United Airlines 10-Q 17 Apr 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 12, 2019
Document Information [Line Items]
Entity Registrant Name	United Continental Holdings, Inc.
Entity Central Index Key	0000100517
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Trading Symbol	UAL
Entity Common Stock, Shares Outstanding		263,129,397
United Airlines, Inc.
Document Information [Line Items]
Entity Registrant Name	United Airlines, Inc.
Entity Central Index Key	0000319687
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		1,000

Statements of Consolidated Oper

Statements of Consolidated Operations (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating revenue:
Revenue	$ 9,589	$ 9,032	[1]
Operating expense:
Salaries and related costs	2,873	2,726	[1]
Aircraft fuel	2,023	1,965	[1]
Regional capacity purchase	688	630	[1]
Landing fees and other rent	588	579	[1]
Depreciation and amortization	547	524	[1]
Aircraft maintenance materials and outside repairs	408	440	[1]
Distribution expenses	360	342	[1]
Aircraft rent	81	127	[1]
Special charges	18	40	[1]
Other operating expenses	1,508	1,397	[1]
Total operating expenses	9,094	8,770	[1]
Operating income	495	262	[1]
Nonoperating income (expense):
Interest expense	(188)	(162)	[1]
Interest capitalized	22	18	[1]
Interest income	29	17	[1]
Miscellaneous, net	9	47	[1]
Total nonoperating expense, net	(128)	(80)	[1]
Income before income taxes	367	182	[1]
Income tax expense	75	37	[1]
Net income	$ 292	$ 145	[1],[2],[3]
Earnings per share, basic and diluted (in dollars per share)	$ 1.09	$ 0.51	[1]
United Airlines, Inc.
Operating revenue:
Revenue	$ 9,589	$ 9,032	[4]
Operating expense:
Salaries and related costs	2,873	2,726	[4]
Aircraft fuel	2,023	1,965	[4]
Regional capacity purchase	688	630	[4]
Landing fees and other rent	588	579	[4]
Depreciation and amortization	547	524	[4]
Aircraft maintenance materials and outside repairs	408	440	[4]
Distribution expenses	360	342	[4]
Aircraft rent	81	127	[4]
Special charges	18	40	[4]
Other operating expenses	1,507	1,397	[4]
Total operating expenses	9,093	8,770	[4]
Operating income	496	262	[4]
Nonoperating income (expense):
Interest expense	(188)	(162)	[4]
Interest capitalized	22	18	[4]
Interest income	29	17	[4]
Miscellaneous, net	9	47	[4]
Total nonoperating expense, net	(128)	(80)	[4]
Income before income taxes	368	182	[4]
Income tax expense	75	37	[4]
Net income	293	145	[4],[5],[6]
Passenger revenue
Operating revenue:
Revenue	8,725	8,149	[1]
Passenger revenue | United Airlines, Inc.
Operating revenue:
Revenue	8,725	8,149	[4]
Cargo
Operating revenue:
Revenue	286	293	[1]
Cargo | United Airlines, Inc.
Operating revenue:
Revenue	286	293	[4]
Other operating revenue
Operating revenue:
Revenue	578	590	[1]
Other operating revenue | United Airlines, Inc.
Operating revenue:
Revenue	$ 578	$ 590	[4]
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[5]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[6]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.

Statements of Consolidated Comp

Statements of Consolidated Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net income	$ 292	$ 145	[1],[2],[3]
Other comprehensive income, net change related to:
Employee benefit plans, net of taxes	7	30	[2]
Investments and other, net of taxes	3	3	[2]
Total other comprehensive income, net	10	33	[2]
Total comprehensive income, net	302	178	[2]
United Airlines, Inc.
