requirements in 2021, but we plan to voluntarily contribute at least $500 million to these plans during 2021. Defined Contribution Pension Plans. We sponsor several defined contribution plans. These plans generally cover different employee groups and employer contributions vary by plan. The costs associated with our defined contribution pension plans were approximately $805 million, $1.0 billion and $925 million for the years ended December 31, 2020, 2019 and 2018, respectively. Postretirement Healthcare Plans. We sponsor healthcare plans that provide benefits to eligible retirees and their dependents who are under age 65. We have generally eliminated company-paid post age 65 healthcare coverage, except for (1) subsidies available to a limited group of retirees and their dependents, (2) a group of retirees who retired prior to 1987 and (3) retiree medical accounts which provide a fixed dollar amount to eligible employees who retired in 2012 or in 2020. Benefits under these plans are funded from current assets and employee contributions. During the September 2020 quarter, we remeasured our postretirement healthcare obligation to account for the retiree medical accounts provided to eligible participants in our voluntary early retirement and separation programs ("voluntary programs"). As a result, we recorded a $1.3 billion special termination benefit charge and increased our postretirement healthcare obligation by $1.3 billion. Postemployment Plans. We provide certain other welfare benefits to eligible former or inactive employees after employment but before retirement, primarily as part of the disability and survivorship plans. Substantially all employees are eligible for benefits under these plans in the event of death and/or disability. Benefit Obligations, Fair Value of Plan Assets and Funded Status Pension Benefits Other Postretirement and Postemployment Benefits December 31, December 31, (in millions) 2020 2019 2020 2019 Benefit obligation at beginning of period $ 21,199 $ 19,809 $ 3,379 $ 3,225 Service cost — — 96 83 Interest cost 700 833 120 137 Actuarial loss 2,051 1,678 247 226 Benefits paid, including lump sums and annuities (1,233) (1,107) (356) (315) Participant contributions — — 20 23 Special termination benefits — — 1,260 — Settlements (91) (14) — — Benefit obligation at end of period (1) $ 22,626 $ 21,199 $ 4,766 $ 3,379 Fair value of plan assets at beginning of period $ 15,845 $ 13,459 $ 607 $ 637 Actual gain on plan assets 1,973 2,485 76 134 Employer contributions 47 1,022 189 159 Participant contributions — — 20 23 Benefits paid, including lump sums and annuities (1,233) (1,107) (396) (346) Settlements (91) (14) — — Fair value of plan assets at end of period $ 16,541 $ 15,845 $ 496 $ 607 Funded status at end of period $ (6,085) $ (5,354) $ (4,270) $ (2,772) (1) At the end of each year presented, our accumulated benefit obligations for our pension plans are equal to the benefit obligations shown above. During 2020 and 2019, net actuarial losses increased our benefit obligation primarily due to the decrease in discount rates . These gains and losses are recorded in AOCI and reflected in the table below. Balance Sheet Position Pension Benefits Other Postretirement and Postemployment Benefits December 31, December 31, (in millions) 2020 2019 2020 2019 Current liabilities $ (10) $ (19) $ (143) $ (125) Noncurrent liabilities (6,075) (5,335) (4,127) (2,647) Total liabilities $ (6,085) $ (5,354) $ (4,270) $ (2,772) Net actuarial loss $ (9,878) $ (8,765) $ (886) $ (715) Prior service credit — — 29 38 Total accumulated other comprehensive loss, pre-tax $ (9,878) $ (8,765) $ (857) $ (677) Net Periodic (Benefit) Cost Pension Benefits Other Postretirement and Postemployment Benefits Year Ended December 31, Year Ended December 31, (in millions) 2020 2019 2018 2020 2019 2018 Service cost $ — $ — $ — $ 96 $ 83 $ 85 Interest cost 700 833 781 120 137 126 Expected return on plan assets (1,373) (1,186) (1,318) (44) (47) (67) Amortization of prior service credit — — — (9) (9) (24) Recognized net actuarial loss 300 291 267 44 37 36 Settlements 38 5 4 — — — Special termination benefits — — — 1,260 — — Curtailment — — — — — (53) Net periodic (benefit) cost $ (335) $ (57) $ (266) $ 1,467 $ 201 $ 103 Service cost is recorded in salaries and related costs in the income statement. Special termination benefits are recorded in restructuring charges, while all other components are recorded within miscellaneous, net under non-operating expense. Assumptions We used the following actuarial assumptions to determine our benefit obligations and our net periodic benefit cost for the periods presented: December 31, Benefit Obligations (1) 2020 2019 Weighted average discount rate 2.62 % 3.40 % Year Ended December 31, Net Periodic (Benefit) Cost (1) 2020 2019 2018 Weighted average discount rate - pension benefit 3.40 % 4.33 % 3.69 % Weighted average discount rate - other postretirement benefit 3.47 % 4.32 % 3.69 % Weighted average discount rate - other postemployment benefit 3.34 % 4.32 % 3.65 % Weighted average expected long-term rate of return on plan assets 8.97 % 8.97 % 8.97 % Assumed healthcare cost trend rate for the next year (2) 6.25 % 6.50 % 6.75 % (1) Future employee compensation levels do not impact our frozen defined benefit pension plans or other postretirement plans and impact only a small portion of our other postemployment obligation. (2) Healthcare cost trend rate is assumed to decline gradually to 5.00% by 2026 and remain unchanged thereafter. Expected Long-Term Rate of Return. Our expected long-term rate of return on plan assets is based primarily on plan-specific investment studies using historical market return and volatility data. Modest excess return expectations versus some public market indices are incorporated into the return projections based on the actively managed structure of the investment programs and their records of achieving such returns historically. We also expect to receive a premium for investing in less liquid private markets. We review our rate of return on plan assets assumptions annually. Our annual investment performance for one particular year does not, by itself, significantly influence our evaluation. The investment strategy for our defined benefit pension plan assets is to earn a long-term return that meets or exceeds our annualized return target while taking an acceptable level of risk and maintaining sufficient liquidity to pay current benefits and other cash obligations of the plan. This is achieved by investing in a globally diversified mix of public and private equity, fixed income, real assets, hedge funds and other assets and instruments. Our weighted average expected long-term rate of return on assets for net periodic benefit cost for the year ended December 31, 2020 was 8.97%. Life Expectancy . Changes in life expectancy may significantly impact our benefit obligations and future net periodic benefit cost. We use the Society of Actuaries ("SOA") published mortality data and other publicly available information to develop our best estimate of life expectancy. The SOA publishes updated mortality tables for U.S. plans and updated improvement scales. Each year we consider updates by the SOA in setting our mortality assumptions for purposes of measuring pension and other postretirement and postemployment benefit obligations. Benefit Payments Benefit payments in the table below are based on the same assumptions used to measure the related benefit obligations. Actual benefit payments may vary significantly from these estimates. Benefits earned under our pension plans and certain postemployment benefit plans are expected to be paid from funded benefit plan trusts, while our other postretirement benefits are funded from current assets. The following table summarizes the benefit payments that are expected to be paid in the years ending December 31: Expected future benefit payments (in millions) Pension Benefits Other Postretirement and Postemployment Benefits 2021 $ 1,280 $ 340 2022 1,270 370 2023 1,270 410 2024 1,270 430 2025 1,270 430 2026-2030 6,210 2,110 Plan Assets We have adopted and implemented investment policies for our defined benefit pension plans that incorporate strategic asset allocation mixes intended to best meet the plans' long-term obligations, while maintaining an appropriate level of risk and liquidity. These asset portfolios employ a diversified mix of investments, which are reviewed periodically. Active management strategies are utilized where feasible in an effort to realize investment returns in excess of market indices. Derivatives in the plans are primarily used to manage risk and gain asset class exposure while still maintaining liquidity. As part of these strategies, the plans are required to hold cash collateral associated with certain derivatives. Our investment strategies target a mix of 30-50% growth-seeking assets, 25-35% income-generating assets and 30-40% risk-diversifying assets. Risk diversifying assets include hedged mandates implementing long-short, market neutral and relative value strategies that invest primarily in publicly-traded equity, fixed income, foreign currency and commodity securities and are used to improve the impact of active management on the plans. Benefit Plan Assets Measured at Fair Value on a Recurring Basis Benefit Plan Assets. Benefit plan assets relate to our defined benefit pension plans and certain of our postemployment benefit plans. These investments are presented net of the related benefit obligation in pension, postretirement and related benefits on the balance sheets. See Note 4, "Fair Value Measurements," for a description of the levels within the fair value hierarchy and associated valuation techniques used to measure fair value. The following table shows our benefit plan assets by asset class. Benefit plan assets measured at fair value on a recurring basis December 31, 2020 December 31, 2019 Valuation Technique (in millions) Level 1 Level 2 Total Level 1 Level 2 Total Equities and equity-related instruments $ 1,061 $ 59 $ 1,120 $ 840 $ 49 $ 889 (a) Delta common stock 507 — 507 737 — 737 (a) Cash equivalents 305 3,359 3,664 327 952 1,279 (a) Fixed income and fixed income-related instruments — 882 882 97 3,472 3,569 (a)(b) Benefit plan assets $ 1,873 $ 4,300 $ 6,173 $ 2,001 $ 4,473 $ 6,474 Investments measured at net asset value ("NAV") (1) 10,427 9,854 Total benefit plan assets $ 16,600 $ 16,328 (1) Investments that were measured at NAV per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. Equities and Equity-Related Instruments. These investments include common stock and equity-related instruments. Common stock is valued at the closing price reported on the active market on which the individual securities are traded. Equity-related instruments include investments in securities traded on exchanges, including listed futures and options, which are valued at the last reported sale prices on the last business day of the year or, if not available, the last reported bid prices. Over-the-counter securities are valued at the bid prices or the average of the bid and ask prices on the last business day of the year from published sources or, if not available, from other sources considered reliable, generally broker quotes. Delta Common Stock. The Delta common stock investment is managed by an independent fiduciary. Cash Equivalents. These investments primarily consist of high-quality, short-term obligations that are a part of institutional money market mutual funds that are valued using current market quotations or an appropriate substitute that reflects current market conditions. Fixed Income and Fixed Income-Related Instruments. These investments include corporate bonds, government bonds, collateralized mortgage obligations and other asset-backed securities, and are generally valued at the bid price or the average of the bid and ask price. Prices are based on pricing models, quoted prices of securities with similar characteristics or broker quotes. Fixed income-related instruments include investments in securities traded on exchanges, including listed futures and options, which are valued at the last reported sale prices on the last business day of the year, or if not available, the last reported bid prices. Over-the-counter securities are valued at the bid prices or the average of the bid and ask prices on the last business day of the year from published sources or, if not available, from other sources considered reliable, generally broker quotes. The following table summarizes investments measured at fair value based on NAV per share as a practical expedient: Benefit plan investment assets measured at NAV December 31, 2020 December 31, 2019 (in millions) Fair Value Redemption Frequency Redemption Notice Period Fair Value Redemption Frequency Redemption Notice Period Hedge funds and hedge fund-related strategies (4) $ 5,474 (3) 2-180 Days $ 5,588 (3) 2-180 Days Commingled funds, private equity and private equity-related instruments (4) 2,136 (3) 3-30 Days 1,834 (3) 2-30 Days Fixed income and fixed income-related instruments (4) 1,118 (3) 15-90 Days 958 (3) 15-90 Days Real assets (4) 671 (2) N/A 758 (2) N/A Other 1,028 (1) 2-90 Days 716 (1) 2-90 Days Total investments measured at NAV $ 10,427 $ 9,854 (1) Weekly, semi-monthly, monthly (2) Semi-annually and annually (3) Various. Includes funds with weekly, semi-monthly, monthly, quarterly and custom redemption frequencies as well as funds with a redemption window following the anniversary of the initial investment. (4) Unfunded commitments were $916 million for commingled funds, private equity and private equity-related instruments, $264 million for fixed income and fixed income-related instruments and $181 million for real assets at December 31, 2020. Hedge Funds and Hedge Fund-Related Strategies. These investments are primarily made through shares of limited partnerships or similar structures for which a liquid secondary market does not exist. Commingled Funds, Private Equity and Private Equity-Related Instruments. These investments include commingled funds invested in common stock, as well as private equity and private equity-related instruments. Commingled funds are valued based on quoted market prices of the underlying assets owned by the fund. Private equity and private equity-related strategies are typically valued quarterly by the fund managers using valuation models where one or more of the significant inputs into the model cannot be observed and which require the development of assumptions. Fixed Income and Fixed Income-Related Instruments. These investments include commingled funds invested in debt obligations. Commingled funds are valued based on quoted market prices of the underlying assets owned by the fund. Private fixed income strategies are typically valued monthly or quarterly by the fund managers or third-party valuation agents using valuation models where one or more of significant inputs into the model cannot be observed and which require the development of assumptions. Real Assets. These investments include real estate, energy, timberland, agriculture and infrastructure. The valuation of real assets requires significant judgment due to the absence of quoted market prices as well as the inherent lack of liquidity and the long-term nature of these assets. Real assets are typically valued quarterly by the fund managers using valuation models where one or more of the significant inputs into the model cannot be observed and which require the development of assumptions. Other. Primarily includes globally-diversified, risk-managed commingled funds consisting mainly of equity, fixed income and commodity exposures. On an annual basis we assess the potential for adjustments to the fair value of all investments. These investments valued using NAV as a practical expedient are typically valued on a monthly or quarterly basis by third-party administrators, valuation agents or fund managers with an annual audit performed by an independent third party, but certain of these investments have a lag in the availability of data. This primarily applies to private equity, private equity-related strategies and real assets. We solicit valuation updates from the investment fund managers and use their information and corroborating data from public markets to determine any needed fair value adjustments. Other We also sponsor defined benefit pension plans for eligible employees in certain foreign countries. These plans did not have a material impact on our Consolidated Financial Statements in any period presented. Voluntary Programs During the June 2020 quarter in response to the COVID-19 pandemic, we announced the voluntary programs, which primarily applied to eligible U.S. merit, ground and flight attendant and pilot employees. The employees electing to participate in the voluntary programs were eligible for separation payments, continued healthcare benefits and certain participants will receive retiree medical accounts. The election and revocation windows for these programs closed during the September 2020 quarter with approximately 18,000 employees electing to participate. We recorded $3.4 billion in restructuring charges in our income statement associated with these programs and other employee benefit charges during 2020, including $1.3 billion of special termination benefits (discussed above). The remainder of the restructuring charge primarily relates to separation payments and healthcare benefits. Approximately $720 million was disbursed in cash payments to participants in the voluntary programs during 2020. An additional approximately $250 million of cash payments were disbursed during 2020 related to unused vacation and other benefits, which were accrued prior to the voluntary programs charge. Accruals related to the voluntary programs are primarily recorded in pension, postretirement and related benefits, other noncurrent liabilities, other accrued liabilities and accrued salaries and related benefits on our balance sheet. Profit Sharing Program

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Aircraft Purchase Commitments In 2020, we restructured our aircraft order books with Airbus and MHI RJ Aviation Group (manufacturer of CRJ aircraft) in an effort to better match the timing of aircraft deliveries with our network and financial needs over the next several years. The restructuring reduced our aircraft purchase commitments by more than $2 billion in 2020 and by more than $5 billion through 2022. The shift in delivery timing is intended to allow us to continue simplifying and modernizing our fleet while maintaining our Airbus order book. Our future aircraft purchase commitments totaled approximately $13.9 billion at December 31, 2020: Aircraft purchase commitments (in millions) Total 2021 $ 1,330 2022 2,470 2023 2,310 2024 2,960 2025 2,740 Thereafter 2,070 Total $ 13,880 Our future aircraft purchase commitments included the following aircraft at December 31, 2020: Aircraft purchase commitments by fleet type Fleet Type Purchase Commitments A220-100 7 A220-300 45 A321-200 22 A321-200neo 100 A330-900neo (1) 29 A350-900 20 CRJ-900 1 Total 224 (1) Includes one A330-900neo lease commitment in 2021 incremental to our order book with Airbus. LATAM A350 Commitments We have assumed 10 of LATAM's A350 purchase commitments from Airbus, with deliveries through 2025, which are included as purchase commitments in the above table. We had agreed to acquire four A350 aircraft from LATAM, but terminated the purchase agreement for a fee of $62 million during the June 2020 quarter. See Note 5, "Investments," for further information on our strategic alliance with LATAM. Contract Carrier Agreements We have contract carrier agreements with regional carriers expiring from 2021 to 2029. Capacity Purchase Agreements . Our regional carriers primarily operate for us under capacity purchase agreements. Under these agreements, the regional carriers operate some or all of their aircraft using our flight designator codes, and we control the scheduling, pricing, reservations, ticketing and seat inventories of those aircraft and retain the revenues associated with those flights. We pay those airlines an amount, as defined in the applicable agreement, which is based on a determination of their cost of operating those flights and other factors intended to approximate market rates for those services. The following table shows our minimum obligations under our existing capacity purchase agreements with third-party regional carriers. The obligations set forth in the table contemplate minimum levels of flying by the regional carriers under the respective agreements and also reflect assumptions regarding certain costs associated with the minimum levels of flying such as the cost of fuel, labor, maintenance, insurance, catering, property tax and landing fees. Accordingly, our actual payments under these agreements could differ materially from the minimum fixed obligations set forth in the table below. Contract carrier minimum obligations (in millions) Amount (1) 2021 $ 1,413 2022 1,372 2023 1,240 2024 1,209 2025 837 Thereafter 1,654 Total $ 7,725 (1) These amounts exclude contract carrier payments accounted for as operating leases of aircraft, which are described in Note 9, "Leases." Revenue Proration Agreement . As of December 31, 2020, a portion of our contract carrier arrangement with SkyWest Airlines, Inc. was structured as a revenue proration agreement. This revenue proration agreement establishes a fixed dollar or percentage division of revenues for tickets sold to passengers traveling on connecting flight itineraries. Legal Contingencies We are involved in various legal proceedings related to employment practices, environmental issues, antitrust matters and other matters concerning our business. We record liabilities for losses from legal proceedings when we determine that it is probable that the outcome in a legal proceeding will be unfavorable and the amount of loss can be reasonably estimated. Although the outcome of the legal proceedings in which we are involved cannot be predicted with certainty, we believe that the resolution of current matters will not have a material adverse effect on our Consolidated Financial Statements. Credit Card Processing Agreements Our VISA/MasterCard and American Express credit card processing agreements provide that no cash reserve ("Reserve") is required, and no withholding of payment related to receivables collected will occur, except in certain circumstances, including when we do not maintain a required level of liquidity as outlined in the merchant processing agreements. In circumstances in which the credit card processor can establish a Reserve or withhold payments, the amount of the Reserve or payments that may be withheld would be equal to the potential liability of the credit card processor for tickets purchased with VISA/MasterCard or American Express credit cards, as applicable, that had not yet been used for travel. We did not have a Reserve or an amount withheld as of December 31, 2020 or 2019. Other Contingencies General Indemnifications We are the lessee under many commercial real estate leases. It is common in these transactions for us, as the lessee, to agree to indemnify the lessor and the lessor's related parties for tort, environmental and other liabilities that arise out of or relate to our use or occupancy of the leased premises. This type of indemnity would typically make us responsible to indemnified parties for liabilities arising out of the conduct of, among others, contractors, licensees and invitees at, or in connection with, the use or occupancy of the leased premises. This indemnity often extends to related liabilities arising from the negligence of the indemnified parties, but usually excludes any liabilities caused by either their sole or gross negligence or their willful misconduct. Our aircraft and other equipment lease and financing agreements typically contain provisions requiring us, as the lessee or obligor, to indemnify the other parties to those agreements, including certain of those parties' related persons, against virtually any liabilities that might arise from the use or operation of the aircraft or other equipment. We believe that our insurance would cover most of our exposure to liabilities and related indemnities associated with the commercial real estate leases and aircraft and other equipment lease and financing agreements described above. While our insurance does not typically cover environmental liabilities, we have insurance policies in place as required by applicable environmental laws. Some of our aircraft and other financing transactions include provisions that require us to make payments to preserve an expected economic return to the lenders if that economic return is diminished due to specified changes in law or regulations. In some of these financing transactions, we also bear the risk of changes in tax laws that would subject payments to non-U.S. lenders to withholding taxes. We cannot reasonably estimate our potential future payments under the indemnities and related provisions described above because we cannot predict (1) when and under what circumstances these provisions may be triggered and (2) the amount that would be payable if the provisions were triggered because the amounts would be based on facts and circumstances existing at such time. Employees Under Collective Bargaining Agreements As of December 31, 2020, we had approximately 74,000 full-time equivalent employees, 23% of whom were represented by unions. The following table shows our domestic airline employee groups that are represented by unions. Domestic airline employees represented by collective bargaining agreements by group Employee Group Approximate Number of Active Employees Represented Union Date on which Collective Bargaining Agreement Becomes Amendable Delta Pilots 12,940 ALPA December 31, 2019 Delta Flight Superintendents (Dispatchers) 350 PAFCA November 1, 2024 Endeavor Air Pilots 1,900 ALPA January 1, 2024 Endeavor Air Flight Attendants 1,480 AFA March 31, 2025 We are in mediated discussions with the representative of the Delta pilots regarding terms of their amendable collective bargaining agreement under the auspices of the National Mediation Board ("NMB"). In addition to the domestic airline employee groups discussed above, approximately 190 refinery employees of Monroe are represented by the United Steel Workers under an agreement that expires on February 28, 2022. This agreement is governed by the National Labor Relations Act, which generally allows either party to engage in self-help upon the expiration of the agreement. Certain of our employees outside the U.S. are represented by unions, work councils or other local representative groups. Other We have certain contracts for goods and services that require us to pay a penalty, acquire inventory specific to us or purchase contract-specific equipment, as defined by each respective contract, if we terminate the contract without cause prior to its expiration date. Because these obligations are contingent on our termination of the contract without cause prior to its expiration date, no obligation would exist unless such a termination occurs.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Income Tax Provision Our income tax provision consisted of the following: Components of income tax benefit (provision) Year Ended December 31, (in millions) 2020 2019 2018 Current tax benefit (provision): Federal $ 94 $ 94 $ 187 State and local 3 (39) (26) International (5) (13) (13) Deferred tax benefit (provision): Federal 2,766 (1,343) (1,226) State and local 344 (130) (138) Income tax benefit (provision) $ 3,202 $ (1,431) $ (1,216) The following table presents the principal reasons for the difference between the effective tax rate and the U.S. federal statutory income tax rate: Reconciliation of statutory federal income tax rate to the effective income tax rate Year Ended December 31, 2020 2019 2018 U.S. federal statutory income tax rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 1.9 2.3 2.5 Valuation allowance (2.6) 0.7 — Other 0.2 (0.9) 0.1 Effective income tax rate 20.5 % 23.1 % 23.6 % Deferred Taxes Deferred income taxes reflect the net tax effect of temporary differences between the carrying amounts of assets and liabilities for financial reporting and income tax purposes. The following table shows significant components of our deferred tax assets and liabilities: Significant components of deferred income tax assets and liabilities December 31, (in millions) 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 1,495 $ 560 Capital loss carryforward 483 — Pension, postretirement and other benefits 2,956 2,241 Deferred revenue 1,797 1,667 Lease liabilities 2,185 1,510 Other 611 380 Valuation allowance (460) (58) Total deferred tax assets $ 9,067 $ 6,300 Deferred tax liabilities: Depreciation $ 4,507 $ 5,190 Operating lease assets 1,324 1,298 Intangible assets 1,076 1,049 Other 172 99 Total deferred tax liabilities $ 7,079 $ 7,636 Net deferred tax assets (liabilities) (1) $ 1,988 $ (1,336) (1) At December 31, 2020, the net deferred tax assets of $2.0 billion are recorded in deferred income taxes, net within noncurrent assets. At December 31, 2019, the net deferred tax liabilities of $1.3 billion included $120 million of net state deferred tax assets, which are recorded in deferred income taxes, net within noncurrent assets, and $1.5 billion of net federal deferred tax liabilities, which are recorded in deferred income taxes, net within noncurrent liabilities. As of December 31, 2020, w e had $5.7 billion of federal pre-tax net operating loss carryforwards, which will not begin to expire until 2027. Valuation Allowance We periodically assess whether it is more likely than not that we will generate sufficient taxable income to realize our deferred income tax assets. We establish valuation allowances if it is not likely we will realize our deferred income tax assets. In making this determination, we consider available positive and negative evidence and make certain assumptions. We consider, among other things, projected future taxable income, scheduled reversals of deferred tax liabilities, the overall business environment, our historical financial results and tax planning strategies. At December 31, 2020 our net deferred tax asset balance was $2.0 billion, including a $460 million valuation allowance primarily related to capital loss carryforwards and state net operating losses. Although we are in a three year cumulative loss position as of December 31, 2020, we have a recent history of significant earnings prior to the onset of the COVID-19 pandemic. We expect to return to profitability as the effects of the pandemic subside and to generate sufficient taxable income to utilize our federal net operating loss carryforwards before any expire. Our federal net operating loss carryforwards generated before 2018 do not begin to expire until 2027. Under current tax law, federal net operating losses generated in 2020 do not expire. Therefore, we have not recorded a valuation allowance on our deferred tax assets other than the capital loss carryforwards and state net operating losses that have short expiration periods. Income Tax Allocation We consider all income sources, including other comprehensive income, in determining the amount of tax benefit allocated to continuing operations ("Income Tax Allocation"). The 2017 tax reform reduced the statutory tax rate in the U.S. from 35% to 21%. GAAP requires that the tax expense related to tax law changes be recognized in current earnings, even when a portion of the related deferred tax asset originated through amounts recognized in AOCI. As a result, approximately $750 million of income tax expense remains in AOCI, primarily related to pension obligations, and will not be recognized in net income until the pension obligations are fully extinguished. Other The amount of, and changes to, our uncertain tax positions were not material in any of the years presented. We are currently under audit by the IRS for the 2020 and 2019 tax years.

Equity and Equity Compensation

Equity and Equity Compensation	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Equity and Equity Compensation	EQUITY AND EQUITY COMPENSATION Equity We are authorized to issue 2.0 billion shares of capital stock, of which up to 1.5 billion may be shares of common stock, par value $0.0001 per share, and up to 500 million may be shares of preferred stock. Preferred Stock. We may issue preferred stock in one or more series. The Board of Directors is authorized (1) to fix the descriptions, powers (including voting powers), preferences, rights, qualifications, limitations and restrictions with respect to any series of preferred stock and (2) to specify the number of shares of any series of preferred stock. We have not issued any preferred stock. Treasury Stock. We generally withhold shares of Delta common stock to cover employees' portion of required tax withholdings when employee equity awards are issued or vest. These shares are valued at cost, which equals the market price of the common stock on the date of issuance or vesting. The weighted average cost per share held in treasury was $28.23 and $26.37 as of December 31, 2020 and 2019, respectively. Warrants. See Note 2, "Impact of the COVID-19 Pandemic," for further discussion of the warrants issued during 2020 in connection with the payroll support program of the CARES Act to acquire more than 6.7 million of Delta common stock. Equity Compensation Our broad-based equity and cash compensation plan provides for grants of restricted stock, stock options, performance awards, including cash incentive awards and other equity-based awards (the "Plan"). Shares of common stock issued under the Plan may be made available from authorized, but unissued, common stock or common stock we acquire. If any shares of our common stock are covered by an award that expires, is canceled, forfeited or otherwise terminates without delivery of shares (including shares surrendered or withheld for payment of taxes related to an award), such shares will again be available for issuance under the Plan except for (1) any shares tendered in payment of an option, (2) shares withheld to satisfy any tax withholding obligation with respect to the exercise of an option or stock appreciation right ("SAR") or (3) shares covered by a stock-settled SAR or other awards that were not issued upon the settlement of the award. The Plan authorizes the issuance of up to 163 million shares of common stock. As of December 31, 2020, there were 21 million shares available for future grants. We make long-term incentive awards annually to eligible employees under the Plan. Generally, awards vest over time, subject to the employee's continued employment. Equity compensation expense, including awards payable in common stock or cash, is recognized in salaries and related costs over the employee's requisite service period (generally, the vesting period of the award) and totaled $119 million, $161 million and $159 million for the years ended December 31, 2020, 2019 and 2018, respectively. We record expense on a straight-line basis for awards with installment vesting. As of December 31, 2020, unrecognized costs related to unvested shares and stock options totaled $80 million. We expect substantially all unvested awards to vest and recognize forfeitures as they occur. Restricted Stock . Restricted stock is common stock that may not be sold or otherwise transferred for a period of time and is subject to forfeiture in certain circumstances. The fair value of restricted stock awards is based on the closing price of the common stock on the grant date. As of December 31, 2020, there were 2.2 million unvested restricted stock awards. Stock Options. Stock options are granted with an exercise price equal to the closing price of Delta common stock on the grant date and generally have a 10-year term. We determine the fair value of stock options at the grant date using an option pricing model. As of December 31, 2020, there were 5.4 million outstanding stock option awards with a weighted average exercise price of $52.37 of which 2.4 million were exercisable. Performance Awards. Performance awards are long-term incentive opportunities, which are payable in common stock or cash, and are generally contingent upon our achieving certain financial goals. Other. During each of 2020 and 2019, we recognized an immaterial amount of excess tax benefits in our income tax provision.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Loss	ACCUMULATED OTHER COMPREHENSIVE LOSS The following table shows the components of accumulated other comprehensive loss: Components of accumulated other comprehensive loss (in millions) Pension and Other Benefits Liabilities (2) Other (3) Available-for-Sale Investment s (4) Total Balance at January 1, 2018 (net of tax effect of $1,400) $ (7,812) $ 85 $ 106 $ (7,621) Changes in value (net of tax effect of $88) (294) 7 — (287) Reclassifications into retained earnings (net of tax effect of $61) — — (106) (106) Reclassifications into earnings (net of tax effect of $57) (1) 181 8 — 189 Balance at December 31, 2018 (net of tax effect of $1,492) (7,925) 100 — (7,825) Changes in value (net of tax effect of $133) (422) 7 — (415) Reclassifications into earnings (net of tax effect of $76) (1) 252 (1) — 251 Balance at December 31, 2019 (net of tax effect $1,549) (8,095) 106 — (7,989) Changes in value (net of tax effect of $384) (1,269) 17 — (1,252) Reclassifications into earnings (net of tax effect of $169) (1) 286 (83) — 203 Balance at December 31, 2020 (net of tax effect of $1,764) $ (9,078) $ 40 $ — $ (9,038) (1) Amounts reclassified from AOCI for pension and other benefits liabilities are recorded in miscellaneous, net in non-operating expense in the income statement. (2) Includes approximately $750 million of deferred income tax expense primarily related to pension and other benefit obligations that will not be recognized in net income until these obligations are fully extinguished. We consider all income sources, including other comprehensive income, in determining the amount of tax benefit allocated to results from operations. (3) In the June 2020 quarter, all remaining foreign currency hedges expired, and we recognized an $83 million tax benefit which was released from AOCI. (4) The 2018 reclassification into retained earnings related to our investments in GOL, China Eastern and other previously designated available-for-sale investments, and the related conversion to accounting for changes in fair value of these investments from AOCI to the income statement.

Segments

Segments	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Segments	SEGMENTS Operating segments are defined as components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision maker and is used in resource allocation and performance assessments. Our chief operating decision maker is considered to be our executive leadership team. Our executive leadership team regularly reviews discrete information for our two operating segments, which are determined by the products and services provided: our airline segment and our refinery segment. Airline Segment Our airline segment is managed as a single business unit that provides scheduled air transportation for passengers and cargo throughout the U.S. and around the world and includes our loyalty program, as well as other ancillary airline services. This allows us to benefit from an integrated revenue pricing and route network. Our flight equipment forms one fleet, which is deployed through a single route scheduling system. When making resource allocation decisions, our chief operating decision maker evaluates flight profitability data, which considers fleet type and route economics, but gives no weight to the financial impact of the resource allocation decision on a geographic region or mainline/regional carrier basis. Our objective in making resource allocation decisions is to optimize our consolidated financial results. Refinery Segment Our wholly owned subsidiaries, Monroe Energy, LLC, and MIPC, LLC (collectively, "Monroe"), operate the Trainer oil refinery and related assets located near Philadelphia, Pennsylvania, as part of our strategy to mitigate the cost of the refining margin reflected in the price of jet fuel. Monroe's operations include pipelines and terminal assets that allow the refinery to supply jet fuel to our airline operations throughout the Northeastern U.S., including our New York hubs at LaGuardia and JFK. Our refinery segment operates for the benefit of the airline segment by providing jet fuel to the airline segment from its own production and through jet fuel obtained through agreements with third parties. The refinery's production consists of jet fuel, as well as non-jet fuel products. We use several counterparties to exchange the non-jet fuel products produced by the refinery for jet fuel consumed in our airline operations. The gross fair value of the products exchanged under these agreements during the years ended December 31, 2020, 2019 and 2018 was $1.5 billion, $4.0 billion and $3.6 billion, respectively. The decline in exchange transactions was primarily driven by the decrease in demand for jet fuel from our airline operations as a result of the economic conditions caused by the COVID-19 pandemic. Segment Reporting Segment results are prepared based on our internal accounting methods described below, with reconciliations to consolidated amounts in accordance with GAAP. Our segments are not designed to measure operating income or loss directly related to the products and services included in each segment on a stand-alone basis. Financial information by segment (in millions) Airline Refinery Intersegment Sales/Other Consolidated Year Ended December 31, 2020 Operating revenue: $ 15,945 $ 3,143 $ 17,095 Sales to airline segment $ (214) (1) Exchanged products (1,472) (2) Sales of refined products (307) (3) Operating loss (4) (12,253) (216) (12,469) Interest expense, net 928 1 929 Depreciation and amortization 2,312 99 (99) (4) 2,312 Restructuring charges 8,219 — 8,219 Total assets, end of period 70,548 1,448 71,996 Capital expenditures 1,879 20 1,899 Year Ended December 31, 2019 Operating revenue: $ 46,910 $ 5,558 $ 47,007 Sales to airline segment $ (1,103) (1) Exchanged products (3,963) (2) Sales of refined products (395) (3) Operating income (4) 6,542 76 6,618 Interest expense (income), net 327 (26) 301 Depreciation and amortization 2,581 99 (99) (4) 2,581 Total assets, end of period 62,793 1,739 64,532 Capital expenditures 4,880 56 4,936 Year Ended December 31, 2018 Operating revenue: $ 43,890 $ 5,458 $ 44,438 Sales to airline segment $ (962) (1) Exchanged products (3,596) (2) Sales of refined products (352) (3) Operating income (4) 5,206 58 5,264 Interest expense (income), net 334 (23) 311 Depreciation and amortization 2,329 67 (67) (4) 2,329 Total assets, end of period 58,561 1,705 60,266 Capital expenditures 5,005 163 5,168 (1) Represents transfers, valued on a market price basis, from the refinery to the airline segment for use in airline operations. We determine market price by reference to the market index for the primary delivery location, which is New York Harbor, for jet fuel from the refinery. (2) Represents value of products delivered under our exchange agreements, as discussed above, determined on a market price basis. (3) These sales were at or near cost; accordingly, the margin on these sales is de minimis. (4) Refinery segment operating results, including depreciation and amortization, are included within aircraft fuel and related taxes in our income statement.