Net income	293	145	[4],[5],[6]
Other comprehensive income, net change related to:
Employee benefit plans, net of taxes	7	30	[5]
Investments and other, net of taxes	3	3	[5]
Total other comprehensive income, net	10	33	[5]
Total comprehensive income, net	$ 303	$ 178	[5]
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[5]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[6]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 1,848	$ 1,694	[1]
Short-term investments	2,219	2,256	[1]
Receivables, less allowance for doubtful accounts (2019 — $8; 2018 — $8)	1,789	1,426	[1]
Aircraft fuel, spare parts and supplies, less obsolescence allowance (2019 — $421; 2018 — $412)	972	985	[1]
Prepaid expenses and other	780	733	[1]
Total current assets	7,608	7,094	[1]
Operating property and equipment:
Flight equipment	33,705	32,599	[1]
Other property and equipment	7,165	6,889	[1]
Purchase deposits for flight equipment	1,455	1,177	[1]
Total operating property and equipment, at cost	42,325	40,665	[1]
Less — Accumulated depreciation and amortization	(13,739)	(13,266)	[1]
Total operating property and equipment, net	28,586	27,399	[1]
Operating lease right-of-use assets	5,065	5,262	[1]
Other assets:
Goodwill	4,523	4,523	[1]
Intangibles, less accumulated amortization (2019 — $1,395; 2018 — $1,380)	3,144	3,159	[1]
Restricted cash	103	105	[1]
Notes receivable, net	512	516	[1]
Investments in affiliates and other, net	1,098	966	[1]
Total other assets	9,380	9,269	[1]
Total assets	50,639	49,024	[1]
Current liabilities:
Advance ticket sales	6,006	4,381	[1]
Accounts payable	2,707	2,363	[1]
Frequent flyer deferred revenue	2,388	2,286	[1]
Accrued salaries and benefits	1,660	2,184	[1]
Current maturities of long-term debt	1,201	1,230	[1]
Current maturities of finance leases	133	123	[1]
Current maturities of operating leases	639	719	[1]
Other	601	553	[1]
Total current liabilities	15,335	13,839	[1]
Long-term debt	12,734	12,215	[1]
Long-term obligations under finance leases	236	224	[1]
Long-term obligations under operating leases	5,145	5,276	[1]
Other liabilities and deferred credits:
Frequent flyer deferred revenue	2,750	2,719	[1]
Postretirement benefit liability	1,287	1,295	[1]
Pension liability	1,454	1,576	[1]
Deferred income taxes	898	828	[1]
Other	998	1,010	[1]
Total other liabilities and deferred credits	7,387	7,428	[1]
Commitments and contingencies			[1]
Stockholders' equity:
Preferred stock	0	0	[1]
Common stock	3	3	[1]
Additional capital invested	6,080	6,120	[1]
Retained earnings	6,999	6,715	[1]
Stock held in treasury, at cost	(2,487)	(1,993)	[1]
Accumulated other comprehensive loss	(793)	(803)	[1]
Total stockholders' equity	9,802	10,042	[1],[2]
Total liabilities and stockholders' equity	50,639	49,024	[1]
United Airlines, Inc.