(Loss)_Earnings Per Share

(Loss)/Earnings Per Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
(Loss)/Earnings Per Share	(LOSS)/EARNINGS PER SHARE We calculate basic (loss)/earnings per share and diluted (loss) per share by dividing net (loss)/income by the weighted average number of common shares outstanding, excluding restricted shares. We calculate diluted earnings per share by dividing net income by the weighted average number of common shares outstanding plus the dilutive effect of outstanding share-based awards, including stock options and restricted stock awards. Antidilutive common stock equivalents excluded from the diluted (loss)/earnings per share calculation are not material. The following table shows our computation of basic and diluted (loss)/earnings per share: Basic and diluted (loss)/earnings per share Year Ended December 31, (in millions, except per share data) 2020 2019 2018 Net (loss)/income $ (12,385) $ 4,767 $ 3,935 Basic weighted average shares outstanding 636 651 691 Dilutive effect of share-based awards — 2 3 Diluted weighted average shares outstanding 636 653 694 Basic (loss)/earnings per share $ (19.49) $ 7.32 $ 5.69 Diluted (loss)/earnings per share $ (19.49) $ 7.30 $ 5.67

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Delta Air Lines, Inc., a Delaware corporation, provides scheduled air transportation for passengers and cargo throughout the United States ("U.S.") and around the world. Our Consolidated Financial Statements include the accounts of Delta Air Lines, Inc. and our consolidated subsidiaries and have been prepared in accordance with accounting principles generally accepted in the U.S. ("GAAP"). We are the primary beneficiary of, and have a controlling financial interest in, certain immaterial entities in which we have voting rights of 50% or less, which we consolidate in our financial results. We have marketing alliances with other airlines to enhance our access to domestic and international markets. These arrangements may include codesharing, reciprocal loyalty program benefits, shared or reciprocal access to passenger lounges, joint promotions, common use of airport gates and ticket counters, ticket office co-location and other marketing agreements. We have received antitrust immunity for certain marketing arrangements, which enables us to offer a more integrated route network and develop common sales, marketing and discount programs for customers. Some of our marketing arrangements provide for the sharing of revenues and expenses. Revenues and expenses associated with collaborative arrangements are presented on a gross basis in the applicable line items on our Consolidated Statements of Operations ("income statement"). We have reclassified certain prior period amounts to conform to the current period presentation. Unless otherwise noted, all amounts disclosed are stated before consideration of income taxes.
Use of Estimates	Use of Estimates We are required to make estimates and assumptions when preparing our Consolidated Financial Statements in accordance with GAAP. These estimates and assumptions affect the amounts reported in our Consolidated Financial Statements and the accompanying notes. Actual results could differ materially from those estimates.
Recent Accounting Standards	Recent Accounting Standards Credit Losses. In 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-13, "Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments." Under this ASU, an entity is required to utilize an "expected credit loss model" on certain financial instruments, including trade and financing receivables. This model requires consideration of a broader range of reasonable and supportable information and requires an entity to estimate expected credit losses over the lifetime of the asset. We adopted this standard effective January 1, 2020 and due to the COVID-19 pandemic, we recorded reserves on certain receivables, which are discussed further in Note 5, "Investments."
Cash and Cash Equivalents	Short-term, highly liquid investments with maturities of three months or less when purchased are classified as cash and cash equivalents.
Short-Term Investments	Investments with maturities of greater than three months, but not in excess of one year, when purchased are classified as short-term investments. Investments with maturities beyond one year when purchased may be classified as short-term investments if they are expected to be available to support our short-term liquidity needs. Our short-term investments were classified as fair value investments and gains and losses were recorded in non-operating expense.
Inventories	Inventories Fuel. As part of our strategy to mitigate the cost of the refining margin reflected in the price of jet fuel, our wholly owned subsidiaries, Monroe Energy, LLC and MIPC, LLC (collectively, "Monroe"), operate the Trainer oil refinery. Refined product, feedstock and blendstock inventories, all of which are finished goods, are carried at recoverable cost. We use jet fuel in our airline operations that is produced by the refinery and procured through the exchange with third parties of gasoline, diesel and other refined products ("non-jet fuel products") the refinery produces. Cost is determined using the first-in, first-out method. Costs include the raw material consumed plus direct manufacturing costs (such as labor, utilities and supplies) incurred and an applicable portion of manufacturing overhead. Expendables Parts and Supplies. Inventories of expendable parts related to flight equipment, which cannot be economically repaired, reconditioned or reused after removal from the aircraft, are carried at moving average cost and charged to operations as consumed. An allowance for obsolescence is provided over the remaining useful life of the related fleet. We also provide allowances for parts identified as excess or obsolete to reduce the carrying costs to the lower of cost or net realizable value. These parts are assumed to have an estimated residual value of 5% of the original cost.
Accounting for Refinery Related Buy/Sell Agreements	Accounting for Refinery Related Buy/Sell Agreements To the extent that we receive jet fuel for non-jet fuel products exchanged under buy/sell agreements, we account for these transactions as nonmonetary exchanges. We have recorded these nonmonetary exchanges at the carrying amount of the non-jet fuel products transferred within aircraft fuel and related taxes on the income statement.
Derivatives	Derivatives Changes in fuel prices, interest rates and foreign currency exchange rates impact our results of operations. In an effort to manage our exposure to these risks, we may enter into derivative contracts and adjust our derivative portfolio as market conditions change. We recognize derivative contracts at fair value on our balance sheets. The following table summarizes the risk hedged and the classification of related gains and losses in our income statement, by each type of derivative contract: Derivative Type Hedged Risk Classification of Gains and Losses Fuel hedge contracts Fluctuations in fuel prices Aircraft fuel and related taxes Interest rate contracts Increases in interest rates Interest expense, net Foreign currency exchange contracts Fluctuations in foreign currency exchange rates Non-operating expense The following table summarizes the accounting treatment of our derivative contracts: Accounting Designation Impact of Unrealized Gains and Losses Not designated as hedges Change in fair value (1) of hedge is recorded in earnings Designated as cash flow hedges Market adjustments are recorded in Accumulated Other Comprehensive Income ("AOCI") Designated as fair value hedges Market adjustments are recorded in debt and finance leases (1) Including settled gains and losses as well as mark-to-market adjustments ("MTM adjustments"). We perform, at least quarterly, an assessment of the effectiveness of our derivative contracts designated as hedges, including assessing the possibility of counterparty default. If we determine that a derivative is no longer expected to be highly effective, we discontinue hedge accounting prospectively and recognize subsequent changes in the fair value of the hedge in earnings. We believe our derivative contracts that continue to be designated as hedges, consisting of interest rate exchange contracts, will continue to be highly effective in offsetting changes in fair value attributable to the hedged risk. Cash flows associated with purchasing and settling hedge contracts generally are classified as operating cash flows. However, if a hedge contract includes a significant financing element at inception, cash flows associated with the hedge contract are recorded as financing cash flows. Hedge Margin. The hedge margin we receive from counterparties is recorded in cash, with the offsetting obligation in accounts payable. The hedge margin we provide to counterparties is recorded in prepaid expenses and other. We do not offset margin funded to counterparties or margin funded to us by counterparties against fair value amounts recorded for our hedge contracts.
Property and Equipment, net	Property and Equipment, net Our flight equipment, which consists of aircraft and associated engines and parts, and other long-lived assets, which are classified as property and equipment, net on our balance sheet, have a recorded value of $26.5 billion at December 31, 2020. The following table summarizes our property and equipment: Property and equipment by classification December 31, (in millions, except for estimated useful life) Estimated Useful Life 2020 2019 Flight equipment 20-34 years $ 31,572 $ 36,713 Ground property and equipment 3-40 years 6,387 5,721 Information technology-related assets 3-15 years 3,403 3,276 Flight and ground equipment under finance leases Shorter of lease term or estimated useful life 1,795 1,608 Advance payments for equipment 883 1,019 Less: accumulated depreciation and amortization (1) (17,511) (17,027) Total property and equipment, net $ 26,529 $ 31,310 (1) Includes accumulated amortization for flight and ground equipment under finance leases in the amount of $793 million and $546 million at December 31, 2020 and 2019, respectively. three ten
Impairment of Long-Lived Assets	We review flight equipment and other long-lived assets used in operations for impairment losses when events and circumstances indicate the assets may be impaired. Factors which could be indicators of impairment include, but are not limited to (1) a decision to permanently remove flight equipment or other long-lived assets from operations, (2) significant changes in the estimated useful life, (3) significant changes in projected cash flows, (4) permanent and significant declines in fleet fair values and (5) changes to the regulatory environment. For long-lived assets held for sale, we discontinue depreciation and record impairment losses when the carrying amount of these assets is greater than the fair value less the cost to sell. See Note 2, "Impact of the COVID-19 Pandemic," for information on impairments and related charges recorded during 2020. To determine whether impairments exist for active and temporarily parked aircraft, we group assets at the fleet type level or at the contract level for aircraft operated by third-party regional carriers (i.e., the lowest level for which there are identifiable cash flows) and then estimate future cash flows based on projections of capacity, passenger mile yield, fuel and labor costs and other relevant factors. Given the substantial reduction in our active aircraft and diminished projections of future cash flows in the near term as a result of the COVID-19 pandemic, we evaluated our fleet during 2020 and determined that only the fleet types discussed in Note 2, "Impact of the COVID-19 Pandemic," were impaired, as the future cash flows from the operation of all other fleet types through the respective retirement dates exceeded the carrying value. As we obtain greater clarity about the duration and extent of reduced demand and potentially execute further capacity adjustments, we will continue to evaluate our fleet compared to network requirements and may decide to retire additional aircraft. Future decisions regarding the temporarily parked aircraft and the timing of any return to service will be dependent on the evolution of the demand environment.
Income Taxes	Income Taxes We account for deferred income taxes under the liability method. We recognize deferred tax assets and liabilities based on the tax effects of temporary differences between the financial statement and tax basis of assets and liabilities, as measured by current enacted tax rates. Deferred tax assets and liabilities are net by jurisdiction and are recorded as noncurrent on the balance sheet. We have elected to recognize earnings of foreign affiliates that are determined to be global intangible low tax income in the period it arises and do not recognize deferred taxes for basis differences that may reverse in future years. A valuation allowance is recorded to reduce deferred tax assets when necessary. We periodically assess whether it is more likely than not that we will generate sufficient taxable income to realize our deferred income tax assets. We establish valuation allowances if it is not likely we will realize our deferred income tax assets. In making this determination, we consider available positive and negative evidence and make certain assumptions. We consider, among other things, projected future taxable income, scheduled reversals of deferred tax liabilities, the overall business environment, our historical financial results and tax planning strategies. See Note 13, "Income Taxes," for further information on our deferred income taxes.
Fuel Card Obligation	Fuel Card ObligationWe have a purchasing card with American Express for the purpose of buying jet fuel and crude oil. The card carried a maximum credit limit of $1.1 billion as of December 31, 2020 and must be paid monthly.
Retirement of Repurchased Shares	Retirement of Repurchased Shares We immediately retire shares repurchased pursuant to any share repurchase program. We allocate the share purchase price in excess of par value between additional paid-in capital and retained earnings.
Manufacturers' Credits	Manufacturers' Credits We periodically receive credits in connection with the acquisition of aircraft and engines. These credits are deferred until the aircraft and engines are delivered, and then applied as a reduction to the cost of the related equipment.
Maintenance Costs	Maintenance Costs We record maintenance costs related to our fleet in aircraft maintenance materials and outside repairs. Maintenance costs are expensed as incurred, except for costs incurred under power-by-the-hour contracts, which are expensed based on actual hours flown. Power-by-the-hour contracts transfer certain risk to third-party service providers and fix the amount we pay per flight hour to the service provider in exchange for maintenance and repairs under a predefined maintenance program. Modifications that enhance the operating performance or extend the useful lives of airframes or engines are capitalized and amortized over the remaining estimated useful life of the asset or the remaining lease term, whichever is shorter.
Advertising Costs	Advertising CostsWe expense advertising costs in passenger commissions and other selling expenses in the year the advertising first takes place.
Commissions and Merchant Fees	Commissions and Merchant Fees Passenger sales commissions and merchant fees are recognized in operating expense when the related revenue is recognized.
Goodwill and Indefinite-Live Intangible Assets	Goodwill and Indefinite-Lived Intangible Assets Our goodwill and identifiable intangible assets relate to the airline segment. We apply a fair value-based impairment test to the carrying value of goodwill and indefinite-lived intangible assets on an annual basis (as of October 1) and, if certain events or circumstances indicate that an impairment loss may have been incurred, on an interim basis. We assess the value of our goodwill and indefinite-lived assets under either a qualitative or quantitative approach. Under a qualitative approach, we consider various market factors, including certain of the key assumptions listed below. We analyze these factors to determine if events and circumstances have affected the fair value of goodwill and indefinite-lived intangible assets. If we determine that it is more likely than not that the asset may be impaired, we use the quantitative approach to assess the asset's fair value and the amount of the impairment. Under a quantitative approach, we calculate the fair value of the asset incorporating the key assumptions listed below into our calculation. We value goodwill and indefinite-lived intangible assets primarily using market and income approach valuation techniques. These measurements include the following key assumptions (1) forecasted revenues, expenses and cash flows, including the duration and extent of impact to our business and our alliance partners from the COVID-19 pandemic, (2) current discount rates, (3) observable market transactions and (4) anticipated changes to the regulatory environment (e.g., diminished slot access, additional Open Skies agreements or changes to antitrust approvals). These assumptions are consistent with those that hypothetical market participants would use. Because we are required to make estimates and assumptions when evaluating goodwill and indefinite-lived intangible assets for impairment, actual transaction amounts may differ materially from these estimates. We recognize an impairment charge if the asset's carrying value exceeds its estimated fair value. Changes in certain events and circumstances could result in impairment or a change from indefinite-lived to definite-lived. Factors which could cause impairment include, but are not limited to (1) negative trends in our market capitalization, (2) reduced profitability resulting from lower passenger mile yields or higher input costs (primarily related to fuel and employees), (3) lower passenger demand as a result of weakened U.S. and global economies, global pandemics or other factors, (4) interruption to our operations due to a prolonged employee strike, terrorist attack or other reasons, (5) changes to the regulatory environment (e.g., diminished slot access, additional Open Skies agreements or changes to antitrust approvals), (6) competitive changes by other airlines and (7) strategic changes to our operations leading to diminished utilization of the intangible assets. Identifiable Intangible Assets. Indefinite-lived assets are not amortized and consist of routes, slots, the Delta tradename and assets related to alliances and collaborative arrangements. Definite-lived intangible assets consist primarily of marketing and maintenance service agreements and are amortized on a straight-line basis or under the undiscounted cash flows method over the estimated economic life of the respective agreements. Costs incurred to renew or extend the term of an intangible asset are expensed as incurred.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Reconciliation of cash, cash equivalents, and restricted cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the Consolidated Balance Sheets ("balance sheets") that sum to the total of the same such amounts shown within the Consolidated Statements of Cash Flows ("cash flows statement"). Reconciliation of cash, cash equivalents and restricted cash Year Ended December 31, (in millions) 2020 2019 2018 Current assets: Cash and cash equivalents $ 8,307 $ 2,882 $ 1,565 Restricted cash included in prepaid expenses and other 192 212 47 Noncurrent assets: Cash restricted for airport construction 1,556 636 1,136 Total cash, cash equivalents and restricted cash $ 10,055 $ 3,730 $ 2,748
Schedule of information related to derivative contracts	The following table summarizes the risk hedged and the classification of related gains and losses in our income statement, by each type of derivative contract: Derivative Type Hedged Risk Classification of Gains and Losses Fuel hedge contracts Fluctuations in fuel prices Aircraft fuel and related taxes Interest rate contracts Increases in interest rates Interest expense, net Foreign currency exchange contracts Fluctuations in foreign currency exchange rates Non-operating expense The following table summarizes the accounting treatment of our derivative contracts: Accounting Designation Impact of Unrealized Gains and Losses Not designated as hedges Change in fair value (1) of hedge is recorded in earnings Designated as cash flow hedges Market adjustments are recorded in Accumulated Other Comprehensive Income ("AOCI") Designated as fair value hedges Market adjustments are recorded in debt and finance leases (1) Including settled gains and losses as well as mark-to-market adjustments ("MTM adjustments").
Summary of property and equipment by classification	The following table summarizes our property and equipment: Property and equipment by classification December 31, (in millions, except for estimated useful life) Estimated Useful Life 2020 2019 Flight equipment 20-34 years $ 31,572 $ 36,713 Ground property and equipment 3-40 years 6,387 5,721 Information technology-related assets 3-15 years 3,403 3,276 Flight and ground equipment under finance leases Shorter of lease term or estimated useful life 1,795 1,608 Advance payments for equipment 883 1,019 Less: accumulated depreciation and amortization (1) (17,511) (17,027) Total property and equipment, net $ 26,529 $ 31,310 (1) Includes accumulated amortization for flight and ground equipment under finance leases in the amount of $793 million and $546 million at December 31, 2020 and 2019, respectively.

Impact of the COVID-19 Pandem_2

Impact of the COVID-19 Pandemic (Tables)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of restructuring charges by category	The restructuring charges incurred during 2020 as part of our response to the COVID-19 pandemic are summarized as follows: Restructuring charges by category (in millions) Year Ended Fleet Retirements $ 4,409 Voluntary Programs and Other Employee Benefit Charges 3,409 Receivables and Other 401 Total Restructuring Charges $ 8,219
Schedule of fleet retirements by aircraft type	As a result of the COVID-19 pandemic and our response, we have removed certain aircraft from active service as of December 31, 2020, which includes owned and leased aircraft that are being retired early. Fleet retirements by aircraft type Fleet Type Number of Aircraft Estimated Final Retirement During the Quarter Ended Impairment-Related Charge (in millions) 777 18 December 2020 $ 1,440 767-300ER 56 December 2025 1,084 717 91 December 2025 950 MD-90 26 June 2020 335 CRJ-200 (1) 125 December 2023 320 737-700 10 September 2020 223 A320 10 June 2020 57 MD-88 (2) 47 June 2020 — Total 383 $ 4,409 (1) Certain of the CRJ-200 aircraft scheduled to be retired by the December 2023 quarter are operated for us by SkyWest Airlines under a revenue proration agreement. (2) During the March 2020 quarter, we recorded a $22 million charge related to accelerating the planned retirement of the MD-88 fleet from December 2020 to June 2020. However, this amount was recorded in depreciation and amortization, rather than in restructuring charges, as it would have been incurred during 2020 prior to the onset of the COVID-19 pandemic.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Schedule of disaggregation of revenue	Passenger revenue is primarily composed of passenger ticket sales, loyalty travel awards and travel-related services performed in conjunction with a passenger’s flight. Passenger revenue by category Year Ended December 31, (in millions) 2020 2019 2018 Ticket $ 10,970 $ 36,908 $ 34,950 Loyalty travel awards 935 2,900 2,651 Travel-related services 978 2,469 2,154 Total passenger revenue $ 12,883 $ 42,277 $ 39,755 Other Revenue Year Ended December 31, (in millions) 2020 2019 2018 Ancillary businesses and refinery $ 1,798 $ 1,297 $ 1,801 Loyalty program 1,458 1,962 1,459 Miscellaneous 348 718 558 Total other revenue $ 3,604 $ 3,977 $ 3,818
Schedule loyalty program activity	The table below presents the activity of the current and noncurrent loyalty program deferred revenue, and includes miles earned through travel and miles sold to participating companies, which are primarily through marketing agreements. Loyalty program activity (in millions) 2020 2019 2018 Balance at January 1 $ 6,728 $ 6,641 $ 6,321 Miles earned 1,437 3,156 3,142 Travel miles redeemed (935) (2,900) (2,651) Non-travel miles redeemed (48) (169) (171) Balance at December 31 $ 7,182 $ 6,728 $ 6,641
Schedule of revenue by geographic region	Operating revenue for the airline segment is recognized in a specific geographic region based on the origin, flight path and destination of each flight segment. A significant portion of the refinery's revenues typically consists of fuel sales to support the airline, which is eliminated in the Consolidated Financial Statements. The remaining operating revenue for the refinery segment is included in the domestic region. Our passenger and operating revenue by geographic region is summarized in the following table: Revenue by geographic region Passenger Revenue Operating Revenue Year Ended December 31, Year Ended December 31, (in millions) 2020 2019 2018 2020 2019 2018 Domestic $ 10,041 $ 30,465 $ 28,235 $ 13,339 $ 33,382 $ 31,309 Atlantic 1,171 6,326 6,135 1,649 7,308 7,012 Latin America 1,113 2,985 2,864 1,321 3,326 3,157 Pacific 558 2,501 2,521 786 2,991 2,960 Total $ 12,883 $ 42,277 $ 39,755 $ 17,095 $ 47,007 $ 44,438

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of assets (liabilities) measured at fair value on a recurring basis	December 31, 2020 Valuation (in millions) Total Level 1 Level 2 Level 3 Cash equivalents $ 5,755 $ 5,755 $ — $ — (a) Restricted cash equivalents 1,747 1,747 — — (a) Short-term investments U.S. Government securities 5,789 3,919 1,870 — (a) Long-term investments 1,417 948 38 431 (a)(b) Hedge derivatives, net Fuel hedge contracts (9) — (9) — (a)(b) Interest rate contracts 23 — 23 — (a) Foreign currency exchange contracts (13) — (13) — (a) December 31, 2019 Valuation (in millions) Total Level 1 Level 2 Level 3 Cash equivalents $ 586 $ 586 $ — $ — (a) Restricted cash equivalents 847 847 — — (a) Long-term investments 1,099 881 33 185 (a)(b) Hedge derivatives, net Fuel hedge contracts 1 (1) 2 — (a)(b) Interest rate contracts 61 — 61 — (a) Foreign currency exchange contracts 6 — 6 — (a) (1) See Note 11, "Employee Benefit Plans," for fair value of benefit plan assets.

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Schedule of fair value investments ownership interest and carrying value	Our investments accounted for at fair value are summarized in the following table: Fair value investments ownership interest and carrying value Ownership Interest Carrying Value (in millions) December 31, 2020 December 31, 2019 December 31, 2020 December 31, 2019 Hanjin-KAL 13 % 10 % $ 512 $ 205 Air France-KLM 9 % 9 % 235 418 China Eastern 3 % 3 % 201 258 Other investments 469 218 Total fair value investments $ 1,417 $ 1,099
Schedule of equity method investments ownership interest and carrying value	We account for the investments listed below and certain other immaterial investments under the equity method of accounting. Equity method investments ownership interest and carrying value Ownership Interest Carrying Value (in millions) December 31, 2020 December 31, 2019 December 31, 2020 December 31, 2019 Virgin Atlantic (1) 49 % 49 % $ — $ 375 Unifi Aviation 49 % 49 % 154 142 (1) We have a non-controlling equity stake in Virgin Atlantic Limited, the parent company of Virgin Atlantic Airways, and similar non-controlling interests in certain affiliated Virgin Atlantic companies.

Derivatives and Risk Manageme_2

Derivatives and Risk Management (Tables)	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of hedge positions	Hedge Position as of December 31, 2020 (in millions) Volume Final Maturity Date Prepaid Expenses and Other Other Noncurrent Assets Other Accrued Liabilities Other Noncurrent Liabilities Hedge Derivatives, net Designated as hedges Interest rate contract (fair value hedges) 150 U.S. dollars April 2028 $ 3 $ 20 $ — $ — $ 23 Not designated as hedges Foreign currency exchange contract 177,045 South Korean won April 2023 — — — (13) (13) Fuel hedge contracts 157 gallons - crude oil and refined products April 2021 — — (9) — (9) Total derivative contracts $ 3 $ 20 $ (9) $ (13) $ 1 Hedge Position as of December 31, 2019 (in millions) Volume Final Maturity Date Prepaid Expenses and Other Other Noncurrent Assets Other Accrued Liabilities Other Noncurrent Liabilities Hedge Derivatives, net Designated as hedges Interest rate contracts (fair value hedges) 1,872 U.S. dollars April 2028 $ 12 $ 53 $ (4) $ — $ 61 Not designated as hedges Foreign currency exchange contract 397 Euros December 2020 9 — — — 9 Foreign currency exchange contract 177,045 South Korean won April 2023 1 — — (4) (3) Fuel hedge contracts 243 gallons - crude oil and refined products July 2020 16 — (15) — 1 Total derivative contracts $ 38 $ 53 $ (19) $ (4) $ 68
Schedule of balance sheet location of hedged items in fair value hedges	Balance sheet location of hedged item in fair value hedges Carrying Amount of Hedge Instruments Cumulative Amount of Fair Value Hedge Adjustments (1) (in millions) December 31, 2020 December 31, 2019 December 31, 2020 December 31, 2019 Current maturities of debt and finance leases $ 21 $ (19) $ 21 $ 8 Debt and finance leases (72) (1,783) 77 53 (1) As of December 31, 2020, these amounts include the cumulative amount of fair value hedging adjustments remaining for which hedge accounting has been discontinued of approximately $76 million.
Schedule of offsetting assets	The following table shows the net fair value of our counterparty positions had we elected to offset. Derivative contracts offsetting assets and liabilities (in millions) Prepaid Expenses and Other Other Noncurrent Assets Other Accrued Liabilities Other Noncurrent Liabilities Hedge Derivatives, Net December 31, 2020 Net derivative contracts $ 3 $ 20 $ (9) $ (13) $ 1 December 31, 2019 Net derivative contracts $ 24 $ 53 $ (5) $ (4) $ 68
Schedule of offsetting liabilities	The following table shows the net fair value of our counterparty positions had we elected to offset. Derivative contracts offsetting assets and liabilities (in millions) Prepaid Expenses and Other Other Noncurrent Assets Other Accrued Liabilities Other Noncurrent Liabilities Hedge Derivatives, Net December 31, 2020 Net derivative contracts $ 3 $ 20 $ (9) $ (13) $ 1 December 31, 2019 Net derivative contracts $ 24 $ 53 $ (5) $ (4) $ 68
Schedule of derivative gains (losses) by category	Not Designated Hedge Gains (Losses) Gains (losses) related to our foreign currency exchange and fuel contracts are as follows: Not designated hedge gains/(losses) by category Location of Gain (Loss) Recognized in Income Gain (Loss) Recognized in Income Year Ended December 31, (in millions) 2020 2019 2018 Foreign currency exchange contracts Gain/(loss) on investments, net $ (31) $ 10 $ (4) Fuel hedge contracts Aircraft fuel and related taxes 85 (41) 52 Total $ 54 $ (31) $ 48

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule goodwill and indefinite-lived intangible assets by category	Our December 2020 quarter quantitative impairment tests of goodwill and intangibles concluded that there was no indication of impairment as the fair value exceeded our carrying value: Goodwill and indefinite-lived intangible assets by category Carrying Value at Excess Fair Value at 2020 Testing Date (in millions) December 31, 2020 December 31, 2019 Goodwill (1) $ 9,753 $ 9,781 >100% International routes and slots 2,583 2,583 10% to 30% Airline alliances (2) 1,863 1,005 20% to >100% Delta tradename 850 850 >100% Domestic slots 622 622 60% to >100% Total $ 15,671 $ 14,841 (1) The reduction in goodwill relates to the combination of Delta Private Jets with Wheels Up in the March 2020 quart er. See Note 5, "Investments," for more information on this transaction. (2) As part of our strategic alliance with and investment in LATAM, we have recorded an alliance-related indefinite-lived intangible asset of $1.2 billion, which was not reflected in the December 31, 2019 balance.
Schedule of definite-lived intangible assets by category	Definite-Lived Intangible Assets Definite-lived intangible assets by category December 31, 2020 December 31, 2019 (in millions) Gross Gross Marketing agreements $ 730 $ (696) $ 730 $ (692) Contracts 193 (134) 193 (128) Other 53 (53) 53 (53) Total $ 976 $ (883) $ 976 $ (873)

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of outstanding debt by category	The following table summarizes our debt as of the dates indicated below: Summary of outstanding debt by category Maturity Interest Rate(s) Per Annum at December 31, (in millions) Dates December 31, 2020 2020 2019 Unsecured notes 2021 to 2029 2.90% to 7.38% $ 5,350 $ 5,550 Unsecured CARES Act Payroll Support Program Loan (1) 2030 1.00% 1,648 — Financing arrangements secured by SkyMiles assets: SkyMiles Notes (2) 2023 to 2028 4.50% and 4.75% 6,000 — SkyMiles Term Loan (2)(3) 2023 to 2027 4.75% 3,000 — Financing arrangements secured by slots, gates and/or routes: 2020 Senior Secured Notes 2025 7.00% 3,500 — 2020 Term Loan (2)(3) 2021 to 2023 5.75% 1,493 — 2018 Revolving Credit Facility (3) 2021 to 2023 Undrawn — — Financing arrangements secured by aircraft: Certificates (2) 2021 to 2028 2.00% to 8.02% 2,633 1,669 Notes (2)(3) 2021 to 2032 0.81% to 5.75% 1,284 1,193 NYTDC Special Facilities Revenue Bonds, Series 2020 (2) 2026 to 2045 4.00% to 5.00% 1,511 — NYTDC Special Facilities Revenue Bonds, Series 2018 (2) 2022 to 2036 4.00% to 5.00% 1,383 1,383 Other financings (2)(3) 2021 to 2030 2.51% to 8.75% 412 196 Other revolving credit facilities (3) 2021 to 2022 Undrawn — — Total secured and unsecured debt 28,214 9,991 Unamortized (discount)/premium and debt issuance cost, net and other (240) 115 Total debt 27,974 10,106 Less: current maturities (1,443) (2,054) Total long-term debt $ 26,531 $ 8,052 (1) See Note 2, "Impact of the COVID-19 Pandemic," for further discussion of the terms, including the applicable interest rate. (2) Due in installments.
Schedule of 2020-1 EETC issuance by class	The details of the 2020-1 EETC, which is secured by 33 aircraft, are shown in the table below: 2020-1 EETC issuance by class (in millions) Total Principal Fixed Interest Rate Issuance Date Final Maturity Date 2020-1 Class AA Certificates $ 796 2.00 % March 2020 June 2028 2020-1 Class A Certificates 204 2.50 % March 2020 June 2028 2020-1 Class B Certificates 135 8.00 % April 2020 June 2027 Total $ 1,135
Schedule of fair value of outstanding debt	The fair value of debt, shown below, is principally based on reported market values, recently completed market transactions and estimates based on interest rates, maturities, credit risk and underlying collateral. Debt is primarily classified as Level 2 within the fair value hierarchy. Fair value of outstanding debt (in millions) December 31, December 31, Net carrying amount $ 27,974 $ 10,106 Fair value $ 29,800 $ 10,400
Schedule of future debt maturities	The following table summarizes scheduled maturities of our debt for the years succeeding December 31, 2020: Future debt maturities Total Debt Amortization of 2021 $ 1,480 $ (62) 2022 1,882 (63) 2023 4,016 (54) 2024 3,126 (46) 2025 5,157 (23) Thereafter 12,553 8 Total $ 28,214 $ (240) $ 27,974

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Schedule of lease asset and liability balance sheet position by category	The table below presents the lease-related assets and liabilities recorded on the balance sheet. Lease asset and liability balance sheet position by category December 31, (in millions) Classification on the Balance Sheet 2020 2019 Assets Operating lease assets Operating lease right-of-use assets $ 5,733 $ 5,627 Finance lease assets Property and equipment, net 1,002 1,062 Total lease assets $ 6,735 $ 6,689 Liabilities Current Operating Current maturities of operating leases $ 678 $ 801 Finance Current maturities of debt and finance leases 289 233 Noncurrent Operating Noncurrent operating leases 5,713 5,294 Finance Debt and finance leases 894 821 Total lease liabilities $ 7,574 $ 7,149 Weighted-average remaining lease term Operating leases 12 years 12 years Finance leases 5 years 5 years Weighted-average discount rate Operating leases 4.88 % 3.73 % Finance leases 3.61 % 3.46 %
Schedule of lease cost by category	The table below presents certain information related to the lease costs for finance and operating leases. Lease cost by category Year Ended December 31, (in millions) 2020 2019 2018 Finance lease cost Amortization of leased assets $ 131 $ 110 $ 100 Interest of lease liabilities 32 29 22 Operating lease cost (1) 1,019 1,013 994 Short-term lease cost (1) 264 500 458 Variable lease cost (1) 1,406 1,456 1,427 Total lease cost $ 2,852 $ 3,108 $ 3,001
Schedule supplemental lease-related cash flow information	The table below presents supplemental cash flow information related to leases. Supplemental lease-related cash flow information Year Ended December 31, (in millions) 2020 2019 2018 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows for operating leases $ 1,053 $ 1,166 $ 1,271 Operating cash flows for finance leases 32 27 22 Financing cash flows for finance leases 255 192 108
Schedule of future cash flows and reconciliation to the balance sheet, operating leases	The table below reconciles the undiscounted cash flows for each of the first five years and total of the remaining years to the finance lease liabilities and operating lease liabilities recorded on the balance sheet. Future lease cash flows and reconciliation to the balance sheet (in millions) Operating Leases Finance Leases 2021 $ 949 $ 328 2022 848 238 2023 837 191 2024 770 266 2025 746 128 Thereafter 4,450 149 Total minimum lease payments 8,600 1,300 Less: amount of lease payments representing interest (2,209) (117) Present value of future minimum lease payments 6,391 1,183 Less: current obligations under leases (678) (289) Long-term lease obligations $ 5,713 $ 894
Schedule of future cash flows and reconciliation to the balance sheet, finance leases	The table below reconciles the undiscounted cash flows for each of the first five years and total of the remaining years to the finance lease liabilities and operating lease liabilities recorded on the balance sheet. Future lease cash flows and reconciliation to the balance sheet (in millions) Operating Leases Finance Leases 2021 $ 949 $ 328 2022 848 238 2023 837 191 2024 770 266 2025 746 128 Thereafter 4,450 149 Total minimum lease payments 8,600 1,300 Less: amount of lease payments representing interest (2,209) (117) Present value of future minimum lease payments 6,391 1,183 Less: current obligations under leases (678) (289) Long-term lease obligations $ 5,713 $ 894

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Schedule of benefit obligations, fair value of plan assets, and funded status	Benefit Obligations, Fair Value of Plan Assets and Funded Status Pension Benefits Other Postretirement and Postemployment Benefits December 31, December 31, (in millions) 2020 2019 2020 2019 Benefit obligation at beginning of period $ 21,199 $ 19,809 $ 3,379 $ 3,225 Service cost — — 96 83 Interest cost 700 833 120 137 Actuarial loss 2,051 1,678 247 226 Benefits paid, including lump sums and annuities (1,233) (1,107) (356) (315) Participant contributions — — 20 23 Special termination benefits — — 1,260 — Settlements (91) (14) — — Benefit obligation at end of period (1) $ 22,626 $ 21,199 $ 4,766 $ 3,379 Fair value of plan assets at beginning of period $ 15,845 $ 13,459 $ 607 $ 637 Actual gain on plan assets 1,973 2,485 76 134 Employer contributions 47 1,022 189 159 Participant contributions — — 20 23 Benefits paid, including lump sums and annuities (1,233) (1,107) (396) (346) Settlements (91) (14) — — Fair value of plan assets at end of period $ 16,541 $ 15,845 $ 496 $ 607 Funded status at end of period $ (6,085) $ (5,354) $ (4,270) $ (2,772) (1) At the end of each year presented, our accumulated benefit obligations for our pension plans are equal to the benefit obligations shown above.
Schedule of amounts balance sheet position	Balance Sheet Position Pension Benefits Other Postretirement and Postemployment Benefits December 31, December 31, (in millions) 2020 2019 2020 2019 Current liabilities $ (10) $ (19) $ (143) $ (125) Noncurrent liabilities (6,075) (5,335) (4,127) (2,647) Total liabilities $ (6,085) $ (5,354) $ (4,270) $ (2,772) Net actuarial loss $ (9,878) $ (8,765) $ (886) $ (715) Prior service credit — — 29 38 Total accumulated other comprehensive loss, pre-tax $ (9,878) $ (8,765) $ (857) $ (677)
Schedule of net periodic (benefit) cost	Net Periodic (Benefit) Cost Pension Benefits Other Postretirement and Postemployment Benefits Year Ended December 31, Year Ended December 31, (in millions) 2020 2019 2018 2020 2019 2018 Service cost $ — $ — $ — $ 96 $ 83 $ 85 Interest cost 700 833 781 120 137 126 Expected return on plan assets (1,373) (1,186) (1,318) (44) (47) (67) Amortization of prior service credit — — — (9) (9) (24) Recognized net actuarial loss 300 291 267 44 37 36 Settlements 38 5 4 — — — Special termination benefits — — — 1,260 — — Curtailment — — — — — (53) Net periodic (benefit) cost $ (335) $ (57) $ (266) $ 1,467 $ 201 $ 103
Schedule of assumptions used to determine benefit obligations and net periodic costs	We used the following actuarial assumptions to determine our benefit obligations and our net periodic benefit cost for the periods presented: December 31, Benefit Obligations (1) 2020 2019 Weighted average discount rate 2.62 % 3.40 % Year Ended December 31, Net Periodic (Benefit) Cost (1) 2020 2019 2018 Weighted average discount rate - pension benefit 3.40 % 4.33 % 3.69 % Weighted average discount rate - other postretirement benefit 3.47 % 4.32 % 3.69 % Weighted average discount rate - other postemployment benefit 3.34 % 4.32 % 3.65 % Weighted average expected long-term rate of return on plan assets 8.97 % 8.97 % 8.97 % Assumed healthcare cost trend rate for the next year (2) 6.25 % 6.50 % 6.75 % (1) Future employee compensation levels do not impact our frozen defined benefit pension plans or other postretirement plans and impact only a small portion of our other postemployment obligation. (2) Healthcare cost trend rate is assumed to decline gradually to 5.00% by 2026 and remain unchanged thereafter.
Schedule of expected future benefit payments	The following table summarizes the benefit payments that are expected to be paid in the years ending December 31: Expected future benefit payments (in millions) Pension Benefits Other Postretirement and Postemployment Benefits 2021 $ 1,280 $ 340 2022 1,270 370 2023 1,270 410 2024 1,270 430 2025 1,270 430 2026-2030 6,210 2,110
Schedule of benefit plan assets measured at fair value on recurring basis	The following table shows our benefit plan assets by asset class. Benefit plan assets measured at fair value on a recurring basis December 31, 2020 December 31, 2019 Valuation Technique (in millions) Level 1 Level 2 Total Level 1 Level 2 Total Equities and equity-related instruments $ 1,061 $ 59 $ 1,120 $ 840 $ 49 $ 889 (a) Delta common stock 507 — 507 737 — 737 (a) Cash equivalents 305 3,359 3,664 327 952 1,279 (a) Fixed income and fixed income-related instruments — 882 882 97 3,472 3,569 (a)(b) Benefit plan assets $ 1,873 $ 4,300 $ 6,173 $ 2,001 $ 4,473 $ 6,474 Investments measured at net asset value ("NAV") (1) 10,427 9,854 Total benefit plan assets $ 16,600 $ 16,328 (1) Investments that were measured at NAV per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy.
Schedule of benefit plan investments assets measured at NAV	The following table summarizes investments measured at fair value based on NAV per share as a practical expedient: Benefit plan investment assets measured at NAV December 31, 2020 December 31, 2019 (in millions) Fair Value Redemption Frequency Redemption Notice Period Fair Value Redemption Frequency Redemption Notice Period Hedge funds and hedge fund-related strategies (4) $ 5,474 (3) 2-180 Days $ 5,588 (3) 2-180 Days Commingled funds, private equity and private equity-related instruments (4) 2,136 (3) 3-30 Days 1,834 (3) 2-30 Days Fixed income and fixed income-related instruments (4) 1,118 (3) 15-90 Days 958 (3) 15-90 Days Real assets (4) 671 (2) N/A 758 (2) N/A Other 1,028 (1) 2-90 Days 716 (1) 2-90 Days Total investments measured at NAV $ 10,427 $ 9,854 (1) Weekly, semi-monthly, monthly (2) Semi-annually and annually (3) Various. Includes funds with weekly, semi-monthly, monthly, quarterly and custom redemption frequencies as well as funds with a redemption window following the anniversary of the initial investment. (4) Unfunded commitments were $916 million for commingled funds, private equity and private equity-related instruments, $264 million for fixed income and fixed income-related instruments and $181 million for real assets at December 31, 2020.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Schedule of aircraft purchase commitments	Our future aircraft purchase commitments totaled approximately $13.9 billion at December 31, 2020: Aircraft purchase commitments (in millions) Total 2021 $ 1,330 2022 2,470 2023 2,310 2024 2,960 2025 2,740 Thereafter 2,070 Total $ 13,880 Our future aircraft purchase commitments included the following aircraft at December 31, 2020: Aircraft purchase commitments by fleet type Fleet Type Purchase Commitments A220-100 7 A220-300 45 A321-200 22 A321-200neo 100 A330-900neo (1) 29 A350-900 20 CRJ-900 1 Total 224 (1) Includes one A330-900neo lease commitment in 2021 incremental to our order book with Airbus.
Schedule of contract carrier minimum obligations	Accordingly, our actual payments under these agreements could differ materially from the minimum fixed obligations set forth in the table below. Contract carrier minimum obligations (in millions) Amount (1) 2021 $ 1,413 2022 1,372 2023 1,240 2024 1,209 2025 837 Thereafter 1,654 Total $ 7,725 (1) These amounts exclude contract carrier payments accounted for as operating leases of aircraft, which are described in Note 9, "Leases."
Schedule of domestic airline employees represented by collective bargaining agreements by group	The following table shows our domestic airline employee groups that are represented by unions. Domestic airline employees represented by collective bargaining agreements by group Employee Group Approximate Number of Active Employees Represented Union Date on which Collective Bargaining Agreement Becomes Amendable Delta Pilots 12,940 ALPA December 31, 2019 Delta Flight Superintendents (Dispatchers) 350 PAFCA November 1, 2024 Endeavor Air Pilots 1,900 ALPA January 1, 2024 Endeavor Air Flight Attendants 1,480 AFA March 31, 2025