Current assets:
Cash and cash equivalents	1,842	1,688	[3]
Short-term investments	2,219	2,256	[3]
Receivables, less allowance for doubtful accounts (2019 — $8; 2018 — $8)	1,789	1,426	[3]
Aircraft fuel, spare parts and supplies, less obsolescence allowance (2019 — $421; 2018 — $412)	972	985	[3]
Prepaid expenses and other	780	733	[3]
Total current assets	7,602	7,088	[3]
Operating property and equipment:
Flight equipment	33,705	32,599	[3]
Other property and equipment	7,165	6,889	[3]
Purchase deposits for flight equipment	1,455	1,177	[3]
Total operating property and equipment, at cost	42,325	40,665	[3]
Less — Accumulated depreciation and amortization	(13,739)	(13,266)	[3]
Total operating property and equipment, net	28,586	27,399	[3]
Operating lease right-of-use assets	5,065	5,262	[3]
Other assets:
Goodwill	4,523	4,523	[3]
Intangibles, less accumulated amortization (2019 — $1,395; 2018 — $1,380)	3,144	3,159	[3]
Restricted cash	103	105	[3]
Notes receivable, net	512	516	[3]
Investments in affiliates and other, net	1,098	966	[3]
Total other assets	9,380	9,269	[3]
Total assets	50,633	49,018	[3]
Current liabilities:
Advance ticket sales	6,006	4,381	[3]
Accounts payable	2,707	2,363	[3]
Frequent flyer deferred revenue	2,388	2,286	[3]
Accrued salaries and benefits	1,660	2,184	[3]
Current maturities of long-term debt	1,201	1,230	[3]
Current maturities of finance leases	133	123	[3]
Current maturities of operating leases	639	719	[3]
Other	606	558	[3]
Total current liabilities	15,340	13,844	[3]
Long-term debt	12,734	12,215	[3]
Long-term obligations under finance leases	236	224	[3]
Long-term obligations under operating leases	5,145	5,276	[3]
Other liabilities and deferred credits:
Frequent flyer deferred revenue	2,750	2,719	[3]
Postretirement benefit liability	1,287	1,295	[3]
Pension liability	1,454	1,576	[3]
Deferred income taxes	925	855	[3]
Other	999	1,010	[3]
Total other liabilities and deferred credits	7,415	7,455	[3]
Commitments and contingencies			[3]
Stockholders' equity:
Common stock	0	0	[3]
Additional capital invested	84	598	[3]
Retained earnings	10,612	10,319	[3]
Accumulated other comprehensive loss	(793)	(803)	[3]
Receivable from related parties	(140)	(110)	[3]
Total stockholders' equity	9,763	10,004	[3],[4]
Total liabilities and stockholders' equity	$ 50,633	$ 49,018	[3]
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Receivables, allowance for doubtful accounts	$ 8	$ 8
Aircraft fuel, spare parts and supplies, obsolescence allowance	421	412
Intangibles, accumulated amortization	$ 1,395	$ 1,380
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares, authorized (in shares)	1,000,000,000	1,000,000,000
Common shares, outstanding (in shares)	264,271,125	269,914,769
United Airlines, Inc.
Receivables, allowance for doubtful accounts	$ 8	$ 8
Aircraft fuel, spare parts and supplies, obsolescence allowance	421	412
Intangibles, accumulated amortization	$ 1,395	$ 1,380
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares, authorized (in shares)	1,000	1,000
Common shares, issued (in shares)	1,000	1,000
Common shares, outstanding (in shares)	1,000	1,000

Condensed Statements of Consoli

Condensed Statements of Consolidated Cash Flows (Unaudited) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Cash Flows from Operating Activities:
Net cash provided by operating activities		$ 1,915	$ 1,709	[1]
Cash Flows from Investing Activities:
Capital expenditures		(1,609)	(944)	[1]
Purchases of short-term and other investments		(724)	(596)	[1]
Proceeds from sale of short-term and other investments		768	840	[1]
Loans made to others		0	(10)	[1]
Investment in affiliates		(27)	0	[1]
Other, net		12	15	[1]
Net cash used in investing activities		(1,580)	(695)	[1]
Cash Flows from Financing Activities:
Proceeds from issuance of long-term debt		646	673	[1]
Payments of long-term debt		(250)	(189)	[1]
Repurchases of common stock		(513)	(529)	[1]
Principal payments under finance leases		(20)	(18)	[1]
Capitalized financing costs		(17)	(16)	[1]
Other, net		(29)	(16)	[1]
Net cash used in financing activities		(183)	(95)	[1]
Net increase in cash, cash equivalents and restricted cash		152	919	[1]
Cash, cash equivalents and restricted cash at beginning of the period		1,799	1,591	[1]
Cash, cash equivalents and restricted cash at end of the period	[2]	1,951	2,510	[1]
Investing and Financing Activities Not Affecting Cash:
Property and equipment acquired through the issuance of debt		92	60	[1]
Operating lease conversions to finance lease		36	0	[1]
Right-of-use assets acquired through operating leases		51	103	[1]
Property and equipment acquired through finance leases		8	0	[1]
United Airlines, Inc.