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of components of income tax benefit (provision)	Our income tax provision consisted of the following: Components of income tax benefit (provision) Year Ended December 31, (in millions) 2020 2019 2018 Current tax benefit (provision): Federal $ 94 $ 94 $ 187 State and local 3 (39) (26) International (5) (13) (13) Deferred tax benefit (provision): Federal 2,766 (1,343) (1,226) State and local 344 (130) (138) Income tax benefit (provision) $ 3,202 $ (1,431) $ (1,216)
Schedule of effective income tax rate reconciliation	The following table presents the principal reasons for the difference between the effective tax rate and the U.S. federal statutory income tax rate: Reconciliation of statutory federal income tax rate to the effective income tax rate Year Ended December 31, 2020 2019 2018 U.S. federal statutory income tax rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 1.9 2.3 2.5 Valuation allowance (2.6) 0.7 — Other 0.2 (0.9) 0.1 Effective income tax rate 20.5 % 23.1 % 23.6 %
Schedule of significant components of deferred income tax assets and liabilities	The following table shows significant components of our deferred tax assets and liabilities: Significant components of deferred income tax assets and liabilities December 31, (in millions) 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 1,495 $ 560 Capital loss carryforward 483 — Pension, postretirement and other benefits 2,956 2,241 Deferred revenue 1,797 1,667 Lease liabilities 2,185 1,510 Other 611 380 Valuation allowance (460) (58) Total deferred tax assets $ 9,067 $ 6,300 Deferred tax liabilities: Depreciation $ 4,507 $ 5,190 Operating lease assets 1,324 1,298 Intangible assets 1,076 1,049 Other 172 99 Total deferred tax liabilities $ 7,079 $ 7,636 Net deferred tax assets (liabilities) (1) $ 1,988 $ (1,336) (1) At December 31, 2020, the net deferred tax assets of $2.0 billion are recorded in deferred income taxes, net within noncurrent assets. At December 31, 2019, the net deferred tax liabilities of $1.3 billion included $120 million of net state deferred tax assets, which are recorded in deferred income taxes, net within noncurrent assets, and $1.5 billion of net federal deferred tax liabilities, which are recorded in deferred income taxes, net within noncurrent liabilities.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of components of accumulated other comprehensive loss	The following table shows the components of accumulated other comprehensive loss: Components of accumulated other comprehensive loss (in millions) Pension and Other Benefits Liabilities (2) Other (3) Available-for-Sale Investment s (4) Total Balance at January 1, 2018 (net of tax effect of $1,400) $ (7,812) $ 85 $ 106 $ (7,621) Changes in value (net of tax effect of $88) (294) 7 — (287) Reclassifications into retained earnings (net of tax effect of $61) — — (106) (106) Reclassifications into earnings (net of tax effect of $57) (1) 181 8 — 189 Balance at December 31, 2018 (net of tax effect of $1,492) (7,925) 100 — (7,825) Changes in value (net of tax effect of $133) (422) 7 — (415) Reclassifications into earnings (net of tax effect of $76) (1) 252 (1) — 251 Balance at December 31, 2019 (net of tax effect $1,549) (8,095) 106 — (7,989) Changes in value (net of tax effect of $384) (1,269) 17 — (1,252) Reclassifications into earnings (net of tax effect of $169) (1) 286 (83) — 203 Balance at December 31, 2020 (net of tax effect of $1,764) $ (9,078) $ 40 $ — $ (9,038) (1) Amounts reclassified from AOCI for pension and other benefits liabilities are recorded in miscellaneous, net in non-operating expense in the income statement. (2) Includes approximately $750 million of deferred income tax expense primarily related to pension and other benefit obligations that will not be recognized in net income until these obligations are fully extinguished. We consider all income sources, including other comprehensive income, in determining the amount of tax benefit allocated to results from operations. (3) In the June 2020 quarter, all remaining foreign currency hedges expired, and we recognized an $83 million tax benefit which was released from AOCI. (4) The 2018 reclassification into retained earnings related to our investments in GOL, China Eastern and other previously designated available-for-sale investments, and the related conversion to accounting for changes in fair value of these investments from AOCI to the income statement.

Segments (Tables)

Segments (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Schedule of financial information by segment	Segment results are prepared based on our internal accounting methods described below, with reconciliations to consolidated amounts in accordance with GAAP. Our segments are not designed to measure operating income or loss directly related to the products and services included in each segment on a stand-alone basis. Financial information by segment (in millions) Airline Refinery Intersegment Sales/Other Consolidated Year Ended December 31, 2020 Operating revenue: $ 15,945 $ 3,143 $ 17,095 Sales to airline segment $ (214) (1) Exchanged products (1,472) (2) Sales of refined products (307) (3) Operating loss (4) (12,253) (216) (12,469) Interest expense, net 928 1 929 Depreciation and amortization 2,312 99 (99) (4) 2,312 Restructuring charges 8,219 — 8,219 Total assets, end of period 70,548 1,448 71,996 Capital expenditures 1,879 20 1,899 Year Ended December 31, 2019 Operating revenue: $ 46,910 $ 5,558 $ 47,007 Sales to airline segment $ (1,103) (1) Exchanged products (3,963) (2) Sales of refined products (395) (3) Operating income (4) 6,542 76 6,618 Interest expense (income), net 327 (26) 301 Depreciation and amortization 2,581 99 (99) (4) 2,581 Total assets, end of period 62,793 1,739 64,532 Capital expenditures 4,880 56 4,936 Year Ended December 31, 2018 Operating revenue: $ 43,890 $ 5,458 $ 44,438 Sales to airline segment $ (962) (1) Exchanged products (3,596) (2) Sales of refined products (352) (3) Operating income (4) 5,206 58 5,264 Interest expense (income), net 334 (23) 311 Depreciation and amortization 2,329 67 (67) (4) 2,329 Total assets, end of period 58,561 1,705 60,266 Capital expenditures 5,005 163 5,168 (1) Represents transfers, valued on a market price basis, from the refinery to the airline segment for use in airline operations. We determine market price by reference to the market index for the primary delivery location, which is New York Harbor, for jet fuel from the refinery. (2) Represents value of products delivered under our exchange agreements, as discussed above, determined on a market price basis. (3) These sales were at or near cost; accordingly, the margin on these sales is de minimis. (4) Refinery segment operating results, including depreciation and amortization, are included within aircraft fuel and related taxes in our income statement.

(Loss)_Earnings Per Share (Tabl

(Loss)/Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted (loss)/earnings per share	The following table shows our computation of basic and diluted (loss)/earnings per share: Basic and diluted (loss)/earnings per share Year Ended December 31, (in millions, except per share data) 2020 2019 2018 Net (loss)/income $ (12,385) $ 4,767 $ 3,935 Basic weighted average shares outstanding 636 651 691 Dilutive effect of share-based awards — 2 3 Diluted weighted average shares outstanding 636 653 694 Basic (loss)/earnings per share $ (19.49) $ 7.32 $ 5.69 Diluted (loss)/earnings per share $ (19.49) $ 7.30 $ 5.67

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Summary of Significant Accounting Policies [Line Items]
Property and equipment, net	$ 26,529,000,000	$ 31,310,000,000
Depreciation and amortization expense related to property and equipment	2,312,000,000	2,581,000,000	$ 2,329,000,000
Amortization of capitalized software	304,000,000	239,000,000	205,000,000
Net book value of capitalized software	1,000,000,000	1,100,000,000
Fuel card obligation	1,100,000,000	736,000,000
Advertising expense	119,000,000	$ 288,000,000	$ 267,000,000
Fuel Card Obligation
Summary of Significant Accounting Policies [Line Items]
Purchasing card maximum limit	$ 1,100,000,000
Minimum
Summary of Significant Accounting Policies [Line Items]
Estimated residual value (percent)	5.00%
Maximum
Summary of Significant Accounting Policies [Line Items]
Estimated residual value (percent)	10.00%
Software and software development costs | Minimum
Summary of Significant Accounting Policies [Line Items]
Estimated useful life	3 years
Software and software development costs | Maximum
Summary of Significant Accounting Policies [Line Items]
Estimated useful life	10 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Property and Equipment, net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Less: accumulated depreciation and amortization	$ (17,511)	$ (17,027)
Total property and equipment, net	26,529	31,310
Flight equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 31,572	36,713
Flight equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years
Flight equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	34 years
Ground property and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 6,387	5,721
Ground property and equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Ground property and equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years
Information technology-related assets
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 3,403	3,276
Information technology-related assets | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Information technology-related assets | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Flight and ground equipment under capital lease
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,795	1,608
Less: accumulated depreciation and amortization	(793)	(546)
Advance payments for equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 883	$ 1,019

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Cash, Cash Equivalents, and Restricted Cash Reconciliation (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 8,307	$ 2,882	$ 1,565
Restricted cash included in prepaid expenses and other	192	212	47
Noncurrent Assets:
Cash restricted for airport construction	1,556	636	1,136
Total cash, cash equivalents and restricted cash	$ 10,055	$ 3,730	$ 2,748	$ 1,853

Impact of the COVID-19 Pandem_3

Impact of the COVID-19 Pandemic - Narrative (Details) employee in Thousands, $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended	9 Months Ended	10 Months Ended	12 Months Ended
	Jan. 31, 2021USD ($)	Mar. 31, 2021USD ($)	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)aircraftemployee	Dec. 31, 2020USD ($)aircraftemployee	Dec. 31, 2020USD ($)aircraftemployee	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2020employee
Impact Of Global Pandemic [Line Items]
Year-over-year decrease in system capacity (percent)					60.00%	50.00%
Number of aircraft retired | aircraft						227
Number of aircraft temporarily parked | aircraft				125	125	125
Number of aircraft removed from active service | aircraft						350
Number of employees volunteering for leave | employee						50
Salary reduction for CEO (percent)				100.00%
Salary reduction for company officers (percent)				50.00%
Work hours reduction for management and most front-line employee work groups (percent)				25.00%
Cash, cash equivalents, short-term investments, and amounts available under revolving credit facilities				$ 16,700	$ 16,700	$ 16,700
Financing transactions aggregate principal						25,900
Proceeds from payroll support program, CARES Act						5,600
Reduction in planned capital expenditures for the year						2,800
Capital expenditures						1,899	$ 4,936	$ 5,168
Subsequent event
Impact Of Global Pandemic [Line Items]
Proceeds from payroll support program	$ 1,400
Retired aircraft
Impact Of Global Pandemic [Line Items]
Cumulative net book value of retired aircraft				$ 500	$ 500	$ 500
Minimum
Impact Of Global Pandemic [Line Items]
Voluntary unpaid leave duration						30 days
Maximum
Impact Of Global Pandemic [Line Items]
Voluntary unpaid leave duration						12 months
Voluntary early retirement and separation programs
Impact Of Global Pandemic [Line Items]
Number of employees participating | employee				18	18	18			18
Forecast
Impact Of Global Pandemic [Line Items]
Proceeds from payroll support program		$ 1,500	$ 2,900
Forecast | Minimum
Impact Of Global Pandemic [Line Items]
Year-over-year decrease in system capacity (percent)			30.00%
Forecast | Maximum
Impact Of Global Pandemic [Line Items]
Year-over-year decrease in system capacity (percent)			40.00%
International
Impact Of Global Pandemic [Line Items]
Year-over-year decrease in system capacity (percent)					75.00%	65.00%
Domestic
Impact Of Global Pandemic [Line Items]
Year-over-year decrease in system capacity (percent)					50.00%	45.00%

Impact of the COVID-19 Pandem_4

Impact of the COVID-19 Pandemic - Restructuring Charges by Category (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Total Restructuring Charges	$ 8,219	$ 0	$ 0
Fleet Retirements
Restructuring Cost and Reserve [Line Items]
Total Restructuring Charges	4,409
Voluntary Programs and Other Employee Benefit Charges
Restructuring Cost and Reserve [Line Items]
Total Restructuring Charges	3,409
Receivables and Other
Restructuring Cost and Reserve [Line Items]
Total Restructuring Charges	$ 401

Impact of the COVID-19 Pandem_5

Impact of the COVID-19 Pandemic - Fleet Retirements by Aircraft Type (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)aircraft
Aircraft retirement decisions
Number of aircraft | aircraft		383
Impairment-related charge		$ 4,409
777
Aircraft retirement decisions
Number of aircraft | aircraft		18
Impairment-related charge		$ 1,440
767-300ER
Aircraft retirement decisions
Number of aircraft | aircraft		56
Impairment-related charge		$ 1,084
717
Aircraft retirement decisions
Number of aircraft | aircraft		91
Impairment-related charge		$ 950
MD-90
Aircraft retirement decisions
Number of aircraft | aircraft		26
Impairment-related charge		$ 335
CRJ-200
Aircraft retirement decisions
Number of aircraft | aircraft		125
Impairment-related charge		$ 320
737-700
Aircraft retirement decisions
Number of aircraft | aircraft		10
Impairment-related charge		$ 223
A-320
Aircraft retirement decisions
Number of aircraft | aircraft		10
Impairment-related charge		$ 57
MD-88
Aircraft retirement decisions
Number of aircraft | aircraft		47
Impairment-related charge		$ 0
Accelerated depreciation	$ 22

Impact of the COVID-19 Pandem_6

Impact of the COVID-19 Pandemic - Government Support Programs (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Jan. 15, 2021	Jan. 31, 2021	Mar. 31, 2021	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2030	Mar. 31, 2030	Dec. 31, 2025	Mar. 31, 2025
Impact Of Global Pandemic [Line Items]
Relief received through payroll support program, CARES Act					$ 5,600
Grant payments received through payroll support program, CARES Act					4,000
Additional liquidity through deferred payment of employer portion of social security taxes					$ 200
Subsequent event
Impact Of Global Pandemic [Line Items]
Proceeds from payroll support program		$ 1,400
Installment received through payroll support program	$ 1,400
Grant received as percent of total received through payroll support program	70.00%
Unsecured loan as percent of total received through payroll support program	30.00%
Forecast
Impact Of Global Pandemic [Line Items]
Proceeds from payroll support program			$ 1,500	$ 2,900
Grant payments received through payroll support program				$ 2,000
Delta Common Stock Warrants 2020
Impact Of Global Pandemic [Line Items]
Number shares called by warrants (in shares)					6.7
Shares called by warrants as percentage of outstanding shares					1.00%
Warrant exercise price (USD per share)					$ 24.39
Warrants term (in years)					5 years
Delta Common Stock Warrants 2021 | Subsequent event
Impact Of Global Pandemic [Line Items]
Number shares called by warrants (in shares)	1
Delta Common Stock Warrants 2021 | Forecast
Impact Of Global Pandemic [Line Items]
Number shares called by warrants (in shares)			2.1	2.1
Shares called by warrants as percentage of outstanding shares			0.50%	0.50%
Warrant exercise price (USD per share)			$ 39.73	$ 39.73
Warrants term (in years)				5 years
Unsecured Debt | Unsecured CARES Act Payroll Support Program Loan
Impact Of Global Pandemic [Line Items]
Unsecured loan per agreement through payroll support program, CARES Act					$ 1,600
Debt instrument term					10 years
Unsecured Debt | Unsecured CARES Act Payroll Support Program Loan | Forecast
Impact Of Global Pandemic [Line Items]
Annual interest rate (percent)									1.00%
Unsecured Debt | Unsecured CARES Act Payroll Support Program Loan | SOFR | Forecast
Impact Of Global Pandemic [Line Items]
Margin on rate (percent)							2.00%
Unsecured Debt | Unsecured Payroll Support Program Loan | Subsequent event
Impact Of Global Pandemic [Line Items]
Unsecured loan per agreement through payroll support program	$ 400
Unsecured Debt | Unsecured Payroll Support Program Loan | Forecast
Impact Of Global Pandemic [Line Items]
Debt instrument term				10 years
Annual interest rate (percent)								1.00%
Unsecured loan per agreement through payroll support program			$ 830	$ 830
Unsecured Debt | Unsecured Payroll Support Program Loan | SOFR | Forecast
Impact Of Global Pandemic [Line Items]
Margin on rate (percent)						2.00%

Revenue Recognition - Passenger

Revenue Recognition - Passenger Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Operating revenue	$ 17,095	$ 47,007	$ 44,438
Passenger
Disaggregation of Revenue [Line Items]
Operating revenue	12,883	42,277	39,755
Ticket
Disaggregation of Revenue [Line Items]
Operating revenue	10,970	36,908	34,950
Loyalty travel awards
Disaggregation of Revenue [Line Items]
Operating revenue	935	2,900	2,651
Travel-related services
Disaggregation of Revenue [Line Items]
Operating revenue	$ 978	$ 2,469	$ 2,154

Revenue Recognition - Narrative

Revenue Recognition - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total value of refunds to customers		$ 3,100
Travel credits as a percentage of air traffic liability	65.00%	65.00%
Revenue recognized that was in prior year air traffic liability		$ 3,100	$ 3,800	$ 3,500
Marketing contracts initial terms, minimum (in years)		3 years
Marketing contracts initial terms, maximum (in years)		11 years
Cash sales of miles from marketing agreements		$ 2,800	4,200	3,500
Proceeds from issuance of debt		$ 22,790	$ 2,057	$ 3,745
Majority of new miles, redemption period (in years)		2 years
Secured Debt | SkyMiles program
Disaggregation of Revenue [Line Items]
Proceeds from issuance of debt	$ 9,000

Revenue Recognition - Loyalty P

Revenue Recognition - Loyalty Program Liability (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loyalty Program
Miles earned	$ 1,437	$ 3,156	$ 3,142
Travel miles redeemed	(935)	(2,900)	(2,651)
Non-travel miles redeemed	(48)	(169)	(171)
Loyalty program
Loyalty Program
Deferred revenue (current and noncurrent), beginning	6,728	6,641	6,321
Deferred revenue (current and noncurrent), ending	$ 7,182	$ 6,728	$ 6,641