Cash Flows from Operating Activities:
Net cash provided by operating activities		1,886	1,692	[3]
Cash Flows from Investing Activities:
Capital expenditures		(1,609)	(944)	[3]
Purchases of short-term investments and other investments		(724)	(596)	[3]
Proceeds from sale of short-term and other investments		768	840	[3]
Loans made to others		0	(10)	[3]
Investment in affiliates		(27)	0	[3]
Other, net		12	15	[3]
Net cash used in investing activities		(1,580)	(695)	[3]
Cash Flows from Financing Activities:
Proceeds from issuance of long-term debt		646	673	[3]
Dividend to UAL		(513)	(529)	[3]
Payments of long-term debt		(250)	(189)	[3]
Principal payments under finance leases		(20)	(18)	[3]
Capitalized financing costs		(17)	(16)	[3]
Other, net		0	1	[3]
Net cash used in financing activities		(154)	(78)	[3]
Net increase in cash, cash equivalents and restricted cash		152	919	[3]
Cash, cash equivalents and restricted cash at beginning of the period		1,793	1,585	[3]
Cash, cash equivalents and restricted cash at end of the period	[4]	1,945	2,504	[3]
Investing and Financing Activities Not Affecting Cash:
Property and equipment acquired through the issuance of debt		92	60	[3]
Operating lease conversions to finance lease		36	0	[3]
Right-of-use assets acquired through operating leases		51	103	[3]
Property and equipment acquired through finance leases		$ 8	$ 0	[3]
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[2]	The following table provides a reconciliation of cash, cash equivalents and restricted cash to amounts reported within the consolidated balance sheet:Cash and cash equivalents$1,848 $2,404Restricted cash (included in Prepaid expenses and other)— 11Restricted cash103 95Total cash, cash equivalents and restricted cash $1,951 $2,510
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[4]	The following table provides a reconciliation of cash, cash equivalents and restricted cash to amounts reported within the consolidated balance sheet:Cash and cash equivalents$1,842 $2,398Restricted cash (included in Prepaid expenses and other)— 11Restricted cash103 95Total cash, cash equivalents and restricted cash $1,945 $2,504

Condensed Statements of Conso_2

Condensed Statements of Consolidated Cash Flows (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2019		Dec. 31, 2018		Mar. 31, 2018
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	$ 1,848		$ 1,694	[1]	$ 2,404	[2]
Restricted cash (included in Prepaid expenses and other)	0				11	[2]
Restricted cash	103		105	[1]	95	[2]
Total cash, cash equivalents and restricted cash	1,951	[3]	1,799		2,510	[2],[3]
United Airlines, Inc.
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	1,842		1,688	[4]	2,398	[5]
Restricted cash (included in Prepaid expenses and other)	0				11	[5]
Restricted cash	103		105	[4]	95	[5]
Total cash, cash equivalents and restricted cash	$ 1,945	[6]	$ 1,793		$ 2,504	[5],[6]
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[3]	The following table provides a reconciliation of cash, cash equivalents and restricted cash to amounts reported within the consolidated balance sheet:Cash and cash equivalents$1,848 $2,404Restricted cash (included in Prepaid expenses and other)— 11Restricted cash103 95Total cash, cash equivalents and restricted cash $1,951 $2,510
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[5]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[6]	The following table provides a reconciliation of cash, cash equivalents and restricted cash to amounts reported within the consolidated balance sheet:Cash and cash equivalents$1,842 $2,398Restricted cash (included in Prepaid expenses and other)— 11Restricted cash103 95Total cash, cash equivalents and restricted cash $1,945 $2,504

Statements of Consolidated Stoc

Statements of Consolidated Stockholders' Equity - USD ($) $ in Millions		Total		United Airlines, Inc.		Common Stock		Additional Capital Invested		Additional Capital InvestedUnited Airlines, Inc.		Treasury Stock		Retained Earnings		Retained EarningsUnited Airlines, Inc.		Accumulated Other Comprehensive Income (Loss)		Accumulated Other Comprehensive Income (Loss)United Airlines, Inc.		Receivable from Related Parties, NetUnited Airlines, Inc.