Revenue Recognition - Revenue b

Revenue Recognition - Revenue by Geographic Region (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Operating revenue	$ 17,095	$ 47,007	$ 44,438
Domestic
Disaggregation of Revenue [Line Items]
Operating revenue	13,339	33,382	31,309
Atlantic
Disaggregation of Revenue [Line Items]
Operating revenue	1,649	7,308	7,012
Latin America
Disaggregation of Revenue [Line Items]
Operating revenue	1,321	3,326	3,157
Pacific
Disaggregation of Revenue [Line Items]
Operating revenue	786	2,991	2,960
Passenger
Disaggregation of Revenue [Line Items]
Operating revenue	12,883	42,277	39,755
Passenger | Domestic
Disaggregation of Revenue [Line Items]
Operating revenue	10,041	30,465	28,235
Passenger | Atlantic
Disaggregation of Revenue [Line Items]
Operating revenue	1,171	6,326	6,135
Passenger | Latin America
Disaggregation of Revenue [Line Items]
Operating revenue	1,113	2,985	2,864
Passenger | Pacific
Disaggregation of Revenue [Line Items]
Operating revenue	$ 558	$ 2,501	$ 2,521

Revenue Recognition - Other Rev

Revenue Recognition - Other Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Operating revenue	$ 17,095	$ 47,007	$ 44,438
Other
Disaggregation of Revenue [Line Items]
Operating revenue	3,604	3,977	3,818
Ancillary businesses and refinery
Disaggregation of Revenue [Line Items]
Operating revenue	1,798	1,297	1,801
Loyalty program
Disaggregation of Revenue [Line Items]
Operating revenue	1,458	1,962	1,459
Miscellaneous
Disaggregation of Revenue [Line Items]
Operating revenue	$ 348	$ 718	$ 558

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Measurements on a Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Long-term investments	$ 1,417	$ 1,099
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	5,755	586
Restricted cash equivalents	1,747	847
Long-term investments	1,417	1,099
Recurring | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Short-term investments	5,789
Recurring | Fuel hedge contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Hedge derivatives, net	(9)	1
Recurring | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Hedge derivatives, net	23	61
Recurring | Foreign currency exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Hedge derivatives, net	(13)	6
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	5,755	586
Restricted cash equivalents	1,747	847
Long-term investments	948	881
Recurring | Level 1 | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Short-term investments	3,919
Recurring | Level 1 | Fuel hedge contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Hedge derivatives, net	0	(1)
Recurring | Level 1 | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Hedge derivatives, net	0	0
Recurring | Level 1 | Foreign currency exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Hedge derivatives, net	0	0
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0	0
Restricted cash equivalents	0	0
Long-term investments	38	33
Recurring | Level 2 | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Short-term investments	1,870
Recurring | Level 2 | Fuel hedge contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Hedge derivatives, net	(9)	2
Recurring | Level 2 | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Hedge derivatives, net	23	61
Recurring | Level 2 | Foreign currency exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Hedge derivatives, net	(13)	6
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0	0
Restricted cash equivalents	0	0
Long-term investments	431	185
Recurring | Level 3 | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Short-term investments	0
Recurring | Level 3 | Fuel hedge contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Hedge derivatives, net	0	0
Recurring | Level 3 | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Hedge derivatives, net	0	0
Recurring | Level 3 | Foreign currency exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Hedge derivatives, net	$ 0	$ 0

Investments - Narrative (Detail

Investments - Narrative (Details)	1 Months Ended		3 Months Ended			12 Months Ended
	May 31, 2020USD ($)aircraft	Jan. 31, 2020USD ($)aircraftjoint_venture_party$ / shares	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)aircraft	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2015USD ($)
Schedule of Equity Method Investments [Line Items]
Short-term investments							$ 5,789,000,000	$ 0
Short-term investments expected to mature in one year or less							4,900,000,000
Restructuring charges							8,219,000,000	0	$ 0
Impairments and equity method losses							2,432,000,000	62,000,000	60,000,000
Long-term investments							1,417,000,000	1,099,000,000
Net gain (loss) on investments							(105,000,000)	$ 119,000,000	$ 38,000,000
Number of parties in joint venture | joint_venture_party		3
Receivables from investees and other airlines
Schedule of Equity Method Investments [Line Items]
Reserve against outstanding receivables from Virgin Atlantic, Virgin Australia, LATAM, Grupo Aeromexico, and others							$ 100,000,000
LATAM
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)		20.00%		20.00%
Acquisition of strategic investments		$ 1,900,000,000
Per share price in tender offer (USD per share) | $ / shares		$ 16
Total consideration for investment					$ 2,300,000,000
Carrying value of equity investment					1,100,000,000
Impairments and equity method losses				$ 1,100,000,000
Grupo Aeromexico
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)			51.00%	51.00%
Impairments and equity method losses				$ 770,000,000
Voting interest limit per bylaws (percent)			49.00%
Virgin Atlantic
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)							49.00%	49.00%
Carrying value of equity investment			$ 0				$ 0	$ 375,000,000
Impairments and equity method losses							$ 510,000,000
Unifi Aviation
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)							49.00%	49.00%
Carrying value of equity investment							$ 154,000,000	$ 142,000,000
Alliance related
Schedule of Equity Method Investments [Line Items]
Consideration allocated to indefinite-lived intangible asset							1,200,000,000
Indefinite-lived intangibles							1,863,000,000	$ 1,005,000,000
Alliance related | LATAM
Schedule of Equity Method Investments [Line Items]
Consideration allocated to indefinite-lived intangible asset					1,200,000,000
Indefinite-lived intangibles							$ 1,200,000,000
LATAM
Schedule of Equity Method Investments [Line Items]
Planned investment to support establishment of strategic alliance		$ 350,000,000
Restructuring charges	$ 62,000,000			$ 62,000,000
LATAM | Forecast
Schedule of Equity Method Investments [Line Items]
Payments to support establishment of strategic alliance						$ 75,000,000
LATAM | A350
Schedule of Equity Method Investments [Line Items]
Number of aircraft agreed to acquire | aircraft		4
Number of purchase commitments assumed | aircraft		10					10
Number of aircraft in terminated purchase agreement | aircraft	4
LATAM and Grupo Aeromexico
Schedule of Equity Method Investments [Line Items]
Note payable							$ 165,000,000
Receivable							165,000,000
GOL | Loan receivable
Schedule of Equity Method Investments [Line Items]
Loan issued			$ 250,000,000
Loan receivable							93,000,000
Wheels Up
Schedule of Equity Method Investments [Line Items]
Gain on transaction to combine subsidiary with Wheels Up					$ 240,000,000
Virgin Atlantic
Schedule of Equity Method Investments [Line Items]
Receivable							$ 115,000,000
LATAM
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)							20.00%
Long-term investments							$ 0
Grupo Aeromexico
Schedule of Equity Method Investments [Line Items]
Long-term investments							$ 0
Wheels Up
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)							24.00%
Related agreements for Virgin Atlantic recapitalization process
Schedule of Equity Method Investments [Line Items]
Note payable							$ 115,000,000
Term loan facility | Financial Guarantee | GOL
Schedule of Equity Method Investments [Line Items]
Guarantee borrowings on third party debt										$ 300,000,000
Guarantee borrowings on third party debt, term (in years)										5 years

Investments - Fair Value Invest

Investments - Fair Value Investments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value Investments
Carrying value	$ 1,417	$ 1,099
Hanjin-KAL
Fair Value Investments
Ownership interest (percent)	13.00%	10.00%
Carrying value	$ 512	$ 205
Air France-KLM
Fair Value Investments
Ownership interest (percent)	9.00%	9.00%
Carrying value	$ 235	$ 418
China Eastern
Fair Value Investments
Ownership interest (percent)	3.00%	3.00%
Carrying value	$ 201	$ 258
Other Investments
Fair Value Investments
Carrying value	$ 469	$ 218

Investments - Equity Method Inv

Investments - Equity Method Investments (Details) - USD ($)	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Virgin Atlantic
Equity Method Investments
Ownership interest (percent)	49.00%		49.00%
Carrying value	$ 0	$ 0	$ 375,000,000
Unifi Aviation
Equity Method Investments
Ownership interest (percent)	49.00%		49.00%
Carrying value	$ 154,000,000		$ 142,000,000

Derivatives and Risk Manageme_3

Derivatives and Risk Management - Narrative (Details) ₩ in Millions	1 Months Ended		3 Months Ended	12 Months Ended
	Jan. 31, 2021USD ($)	Nov. 30, 2019KRW (₩)	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2020KRW (₩)	Dec. 31, 2019USD ($)	Dec. 31, 2019KRW (₩)
Derivative [Line Items]
Cash generated from unwinding of contracts			$ 100,000,000
Held margin on hedge contract				$ 0
Posted margin on hedge contract				0		$ 34,000,000
Subsequent event
Derivative [Line Items]
Cash generated from unwinding of contracts	$ 20,000,000
Not designated as hedges | Foreign exchange contract - won based
Derivative [Line Items]
Derivative, term of contract		3 years 6 months
Notional value | ₩		₩ 177,000			₩ 177,045		₩ 177,045
Unrealized loss on swap				$ 10,000,000

Derivatives and Risk Manageme_4

Derivatives and Risk Management - Hedge Position (Details) € in Millions, ₩ in Millions, gal in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020KRW (₩)gal	Dec. 31, 2019KRW (₩)gal	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2019EUR (€)	Nov. 30, 2019KRW (₩)
Derivatives, Fair Value [Line Items]
Total derivative contracts, net			$ 1	$ 68
Prepaid Expenses and Other
Derivatives, Fair Value [Line Items]
Total derivative contracts, assets			3	38
Other Noncurrent Assets
Derivatives, Fair Value [Line Items]
Total derivative contracts, assets			20	53
Other Accrued Liabilities
Derivatives, Fair Value [Line Items]
Total derivative contracts, liabilities			(9)	(19)
Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Total derivative contracts, liabilities			(13)	(4)
Foreign exchange contract - euro based | Not designated as hedges
Derivatives, Fair Value [Line Items]
Volume | €					€ 397
Total derivative contracts, net				9
Foreign exchange contract - euro based | Not designated as hedges | Prepaid Expenses and Other
Derivatives, Fair Value [Line Items]
Total derivative contracts, assets				9
Foreign exchange contract - euro based | Not designated as hedges | Other Noncurrent Assets
Derivatives, Fair Value [Line Items]
Total derivative contracts, assets				0
Foreign exchange contract - euro based | Not designated as hedges | Other Accrued Liabilities
Derivatives, Fair Value [Line Items]
Total derivative contracts, liabilities				0
Foreign exchange contract - euro based | Not designated as hedges | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Total derivative contracts, liabilities				0
Foreign exchange contract - won based | Not designated as hedges
Derivatives, Fair Value [Line Items]
Volume | ₩	₩ 177,045	₩ 177,045				₩ 177,000
Total derivative contracts, net			(13)	(3)
Foreign exchange contract - won based | Not designated as hedges | Prepaid Expenses and Other
Derivatives, Fair Value [Line Items]
Total derivative contracts, assets			0	1
Foreign exchange contract - won based | Not designated as hedges | Other Noncurrent Assets
Derivatives, Fair Value [Line Items]
Total derivative contracts, assets			0	0
Foreign exchange contract - won based | Not designated as hedges | Other Accrued Liabilities
Derivatives, Fair Value [Line Items]
Total derivative contracts, liabilities			0	0
Foreign exchange contract - won based | Not designated as hedges | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Total derivative contracts, liabilities			(13)	(4)
Fuel hedge contracts | Not designated as hedges
Derivatives, Fair Value [Line Items]
Volume, nonmonetary | gal	157	243
Total derivative contracts, net			(9)	1
Fuel hedge contracts | Not designated as hedges | Prepaid Expenses and Other
Derivatives, Fair Value [Line Items]
Total derivative contracts, assets			0	16
Fuel hedge contracts | Not designated as hedges | Other Noncurrent Assets
Derivatives, Fair Value [Line Items]
Total derivative contracts, assets			0	0
Fuel hedge contracts | Not designated as hedges | Other Accrued Liabilities
Derivatives, Fair Value [Line Items]
Total derivative contracts, liabilities			(9)	(15)
Fuel hedge contracts | Not designated as hedges | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Total derivative contracts, liabilities			0	0
Fair value hedge | Interest rate contracts | Designated as hedges
Derivatives, Fair Value [Line Items]
Volume			150	1,872
Total derivative contracts, net			23	61
Fair value hedge | Interest rate contracts | Designated as hedges | Prepaid Expenses and Other
Derivatives, Fair Value [Line Items]
Total derivative contracts, assets			3	12
Fair value hedge | Interest rate contracts | Designated as hedges | Other Noncurrent Assets
Derivatives, Fair Value [Line Items]
Total derivative contracts, assets			20	53
Fair value hedge | Interest rate contracts | Designated as hedges | Other Accrued Liabilities
Derivatives, Fair Value [Line Items]
Total derivative contracts, liabilities			0	(4)
Fair value hedge | Interest rate contracts | Designated as hedges | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Total derivative contracts, liabilities			$ 0	$ 0

Derivatives and Risk Manageme_5

Derivatives and Risk Management - Balance Sheet Location of Hedged Item (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Cumulative amount of adjustments remaining for which hedge accounting has been discontinued	$ 76
Current maturities of debt and finance leases
Derivative [Line Items]
Carrying amount of hedge instruments	21	$ (19)
Cumulative amount of fair value hedge adjustments	21	8
Debt and finance leases
Derivative [Line Items]
Carrying amount of hedge instruments	(72)	(1,783)
Cumulative amount of fair value hedge adjustments	$ 77	$ 53

Derivatives and Risk Manageme_6

Derivatives and Risk Management - Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Total derivative contracts, net	$ 1	$ 68
Prepaid Expenses and Other
Derivative [Line Items]
Net derivative contracts, assets	3	24
Other Noncurrent Assets
Derivative [Line Items]
Net derivative contracts, assets	20	53
Other Accrued Liabilities
Derivative [Line Items]
Net derivative contracts, liabilities	(9)	(5)
Other Noncurrent Liabilities
Derivative [Line Items]
Net derivative contracts, liabilities	$ (13)	$ (4)

Derivatives and Risk Manageme_7

Derivatives and Risk Management - Not Designated Hedge Gains (Losses) (Details) - Not designated as hedges - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives recognized	$ 54	$ (31)	$ 48
Foreign currency exchange contracts | Gain/(loss) on investments, net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives recognized	(31)	10	(4)
Fuel hedge contracts | Aircraft fuel and related taxes
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives recognized	$ 85	$ (41)	$ 52

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Valuation of Goodwill and Indefinite-Lived Intangible (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Indefinite-lived Intangible Assets
Goodwill	$ 9,753	$ 9,781
Goodwill and indefinite-lived intangibles	$ 15,671	14,841
Minimum
Indefinite-lived Intangible Assets
Fair Value Excess at 2020 Testing Date (greater than)	100.00%
International routes and slots
Indefinite-lived Intangible Assets
Indefinite-lived intangibles	$ 2,583	2,583
International routes and slots | Minimum
Indefinite-lived Intangible Assets
Fair Value Excess at 2020 Testing Date	10.00%
International routes and slots | Maximum
Indefinite-lived Intangible Assets
Fair Value Excess at 2020 Testing Date	30.00%
Airline alliances
Indefinite-lived Intangible Assets
Indefinite-lived intangibles	$ 1,863	1,005
Indefinite-lived intangible asset acquired	$ 1,200
Airline alliances | Minimum
Indefinite-lived Intangible Assets
Fair Value Excess at 2020 Testing Date	20.00%
Airline alliances | Maximum
Indefinite-lived Intangible Assets
Fair Value Excess at 2020 Testing Date (greater than)	100.00%
Delta tradename
Indefinite-lived Intangible Assets
Indefinite-lived intangibles	$ 850	850
Fair Value Excess at 2020 Testing Date (greater than)	100.00%
Domestic slots
Indefinite-lived Intangible Assets
Indefinite-lived intangibles	$ 622	$ 622
Domestic slots | Minimum
Indefinite-lived Intangible Assets
Fair Value Excess at 2020 Testing Date	60.00%
Domestic slots | Maximum
Indefinite-lived Intangible Assets
Fair Value Excess at 2020 Testing Date (greater than)	100.00%

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Definite-Lived Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets
Gross carrying value	$ 976	$ 976
Accumulated amortization	(883)	(873)
Marketing agreements
Finite-Lived Intangible Assets
Gross carrying value	730	730
Accumulated amortization	(696)	(692)
Contracts
Finite-Lived Intangible Assets
Gross carrying value	193	193
Accumulated amortization	(134)	(128)
Other
Finite-Lived Intangible Assets
Gross carrying value	53	53
Accumulated amortization	$ (53)	$ (53)

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets
Amortization expense	$ 10	$ 11	$ 17
Estimated amortization expense in 2021	9
Estimated amortization expense in 2022	9
Estimated amortization expense in 2023	9
Estimated amortization expense in 2024	9
Estimated amortization expense in 2025	$ 9

Debt - Summary of Debt (Details

Debt - Summary of Debt (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total secured and unsecured debt	$ 28,214			$ 9,991
Unamortized (discount)/premium and debt issuance cost, net and other	(240)			115
Total debt	27,974			10,106
Less: current maturities	(1,443)			(2,054)
Total long-term debt	$ 26,531			8,052
Unsecured notes | Unsecured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 1, 2021
Maturity dates range, end	Dec. 31, 2029
Total secured and unsecured debt	$ 5,350			5,550
Unsecured notes | Unsecured Debt | Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	2.90%
Unsecured notes | Unsecured Debt | Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	7.38%
Unsecured CARES Act Payroll Support Program Loan | Unsecured Debt
Debt Instrument [Line Items]
Interest rate per annum (percent)	0.01%
Total secured and unsecured debt	$ 1,648			0
Maturity date	Dec. 31, 2030
SkyMiles Notes | Secured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 1, 2023
Maturity dates range, end	Dec. 31, 2028
Total secured and unsecured debt	$ 6,000			0
SkyMiles Notes | Secured Debt | Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	4.50%
SkyMiles Notes | Secured Debt | Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	4.75%
SkyMiles Term Loan | Secured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 1, 2023
Maturity dates range, end	Dec. 31, 2027
Interest rate per annum (percent)	4.75%
Total secured and unsecured debt	$ 3,000			0
2020 Senior Secured Notes | Secured Debt
Debt Instrument [Line Items]
Interest rate per annum (percent)	7.00%		7.00%
Total secured and unsecured debt	$ 3,500			0
Maturity date	Dec. 31, 2025
2020 Term Loan | Secured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 1, 2021
Maturity dates range, end	Dec. 31, 2023
Interest rate per annum (percent)	5.75%
Total secured and unsecured debt	$ 1,493			0
2018 Revolving Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 1, 2021
Maturity dates range, end	Dec. 31, 2023
Total secured and unsecured debt	$ 0			0
Financings secured by aircraft - Certificates | Secured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 1, 2021
Maturity dates range, end	Dec. 31, 2028
Total secured and unsecured debt	$ 2,633			1,669
Financings secured by aircraft - Certificates | Secured Debt | Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	2.00%
Financings secured by aircraft - Certificates | Secured Debt | Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	8.02%
Financings secured by aircraft - Notes | Secured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 1, 2021
Maturity dates range, end	Dec. 31, 2032
Total secured and unsecured debt	$ 1,284			1,193
Financings secured by aircraft - Notes | Secured Debt | Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	0.81%
Financings secured by aircraft - Notes | Secured Debt | Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	5.75%
NYTDC Special Facilities Revenue Bonds, Series 2020 | Bonds
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 1, 2026
Maturity dates range, end	Dec. 31, 2045
Total secured and unsecured debt	$ 1,511	$ 1,500		0
NYTDC Special Facilities Revenue Bonds, Series 2020 | Bonds | Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	4.00%
NYTDC Special Facilities Revenue Bonds, Series 2020 | Bonds | Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	5.00%
NYTDC Special Facilities Revenue Bonds, Series 2018 | Bonds
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 1, 2022
Maturity dates range, end	Dec. 31, 2036
Total secured and unsecured debt	$ 1,383			1,383
NYTDC Special Facilities Revenue Bonds, Series 2018 | Bonds | Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	4.00%
NYTDC Special Facilities Revenue Bonds, Series 2018 | Bonds | Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	5.00%
Other financings | Secured and Unsecured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 1, 2021
Maturity dates range, end	Dec. 31, 2030
Total secured and unsecured debt	$ 412			196
Other financings | Secured and Unsecured Debt | Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	2.51%
Other financings | Secured and Unsecured Debt | Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	8.75%
Other revolving credit facilities | Revolving Credit Facility
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 1, 2021
Maturity dates range, end	Dec. 31, 2022
Total secured and unsecured debt	$ 0			$ 0