Balance (in shares) at Dec. 31, 2017	[1]					287,000,000
Balance at Dec. 31, 2017		$ 8,788	[1]	$ 8,751	[2]	$ 3	[1]	$ 6,098	[1]	$ 1,787	[2]	$ (769)	[1]	$ 4,603	[1]	$ 8,201	[2]	$ (1,147)	[1]	$ (1,147)	[2]	$ (90)	[2]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		145	[1],[3],[4]	145	[2],[5],[6]									145	[1]	145	[2]
Other comprehensive income		33	[4]	33	[6]
Other comprehensive income		26		26														26		26
Dividend to UAL				(569)						(569)
Stock settled share-based compensation		15		15				15		15
Repurchases of common stock (in shares)						(7,800,000)
Repurchases of common stock		(569)										(569)
Net treasury stock issued for share-based awards (in shares)						200,000
Net treasury stock issued for share-based awards		(17)						(36)				24		(5)
Other				(18)												(7)				7		(18)
Balance (in shares) at Mar. 31, 2018	[1]					279,400,000
Balance at Mar. 31, 2018		$ 8,388	[1]	$ 8,350	[2]	$ 3	[1]	6,077	[1]	1,233	[2]	(1,314)	[1]	4,736	[1]	8,339	[2]	(1,114)	[1]	(1,114)	[2]	(108)	[2]
Balance (in shares) at Dec. 31, 2018		269,914,769		1,000		269,900,000	[1]
Balance at Dec. 31, 2018		$ 10,042	[1],[7]	$ 10,004	[2],[8]	$ 3	[1]	6,120	[1]	598	[2]	(1,993)	[1]	6,715	[1]	10,319	[2]	(803)	[1]	(803)	[2]	(110)	[2]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		292		293										292		293
Other comprehensive income		10		10														10		10
Dividend to UAL				(528)						(528)
Stock settled share-based compensation		14		14				14		14
Repurchases of common stock (in shares)						(6,100,000)
Repurchases of common stock		(527)										(527)
Net treasury stock issued for share-based awards (in shares)						500,000
Net treasury stock issued for share-based awards		$ (29)						(54)				33		(8)
Other				$ (30)																		(30)
Balance (in shares) at Mar. 31, 2019		264,271,125		1,000		264,300,000
Balance at Mar. 31, 2019		$ 9,802		$ 9,763		$ 3		$ 6,080		$ 84		$ (2,487)		$ 6,999		$ 10,612		$ (793)		$ (793)		$ (140)
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.The accompanying Combined Notes to Condensed Consolidated Financial Statements are an integral part of these statements.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[5]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[6]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[7]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[8]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

Recently Issued Accounting Stan

Recently Issued Accounting Standards	3 Months Ended
	Mar. 31, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
RECENTLY ISSUED ACCOUNTING STANDARDS	RECENTLY ISSUED ACCOUNTING STANDARDS The Company adopted Financial Accounting Standards Board ("FASB") Accounting Standards Codification Topic 842, Leases (the "New Lease Standard"), effective January 1, 2019. The Company used the modified retrospective approach for all leases existing at or commencing after January 1, 2017 and elected the package of transition practical expedients for expired or existing contracts, which does not require reassessment of: (1) whether any of our contracts are or contain leases, (2) lease classification and (3) initial direct costs. The New Lease Standard prescribes that an entity should recognize a right-of-use asset and a lease liability for all leases at the commencement date of each lease and recognize expenses on their income statements similar to the prior FASB Accounting Standards Codification Topic 840, Leases ("Topic 840"). The adoption of the New Lease Standard had the same impact on the financial statements of United as it had on the financial statements of UAL. The table below presents the impact of the adoption of the New Lease Standard on select accounts and captions of UAL's statement of consolidated operations for the first quarter of 2018 (in millions, except per share amounts): As Reported New Lease Standard Adjustments As Adjusted Regional capacity purchase $ 619 $ 11 $ 630 Landing fees and other rent 558 21 579 Depreciation and amortization 541 (17 ) 524 Interest expense (176 ) 14 (162 ) Interest capitalized 19 (1 ) 18 Net income 147 (2 ) 145 Earnings per share, basic and diluted 0.52 (0.01 ) 0.51 The expense for leases