Debt - Narrative (Details)

Debt - Narrative (Details) shares in Millions	1 Months Ended		2 Months Ended	3 Months Ended				9 Months Ended	12 Months Ended
	Jan. 31, 2021USD ($)	Sep. 30, 2020USD ($)subsidiary	Mar. 31, 2021USD ($)shares	Mar. 31, 2021USD ($)shares	Dec. 31, 2020USD ($)shares	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)shares	Dec. 31, 2020USD ($)aircraftshares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Jan. 15, 2021USD ($)shares	Apr. 30, 2020USD ($)
Debt Instrument [Line Items]
Relative fair value basis					$ 29,800,000,000			$ 29,800,000,000	$ 29,800,000,000	$ 10,400,000,000
Government support warrant issuance									114,000,000
Proceeds from issuance of debt									22,790,000,000	2,057,000,000	$ 3,745,000,000
Aggregate principal amount					28,214,000,000			28,214,000,000	28,214,000,000	9,991,000,000
Outstanding letters of credit that reduce availability under revolvers					300,000,000			300,000,000	300,000,000
Outstanding letters of credit that do not affect availability of revolvers					$ 300,000,000			$ 300,000,000	300,000,000
Forecast
Debt Instrument [Line Items]
Proceeds from payroll support program			$ 1,500,000,000	$ 2,900,000,000
Subsequent event
Debt Instrument [Line Items]
Proceeds from payroll support program	$ 1,400,000,000
Additional Paid-in Capital
Debt Instrument [Line Items]
Government support warrant issuance									$ 114,000,000
Delta Common Stock Warrants 2020
Debt Instrument [Line Items]
Number shares called by warrants (in shares) | shares					6.7			6.7	6.7
Delta Common Stock Warrants 2021 | Forecast
Debt Instrument [Line Items]
Number shares called by warrants (in shares) | shares			2.1	2.1
Delta Common Stock Warrants 2021 | Subsequent event
Debt Instrument [Line Items]
Number shares called by warrants (in shares) | shares												1
Revolving Credit Facility
Debt Instrument [Line Items]
Proceeds from revolving credit facilities					$ 2,600,000,000			$ 2,600,000,000	$ 2,600,000,000
2020 Unsecured Notes | Unsecured Debt
Debt Instrument [Line Items]
Debt instrument face amount						$ 1,300,000,000
Interest rate per annum (percent)						7.375%
Unsecured CARES Act Payroll Support Program Loan | Unsecured Debt
Debt Instrument [Line Items]
Interest rate per annum (percent)					0.01%			0.01%	0.01%
Unsecured loan per agreement through payroll support program, CARES Act					$ 1,600,000,000			$ 1,600,000,000	$ 1,600,000,000
Relative fair value basis					1,500,000,000			$ 1,500,000,000	1,500,000,000
Debt instrument term								10 years
Aggregate principal amount					$ 1,648,000,000			$ 1,648,000,000	$ 1,648,000,000	0
Unsecured Payroll Support Program Loan | Unsecured Debt | Forecast
Debt Instrument [Line Items]
Unsecured loan per agreement through payroll support program			$ 830,000,000	$ 830,000,000
Debt instrument term				10 years
Unsecured Payroll Support Program Loan | Unsecured Debt | Subsequent event
Debt Instrument [Line Items]
Unsecured loan per agreement through payroll support program												$ 400,000,000
SkyMiles Notes due 2025 | Secured Debt
Debt Instrument [Line Items]
Debt instrument face amount		$ 2,500,000,000
Interest rate per annum (percent)		4.50%
SkyMiles Notes due 2028 | Secured Debt
Debt Instrument [Line Items]
Debt instrument face amount		$ 3,500,000,000
Interest rate per annum (percent)		4.75%
SkyMiles Term Loan | Secured Debt
Debt Instrument [Line Items]
Debt instrument face amount		$ 3,000,000,000
Interest rate per annum (percent)					4.75%			4.75%	4.75%
LIBOR minimum per annum (percent)		1.00%
Aggregate principal amount					$ 3,000,000,000			$ 3,000,000,000	$ 3,000,000,000	0
SkyMiles Term Loan | Secured Debt | LIBOR
Debt Instrument [Line Items]
Margin on rate (percent)		3.75%
SkyMiles debt | Secured Debt
Debt Instrument [Line Items]
Number of subsidiaries on debt guarantee | subsidiary		3
2020 Senior Secured Notes | Secured Debt
Debt Instrument [Line Items]
Debt instrument face amount						$ 3,500,000,000
Interest rate per annum (percent)					7.00%	7.00%		7.00%	7.00%
Aggregate principal amount					$ 3,500,000,000			$ 3,500,000,000	$ 3,500,000,000	0
2020 Term Loan | Secured Debt
Debt Instrument [Line Items]
Debt instrument face amount						$ 1,500,000,000
Interest rate per annum (percent)					5.75%			5.75%	5.75%
Required payments per year (percent)						1.00%
Aggregate principal amount					$ 1,493,000,000			$ 1,493,000,000	$ 1,493,000,000	0
2018 Revolving Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit subject to extended maturity						$ 1,300,000,000
Aggregate principal amount					0			0	0	0
2020 Secured Term Loan Facility | Secured Term Loan
Debt Instrument [Line Items]
Debt instrument face amount							$ 2,700,000,000						$ 3,000,000,000
Debt instrument term							364 days
Pass Through Certificates 2020-1 | Secured Debt
Debt Instrument [Line Items]
Debt instrument face amount					1,135,000,000			1,135,000,000	$ 1,135,000,000
Proceeds from issuance of debt						$ 135,000,000	$ 1,000,000,000
Number of aircraft to secure debt | aircraft									33
Pass Through Certificates 2019-1 Class B | Secured Debt
Debt Instrument [Line Items]
Interest rate per annum (percent)						8.00%
Proceeds from issuance of debt						$ 108,000,000
NYTDC Special Facilities Revenue Bonds, Series 2020 | Bonds
Debt Instrument [Line Items]
Aggregate principal amount		$ 1,500,000,000			1,511,000,000			1,511,000,000	$ 1,511,000,000	$ 0
Credit facilities and SkyMiles financing agreements
Debt Instrument [Line Items]
Minimum liquidity covenant					2,000,000,000			2,000,000,000	2,000,000,000
SkyMiles program
Debt Instrument [Line Items]
Aggregate limit on sale of pre-paid miles covenant					550,000,000			$ 550,000,000	$ 550,000,000
SkyMiles program | Secured Debt
Debt Instrument [Line Items]
Proceeds from issuance of debt					$ 9,000,000,000

Debt - 2020-1 EETC (Details)

Debt - 2020-1 EETC (Details) - Secured Debt	10 Months Ended
	Dec. 31, 2020USD ($)
Pass Through Certificates 2020-1
Debt Instrument [Line Items]
Total principal	$ 1,135,000,000
2020-1 Class AA Certificates
Debt Instrument [Line Items]
Total principal	$ 796,000,000
Fixed interest rate (percent)	2.00%
Issuance date	Mar. 1, 2020
Final maturity date	Jun. 30, 2028
2020-1 Class A Certificates
Debt Instrument [Line Items]
Total principal	$ 204,000,000
Fixed interest rate (percent)	2.50%
Issuance date	Mar. 1, 2020
Final maturity date	Jun. 30, 2028
2020-1 Class B Certificates
Debt Instrument [Line Items]
Total principal	$ 135,000,000
Fixed interest rate (percent)	8.00%
Issuance date	Apr. 1, 2020
Final maturity date	Jun. 30, 2027

Debt - Fair Value of Debt (Deta

Debt - Fair Value of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Net carrying amount	$ 27,974	$ 10,106
Fair value	$ 29,800	$ 10,400

Debt - Future Maturities (Detai

Debt - Future Maturities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Total Debt
2021	$ 1,480
2022	1,882
2023	4,016
2024	3,126
2025	5,157
Thereafter	12,553
Total	28,214	$ 9,991
Amortization of Debt (Discount)/Premium and Debt Issuance Cost, net and other
2021	(62)
2022	(63)
2023	(54)
2024	(46)
2025	(23)
Thereafter	8
Total	(240)	115
Total debt	$ 27,974	$ 10,106

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)aircraftairportleasetransaction
Lessee, Lease, Description [Line Items]
Leases that have not yet commenced | $	$ 734
Aircraft sale leaseback
Lessee, Lease, Description [Line Items]
Sale leaseback transactions | $	$ 2,800
Number of aircraft in sale-leaseback transactions	85
Number of sale-leaseback transactions that did not qualify as sale | transaction	74
Number of sale-leaseback transactions that qualified as sale | transaction	11
Aircraft sale leaseback | A321-200
Lessee, Lease, Description [Line Items]
Number of aircraft in sale-leaseback transactions	25
Aircraft sale leaseback | A220-100
Lessee, Lease, Description [Line Items]
Number of aircraft in sale-leaseback transactions	25
Aircraft sale leaseback | CRJ-900
Lessee, Lease, Description [Line Items]
Number of aircraft in sale-leaseback transactions	23
Aircraft sale leaseback | 737-900ER
Lessee, Lease, Description [Line Items]
Number of aircraft in sale-leaseback transactions	10
Aircraft sale leaseback | A330-900
Lessee, Lease, Description [Line Items]
Number of aircraft in sale-leaseback transactions	2
Minimum
Lessee, Lease, Description [Line Items]
Leases that have not yet commenced, term of contract	7 years
Maximum
Lessee, Lease, Description [Line Items]
Leases that have not yet commenced, term of contract	12 years
Aircraft
Lessee, Lease, Description [Line Items]
Number of leases | lease	353
Number of finance leases | lease	145
Number of operating leases | lease	208
Lease component of purchase agreements, number of aircraft	125
Aircraft | Minimum
Lessee, Lease, Description [Line Items]
Remaining term of finance leases	1 month
Remaining term of operating leases	1 month
Aircraft | Maximum
Lessee, Lease, Description [Line Items]
Remaining term of finance leases	15 years
Remaining term of operating leases	15 years
Airport Facilities
Lessee, Lease, Description [Line Items]
Number of airports with facility space under lease | airport	300
Airport Facilities | Minimum
Lessee, Lease, Description [Line Items]
Remaining term of operating leases	1 month
Airport Facilities | Maximum
Lessee, Lease, Description [Line Items]
Remaining term of operating leases	30 years
Other Ground Property and Equipment | Minimum
Lessee, Lease, Description [Line Items]
Remaining term of finance leases	1 month
Remaining term of operating leases	1 month
Other Ground Property and Equipment | Maximum
Lessee, Lease, Description [Line Items]
Remaining term of finance leases	9 years
Remaining term of operating leases	9 years

Leases - Lease Position (Detail

Leases - Lease Position (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Assets
Operating lease assets	$ 5,733	$ 5,627
Finance lease assets	1,002	1,062
Total lease assets	$ 6,735	$ 6,689
Finance lease asset, balance sheet	us-gaap:PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	us-gaap:PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization
Liabilities
Current operating lease liabilities	$ 678	$ 801
Current finance lease liabilities	289	233
Noncurrent operating lease liabilities	5,713	5,294
Noncurrent finance lease liabilities	894	821
Total lease liabilities	$ 7,574	$ 7,149
Operating leases, weighted-average remaining lease term	12 years	12 years
Finance leases, weighted-average remaining lease term	5 years	5 years
Operating leases, weighted-average discount rate	4.88%	3.73%
Finance leases, weighted-average discount rate	3.61%	3.46%
Finance lease liability, current, balance sheet	us-gaap:LongTermDebtAndCapitalLeaseObligationsCurrent	us-gaap:LongTermDebtAndCapitalLeaseObligationsCurrent
Finance lease liability, noncurrent, balance sheet	us-gaap:LongTermDebtAndCapitalLeaseObligations	us-gaap:LongTermDebtAndCapitalLeaseObligations

Leases - Lease Costs (Details)

Leases - Lease Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Finance lease cost, amortization of leased assets	$ 131	$ 110	$ 100
Finance lease cost, interest of lease liabilities	32	29	22
Operating lease cost	1,019	1,013	994
Short-term lease cost	264	500	458
Variable lease cost	1,406	1,456	1,427
Total lease cost	2,852	3,108	3,001
Regional carrier
Lessee, Lease, Description [Line Items]
Operating lease cost	187	174	150
Short-term lease cost			18
Variable lease cost	$ 50	$ 64	$ 48

Leases - Other Information (Det

Leases - Other Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating cash flows for operating leases	$ 1,053	$ 1,166	$ 1,271
Operating cash flows for finance leases	32	27	22
Financing cash flows for finance leases	$ 255	$ 192	$ 108

Leases - Undiscounted Cash Flow

Leases - Undiscounted Cash Flows (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Operating Leases
2021	$ 949
2022	848
2023	837
2024	770
2025	746
Thereafter	4,450
Total minimum lease payments	8,600
Less: amount of lease payments representing interest	(2,209)
Present value of future minimum lease payments	6,391
Less: current obligations under leases	(678)	$ (801)
Noncurrent operating lease liabilities	5,713	5,294
Finance Leases
2021	328
2022	238
2023	191
2024	266
2025	128
Thereafter	149
Total minimum lease payments	1,300
Less: amount of lease payments representing interest	(117)
Present value of future minimum lease payments	1,183
Less: current obligations under leases	(289)	(233)
Long-term lease obligations	$ 894	$ 821

Airport Redevelopment (Details)

Airport Redevelopment (Details) - USD ($) $ in Millions	12 Months Ended		48 Months Ended
	Dec. 31, 2020	Dec. 31, 2010	Dec. 31, 2020	Dec. 31, 2017
Financial Guarantee | Revolving Credit Facility
Agreements and Obligations [Line Items]
Aggregate commitments guaranteed	$ 800		$ 800
JFK IAT Member LLC
Agreements and Obligations [Line Items]
Lease agreement, term		33 years
Port Authority
Agreements and Obligations [Line Items]
Special project bonds face amount		$ 800
NYTDC
Agreements and Obligations [Line Items]
Special project bonds face amount	611
LAX Redevelopment Project
Agreements and Obligations [Line Items]
Total expected project costs	2,300		2,300
Expected net projects costs	500		500
Project costs reflected as investing cash flows			200
Amount spent on project costs	315
Project costs paid by credit facility	293
Project costs paid by company	22
LAX Redevelopment Project | City of Los Angeles
Agreements and Obligations [Line Items]
Total appropriation to date by city	1,800		1,800
Maximum reimbursement by city	1,800		1,800
LaGuardia Airport Redevelopment Project
Agreements and Obligations [Line Items]
Expected net projects costs	3,500		3,500
Amount spent on project costs	$ 600		$ 1,500
Port Authority contribution to redevelopment project				$ 481

Employee Benefit Plans - Benefi

Employee Benefit Plans - Benefit Obligations, Fair Value of Plan Assets and Funded Status (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Change in Benefit Obligation
Benefit obligation at beginning of period		$ 21,199	$ 19,809
Service cost		0	0	$ 0
Interest cost		700	833	781
Actuarial loss		2,051	1,678
Benefits paid, including lump sums and annuities		(1,233)	(1,107)
Participant contributions		0	0
Special termination benefits		0	0
Settlements		(91)	(14)
Benefit obligation at end of period		22,626	21,199	19,809
Change in Fair Value of Plan Assets
Fair value of plan assets at beginning of period		15,845	13,459
Actual gain on plan assets		1,973	2,485
Employer contributions		47	1,022
Participant contributions		0	0
Benefits paid, including lump sums and annuities		(1,233)	(1,107)
Settlements		(91)	(14)
Fair value of plan assets at end of period		16,541	15,845	13,459
Funded Status of Plan
Funded status at end of period		(6,085)	(5,354)
Other Postretirement and Postemployment Benefits
Change in Benefit Obligation
Benefit obligation at beginning of period		3,379	3,225
Service cost		96	83	85
Interest cost		120	137	126
Actuarial loss		247	226
Benefits paid, including lump sums and annuities		(356)	(315)
Participant contributions		20	23
Special termination benefits	$ 1,300	1,260	0
Settlements		0	0
Benefit obligation at end of period		4,766	3,379	3,225
Change in Fair Value of Plan Assets
Fair value of plan assets at beginning of period		607	637
Actual gain on plan assets		76	134
Employer contributions		189	159
Participant contributions		20	23
Benefits paid, including lump sums and annuities		(396)	(346)
Settlements		0	0
Fair value of plan assets at end of period		496	607	$ 637
Funded Status of Plan
Funded status at end of period		$ (4,270)	$ (2,772)

Employee Benefit Plans - Balanc

Employee Benefit Plans - Balance Sheet Position (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Pension and Other Postretirement Defined Benefit Plans, Liabilities
Noncurrent liabilities	$ (10,630)	$ (8,452)
Pension Benefits
Pension and Other Postretirement Defined Benefit Plans, Liabilities
Current liabilities	(10)	(19)
Noncurrent liabilities	(6,075)	(5,335)
Total liabilities	(6,085)	(5,354)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax
Net actuarial loss	(9,878)	(8,765)
Prior service credit	0	0
Total accumulated other comprehensive loss, pre-tax	(9,878)	(8,765)
Other Postretirement and Postemployment Benefits
Pension and Other Postretirement Defined Benefit Plans, Liabilities
Current liabilities	(143)	(125)
Noncurrent liabilities	(4,127)	(2,647)
Total liabilities	(4,270)	(2,772)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax
Net actuarial loss	(886)	(715)
Prior service credit	29	38
Total accumulated other comprehensive loss, pre-tax	$ (857)	$ (677)

Employee Benefit Plans - Net Pe

Employee Benefit Plans - Net Periodic (Benefit) Cost (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Defined Benefit Plan Disclosure
Service cost		$ 0	$ 0	$ 0
Interest cost		700	833	781
Expected return on plan assets		(1,373)	(1,186)	(1,318)
Amortization of prior service credit		0	0	0
Recognized net actuarial loss		300	291	267
Settlements		38	5	4
Special termination benefits		0	0	0
Curtailment		0	0	0
Net periodic (benefit) cost		(335)	(57)	(266)
Other Postretirement and Postemployment Benefits
Defined Benefit Plan Disclosure
Service cost		96	83	85
Interest cost		120	137	126
Expected return on plan assets		(44)	(47)	(67)
Amortization of prior service credit		(9)	(9)	(24)
Recognized net actuarial loss		44	37	36
Settlements		0	0	0
Special termination benefits	$ 1,300	1,260	0	0
Curtailment		0	0	(53)
Net periodic (benefit) cost		$ 1,467	$ 201	$ 103

Employee Benefit Plans - Assump

Employee Benefit Plans - Assumptions Used to Determine Benefit Obligation and Net Periodic Benefit Cost (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure
Weighted average discount rate (percent)	2.62%	3.40%
Weighted average expected long-term rate of return on plan assets (percent)	8.97%	8.97%	8.97%
Assumed healthcare cost trend rate for the next year (percent)	6.25%	6.50%	6.75%
Ultimate healthcare cost trend rate (percent)	5.00%
Pension Benefits
Defined Benefit Plan Disclosure
Weighted average discount rate (percent)	3.40%	4.33%	3.69%
Other Postretirement Benefits
Defined Benefit Plan Disclosure
Weighted average discount rate (percent)	3.47%	4.32%	3.69%
Other Postemployment Benefits
Defined Benefit Plan Disclosure
Weighted average discount rate (percent)	3.34%	4.32%	3.65%

Employee Benefit Plans - Expect

Employee Benefit Plans - Expected Benefit Payments (Details) $ in Millions	Dec. 31, 2020USD ($)
Pension Benefits
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity
2021	$ 1,280
2022	1,270
2023	1,270
2024	1,270
2025	1,270
2026-2030	6,210
Other Postretirement and Postemployment Benefits
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity
2021	340
2022	370
2023	410
2024	430
2025	430
2026-2030	$ 2,110

Employee Benefit Plans - Bene_2

Employee Benefit Plans - Benefit Plan Assets Measured at Fair Value on Recurring Basis (Details) - Recurring - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Benefit plan assets by asset class
Benefit plan assets	$ 16,600	$ 16,328
Level 1 and Level 2
Benefit plan assets by asset class
Benefit plan assets	6,173	6,474
Level 1 and Level 2 | Equities and equity-related instruments
Benefit plan assets by asset class
Benefit plan assets	1,120	889
Level 1 and Level 2 | Delta common stock
Benefit plan assets by asset class
Benefit plan assets	507	737
Level 1 and Level 2 | Cash equivalents
Benefit plan assets by asset class
Benefit plan assets	3,664	1,279
Level 1 and Level 2 | Fixed income and fixed income-related instruments
Benefit plan assets by asset class
Benefit plan assets	882	3,569
Level 1
Benefit plan assets by asset class
Benefit plan assets	1,873	2,001
Level 1 | Equities and equity-related instruments
Benefit plan assets by asset class
Benefit plan assets	1,061	840
Level 1 | Delta common stock
Benefit plan assets by asset class
Benefit plan assets	507	737
Level 1 | Cash equivalents
Benefit plan assets by asset class
Benefit plan assets	305	327
Level 1 | Fixed income and fixed income-related instruments
Benefit plan assets by asset class
Benefit plan assets	0	97
Level 2
Benefit plan assets by asset class
Benefit plan assets	4,300	4,473
Level 2 | Equities and equity-related instruments
Benefit plan assets by asset class
Benefit plan assets	59	49
Level 2 | Delta common stock
Benefit plan assets by asset class
Benefit plan assets	0	0
Level 2 | Cash equivalents
Benefit plan assets by asset class
Benefit plan assets	3,359	952
Level 2 | Fixed income and fixed income-related instruments
Benefit plan assets by asset class
Benefit plan assets	882	3,472
NAV
Benefit plan assets by asset class
Benefit plan assets	$ 10,427	$ 9,854

Employee Benefit Plans - Invest

Employee Benefit Plans - Investments Measured at NAV (Details) - NAV - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Investments measured at NAV
Fair value of investment measured at NAV	$ 10,427	$ 9,854
Hedge funds and hedge fund-related strategies
Investments measured at NAV
Fair value of investment measured at NAV	$ 5,474	$ 5,588
Hedge funds and hedge fund-related strategies | Minimum
Investments measured at NAV
Redemption notice period	2 days	2 days
Hedge funds and hedge fund-related strategies | Maximum
Investments measured at NAV
Redemption notice period	180 days	180 days
Commingled funds, private equity and private equity-related instruments
Investments measured at NAV
Fair value of investment measured at NAV	$ 2,136	$ 1,834
Unfunded commitments	$ 916
Commingled funds, private equity and private equity-related instruments | Minimum
Investments measured at NAV
Redemption notice period	3 days	2 days
Commingled funds, private equity and private equity-related instruments | Maximum
Investments measured at NAV
Redemption notice period	30 days	30 days
Fixed income and fixed income-related instruments
Investments measured at NAV
Fair value of investment measured at NAV	$ 1,118	$ 958
Unfunded commitments	$ 264
Fixed income and fixed income-related instruments | Minimum
Investments measured at NAV
Redemption notice period	15 days	15 days
Fixed income and fixed income-related instruments | Maximum
Investments measured at NAV
Redemption notice period	90 days	90 days
Real assets
Investments measured at NAV
Fair value of investment measured at NAV	$ 671	$ 758
Unfunded commitments	181
Other
Investments measured at NAV
Fair value of investment measured at NAV	$ 1,028	$ 716
Other | Minimum
Investments measured at NAV
Redemption notice period	2 days	2 days
Other | Maximum
Investments measured at NAV
Redemption notice period	90 days	90 days

Employee Benefit Plans - Narrat

Employee Benefit Plans - Narrative (Details) employee in Thousands, $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2020USD ($)employee	Dec. 31, 2020USD ($)employee	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Defined Benefit Plan Disclosure
Discount rate for 17-year amortization period of unfunded liability for frozen defined benefit plan (percent)		8.85%
Estimated funding by employer in next fiscal year		$ 500
Defined contribution plan costs		$ 805	$ 1,000	$ 925
Assumed healthcare plan pre age		65 years
Assumed healthcare plan post age		65 years
Weighted average expected long-term rate of return on plan assets (percent)		8.97%	8.97%	8.97%
Restructuring charges		$ 8,219	$ 0	$ 0
Profit sharing		$ 0	1,643	1,301
Voluntary early retirement and separation programs
Defined Benefit Plan Disclosure
Number of employees participating | employee	18	18
Restructuring charges	$ 3,400
Voluntary early retirement and separation programs | Special termination benefits
Defined Benefit Plan Disclosure
Special termination benefit charge	1,300
Voluntary early retirement and separation programs | Separation payments and healthcare benefits
Defined Benefit Plan Disclosure
Cash payments disbursed to participants		$ 720
Voluntary early retirement and separation programs | Unpaid vacation and other benefits
Defined Benefit Plan Disclosure
Cash payments disbursed to participants		250
Other Postretirement and Postemployment Benefits
Defined Benefit Plan Disclosure
Special termination benefit charge	1,300	1,260	0	$ 0
Special termination benefits	$ 1,300	$ 1,260	$ 0
Growth-seeking assets | Minimum
Defined Benefit Plan Disclosure
Plan assets, target allocations (percent)		30.00%
Growth-seeking assets | Maximum
Defined Benefit Plan Disclosure
Plan assets, target allocations (percent)		50.00%
Income-generating assets | Minimum
Defined Benefit Plan Disclosure
Plan assets, target allocations (percent)		25.00%
Income-generating assets | Maximum
Defined Benefit Plan Disclosure
Plan assets, target allocations (percent)		35.00%
Risk-diversifying assets | Minimum
Defined Benefit Plan Disclosure
Plan assets, target allocations (percent)		30.00%
Risk-diversifying assets | Maximum
Defined Benefit Plan Disclosure
Plan assets, target allocations (percent)		40.00%

Commitments and Contingencies -

Commitments and Contingencies - Aircraft Purchase Commitments and Contract Carrier Minimum Obligations (Details) $ in Millions	Dec. 31, 2020USD ($)
Future aircraft purchase commitments
Future commitments:
2021	$ 1,330
2022	2,470
2023	2,310
2024	2,960
2025	2,740
Thereafter	2,070
Total	13,880
Capacity purchase agreements
Future commitments:
2021	1,413
2022	1,372
2023	1,240
2024	1,209
2025	837
Thereafter	1,654
Total	$ 7,725

Commitments and Contingencies_2

Commitments and Contingencies - Aircraft Purchase Commitments by Fleet Type (Details) - Future aircraft purchase commitments	Dec. 31, 2020aircraftlease_commitment
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	224
A220-100
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	7
A220-300
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	45
A321-200
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	22
A321-200neo
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	100
A330-900neo
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	29
Number of lease commitments included in purchase commitment | lease_commitment	1
A350-900
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	20
CRJ-900
Future Purchase Commitments
Aircraft purchase commitments, minimum quantity required	1

Commitments and Contingencies_3

Commitments and Contingencies - Narrative (Details) $ in Millions	1 Months Ended		3 Months Ended	12 Months Ended			36 Months Ended
	May 31, 2020USD ($)aircraft	Jan. 31, 2020aircraft	Jun. 30, 2020USD ($)aircraft	Dec. 31, 2020USD ($)aircraft	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2022USD ($)
Future Purchase Commitments
Reduction in aircraft purchase commitments based on restructured order book				$ 2,000
Restructuring charges				8,219	$ 0	$ 0
Future aircraft purchase commitments
Future Purchase Commitments
Purchase commitments				$ 13,880
Forecast
Future Purchase Commitments
Reduction in aircraft purchase commitments based on restructured order book							$ 5,000
LATAM
Future Purchase Commitments
Restructuring charges	$ 62		$ 62
A350-900 | LATAM
Future Purchase Commitments
Number of purchase commitments assumed | aircraft		10		10
Number of aircraft in terminated purchase agreement | aircraft	4
A350-900 | LATAM | Future aircraft purchase commitments
Future Purchase Commitments
Number of purchase commitments assumed | aircraft				10
Number of aircraft in terminated purchase agreement | aircraft			4

Commitments and Contingencies_4

Commitments and Contingencies - Employees Under Collective Bargaining Agreements (Details)	Dec. 31, 2020employee
Other Commitments [Line Items]
Approximate number of active employees	74,000
Delta Pilots - Represented by Unions
Other Commitments [Line Items]
Approximate number of active employees	12,940
Delta Flight Superintendents (Dispatchers) - Represented by Unions
Other Commitments [Line Items]
Approximate number of active employees	350
Endeavor Air Pilots - Represented by Unions
Other Commitments [Line Items]
Approximate number of active employees	1,900
Endeavor Air Flight Attendants - Represented by Unions
Other Commitments [Line Items]
Approximate number of active employees	1,480

Commitments and Contingencies_5

Commitments and Contingencies - Employees Under Collective Bargaining Agreements Narrative (Details)	Dec. 31, 2020employee
Other Commitments [Line Items]
Approximate number of employees	74,000
Percentage of employees represented by unions under collective bargaining agreements	23.00%
Monroe refinery employees represented by United Steel Workers
Other Commitments [Line Items]
Approximate number of employees	190

Income Taxes - Components of In

Income Taxes - Components of Income Tax Benefit (Provision) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current tax benefit (provision):
Federal	$ 94	$ 94	$ 187
State and local	3	(39)	(26)
International	(5)	(13)	(13)
Deferred tax benefit (provision):
Federal	2,766	(1,343)	(1,226)
State and local	344	(130)	(138)
Income tax provision	$ 3,202	$ (1,431)	$ (1,216)

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Percent
U.S. federal statutory income tax rate	21.00%	21.00%	21.00%
State taxes, net of federal benefit	1.90%	2.30%	2.50%
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent	(2.60%)	0.70%	0.00%
Other	0.20%	(0.90%)	0.10%
Effective income tax rate	20.50%	23.10%	23.60%

Income Taxes - Deferred Taxes (

Income Taxes - Deferred Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 1,495	$ 560
Capital loss carryforward	483	0
Pension, postretirement and other benefits	2,956	2,241
Deferred revenue	1,797	1,667
Lease liabilities	2,185	1,510
Other	611	380
Valuation allowance	(460)	(58)
Total deferred tax assets	9,067	6,300
Deferred tax liabilities:
Depreciation	4,507	5,190
Operating lease assets	1,324	1,298
Intangible assets	1,076	1,049
Other	172	99
Total deferred tax liabilities	7,079	7,636
Net deferred tax assets (liabilities)	1,988
Net deferred tax assets (liabilities)		(1,336)
Net state deferred tax assets		120
Net federal deferred tax liabilities	$ 0	$ 1,456

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Operating loss carryforwards	$ 5,700
Net deferred tax asset	1,988
Valuation allowance	460	$ 58
Deferred income tax expense in AOCI that will not be recognized until obligation is fully extinguished	$ 750

Equity and Equity Compensation

Equity and Equity Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Capital stock, shares authorized (shares)	2,000,000,000
Common stock, shares authorized (shares)	1,500,000,000	1,500,000,000
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (shares)	500,000,000
Treasury stock weighted average cost per share (usd per share)	$ 28.23	$ 26.37
Number of shares authorized for issuance under the Plan (shares)	163,000,000
Capital shares reserved for future issuance (shares)	21,000,000
Equity compensation expense	$ 119	$ 161	$ 159
Compensation cost not yet recognized	$ 80
Outstanding stock option awards (shares)	5,400,000
Outstanding stock option awards exercisable, weighted average exercise price (usd per share)	$ 52.37
Number of exercisable stock option awards (shares)	2,400,000
Restricted stock awards
Class of Stock [Line Items]
Unvested restricted stock awards (shares)	2,200,000
Stock options
Class of Stock [Line Items]
Term of award (in years)	10 years
Delta Common Stock Warrants
Class of Stock [Line Items]
Number shares called by warrants (in shares)	6,700,000

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax
Beginning balance		$ 15,358	$ 13,687	$ 12,530
Changes in value (net of tax effect)		(1,252)	(415)	(287)
Changes in value, tax effect		(384)	(133)	(88)
Reclassifications into retained earnings (net of tax effect)				(106)
Reclassifications into retained earnings, tax effect				(61)
Reclassification into earnings (net of tax effect)		203	251	189
Reclassifications into earnings, tax effect		169	76	57
Ending balance		1,534	15,358	13,687
Deferred income tax expense in AOCI that will not be recognized until obligation is fully extinguished		750
Tax benefit		3,202	(1,431)	(1,216)
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax
Beginning balance		(7,989)	(7,825)	(7,621)
Beginning balance, tax effect		(1,549)	(1,492)	(1,400)
Ending balance		(9,038)	(7,989)	(7,825)
Ending balance, tax effect		(1,764)	(1,549)	(1,492)
Pension and Other Benefits Liabilities
AOCI Attributable to Parent, Net of Tax
Beginning balance		(8,095)	(7,925)	(7,812)
Changes in value (net of tax effect)		(1,269)	(422)	(294)
Reclassifications into retained earnings (net of tax effect)				0
Reclassification into earnings (net of tax effect)		286	252	181
Ending balance		(9,078)	(8,095)	(7,925)
Other
AOCI Attributable to Parent, Net of Tax
Beginning balance		106	100	85
Changes in value (net of tax effect)		17	7	7
Reclassifications into retained earnings (net of tax effect)				0
Reclassification into earnings (net of tax effect)		(83)	(1)	8
Ending balance		40	106	100
Other | Reclassification out of Accumulated Other Comprehensive Income [Member]
AOCI Attributable to Parent, Net of Tax
Tax benefit	$ 83
Available-for-Sale Investments
AOCI Attributable to Parent, Net of Tax
Beginning balance		0	0	106
Changes in value (net of tax effect)		0	0	0
Reclassifications into retained earnings (net of tax effect)				(106)
Reclassification into earnings (net of tax effect)		0	0	0
Ending balance		$ 0	$ 0	$ 0

Segments - Narrative (Details)

Segments - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Business Acquisition [Line Items]
Number of operating segments | segment	2
Operating revenue	$ 17,095	$ 47,007	$ 44,438
Intersegment Sales/Other | Exchanged products
Business Acquisition [Line Items]
Operating revenue	$ (1,472)	$ (3,963)	$ (3,596)

Segments - Schedule of Segment

Segments - Schedule of Segment Reporting (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information, Profit (Loss)
Operating revenue	$ 17,095	$ 47,007	$ 44,438
Operating income (loss)	(12,469)	6,618	5,264
Interest expense, net	929	301	311
Depreciation and amortization	2,312	2,581	2,329
Restructuring charges	8,219	0	0
Total assets	71,996	64,532	60,266
Capital expenditures	1,899	4,936	5,168
Operating Segments | Airline
Segment Reporting Information, Profit (Loss)
Operating revenue	15,945	46,910	43,890
Operating income (loss)	(12,253)	6,542	5,206
Interest expense, net	928	327	334
Depreciation and amortization	2,312	2,581	2,329
Restructuring charges	8,219
Total assets	70,548	62,793	58,561
Capital expenditures	1,879	4,880	5,005
Operating Segments | Refinery
Segment Reporting Information, Profit (Loss)
Operating revenue	3,143	5,558	5,458
Operating income (loss)	(216)	76	58
Interest expense, net	1	(26)	(23)
Depreciation and amortization	99	99	67
Restructuring charges	0
Total assets	1,448	1,739	1,705
Capital expenditures	20	56	163
Intersegment Sales/Other
Segment Reporting Information, Profit (Loss)
Depreciation and amortization	(99)	(99)	(67)
Intersegment Sales/Other | Sales to airline segment
Segment Reporting Information, Profit (Loss)
Operating revenue	(214)	(1,103)	(962)
Intersegment Sales/Other | Exchanged products
Segment Reporting Information, Profit (Loss)
Operating revenue	(1,472)	(3,963)	(3,596)
Intersegment Sales/Other | Sales of refined products
Segment Reporting Information, Profit (Loss)
Operating revenue	$ (307)	$ (395)	$ (352)

(Loss)_Earnings Per Share (Deta

(Loss)/Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net (loss)/income	$ (12,385)	$ 4,767	$ 3,935
Basic weighted average shares outstanding (shares)	636	651	691
Dilutive effect of share-based awards (shares)	0	2	3
Diluted weighted average shares outstanding (shares)	636	653	694
Basic (loss) earnings per share (usd per share)	$ (19.49)	$ 7.32	$ 5.69
Diluted (loss) earnings per share (usd per share)	$ (19.49)	$ 7.30	$ 5.67