under the New Lease Standard will continue to be classified in their historical income statement captions (primarily in Aircraft rent, Landing fees and other rent and Regional capacity purchase in our statements of consolidated operations). The adoption of the New Lease Standard resulted in the recharacterization of certain leases from capital leases under Topic 840 to operating leases under the New Lease Standard. This change resulted in less depreciation and amortization and interest expense associated with capital leases offset by higher lease expense associated with operating leases. The recharacterization is associated with leases of certain airport facilities that were derecognized as part of the build-to-suit transition guidance under the New Lease Standard. The reduction in capitalized interest is also associated with the same airport facilities leases. The table below presents the impact of the adoption of the New Lease Standard on UAL's balance sheet accounts and captions as of December 31, 2018 (in millions): As Reported New Lease Standard Adjustments As Adjusted Receivables, less allowance for doubtful accounts $ 1,346 $ 80 $ 1,426 Prepaid expenses and other 913 (180 ) 733 Flight equipment, owned and finance leases (a) 32,636 (37 ) 32,599 Other property and equipment, owned and finance leases (a) 7,930 (1,041 ) 6,889 Less-Accumulated depreciation and amortization, owned and finance leases (a) (13,414 ) 148 (13,266 ) Operating lease right-of-use assets — 5,262 5,262 Current maturities of finance leases (a) 149 (26 ) 123 Current maturities of operating leases — 719 719 Other current liabilities 619 (66 ) 553 Long-term obligations under finance leases (a) 1,134 (910 ) 224 Long-term obligations under operating leases — 5,276 5,276 Deferred income taxes 814 14 828 Other long-term liabilities 1,832 (822 ) 1,010 Retained earnings 6,668 47 6,715 (a) Finance leases, under the New Lease Standard, are the equivalent of capital leases under Topic 840. The table below presents the impact of the adoption of the New Lease Standard on select line items of UAL's statement of consolidated cash flows for the first quarter of 2018 (in millions): As Reported New Lease Standard Adjustments As Adjusted Cash Flows from Operating Activities: Net cash provided by operating activities $ 1,733 $ (24 ) $ 1,709 Cash Flows from Investing Activities: Capital expenditures (979 ) 35 (944 ) Cash Flows from Financing Activities: Proceeds from issuance of long-term debt 696 (23 ) 673 Principal payments under finance leases (30 ) 12 (18 ) The adoption of the New Lease Standard primarily resulted in the recording of assets and obligations of our operating leases on our consolidated balance sheets. Certain amounts recorded for prepaid and accrued rent associated with historical operating leases were reclassified to the newly captioned Operating lease right-of-use assets in the consolidated balance sheets. Also, certain leases designated under Topic 840 as owned assets and capital leases are not considered to be assets under the New Lease Standard and have been removed from the consolidated balance sheets, along with the related capital lease liability, due to the leases having variable lease payments. In June 2016, the FASB issued Accounting Standards Update No. 2016-13, Financial Instruments—Credit Losses ("ASU 2016-13"). The main objective is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendments in this update replace the incurred loss methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to calculate credit loss estimates. For trade receivables, loans and held-to-maturity debt securities, entities will be required to estimate lifetime expected credit losses. For available-for-sale debt securities, entities will be required to recognize an allowance for credit losses rather than a reduction to the carrying value of the asset. The amendments are effective for public business entities for fiscal years and interim periods beginning after December 15, 2019. The Company is evaluating the impact the adoption of ASU 2016-13 will have on its consolidated financial statements.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
REVENUE	REVENUE Revenue by Geography. The following table presents operating revenue by geographic region (in millions): Three Months Ended March 31, 2019 2018 Domestic (U.S. and Canada) $ 5,875 $ 5,476 Atlantic 1,458 1,389 Pacific 1,281 1,231 Latin America 975 936 Total $ 9,589 $ 9,032 Ancillary Fees. The Company charges fees, separately from ticket sales, for certain ancillary services that are directly related to passengers' travel, such as ticket change fees, baggage fees, inflight amenities fees, and other ticket-related fees. These ancillary fees are part of the travel performance obligation and, as such, are recognized as passenger revenue when the travel occurs. The Company recorded $571 million and $497 million of ancillary fees within passenger revenue in the three months ended March 31, 2019 and 2018 , respectively. Advance Ticket Sales. All tickets sold at any given point of time have travel dates extending up to twelve months. The Company defers amounts related to future travel in its Advance ticket sales liability account. As a result, the balance of the Company's Advance ticket sales liability represents activity that will be recognized in the next twelve months. In the three months ended March 31, 2019 and 2018 , the Company recognized approximately $2.7 billion and $2.5 billion , respectively, of passenger revenue for tickets that were included in Advance ticket sales at the beginning of those periods. Frequent Flyer Accounting. The table below presents a roll forward of Frequent flyer deferred revenue (in millions): Three Months Ended March 31, 2019 2018 Total Frequent flyer deferred revenue - beginning balance $ 5,005 $ 4,783 Miles awarded 607 603 Travel miles redeemed (Passenger revenue) (438 ) (409 ) Non-travel miles redeemed (Other operating revenue) (36 ) (40 ) Total Frequent flyer deferred revenue - ending balance $ 5,138 $ 4,937 In the three months ended March 31, 2019 and 2018 , the Company recognized, in Other operating revenue, $473 million and $494 million , respectively, related to the marketing, advertising, non-travel miles redeemed (net of related costs) and other travel-related benefits of the mileage revenue associated with our various partner agreements including, but not limited to, our Chase co-brand agreement. The portion related to the MileagePlus miles awarded of the total amounts received from our various partner agreements is deferred and presented in the table above as an increase to the frequent flyer liability.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE The computations of UAL's basic and diluted earnings per share are set forth below (in millions, except per share amounts): Three Months Ended March 31, 2019 2018 Earnings available to common stockholders $ 292 $ 145 Basic weighted-average shares outstanding 267.0 283.9 Effect of employee stock awards 1.3 1.0 Diluted weighted-average shares outstanding 268.3 284.9 Earnings per share, basic and diluted $ 1.09 $ 0.51 In the three months ended March 31, 2019 , UAL repurchased approximately 6.3 million shares of UAL common stock in open market transactions for $527 million . As of March 31, 2019 , the Company had approximately $1.2 billion remaining to purchase shares under its share repurchase program. UAL may repurchase shares through the open market, privately negotiated transactions, block trades or accelerated share repurchase transactions from time to time in accordance with applicable securities laws. UAL will repurchase shares of UAL common stock subject to prevailing market conditions, and may discontinue such repurchases at any time. See Part II, Item 2, Unregistered Sales of Equity Securities and Use of Proceeds of this report for additional information.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The tables below present the components of the Company's accumulated other comprehensive income (loss), net of tax ("AOCI") (in millions): UAL Pension and Other Postretirement Liabilities Investments and Other Deferred Taxes Total Balance at December 31, 2018 $ (663 ) $ (4 ) $ (136 ) $ (803 ) Changes in value 5 5 (3 ) 7 Amounts reclassified to earnings 4 (a) — (1 ) 3 Balance at March 31, 2019 $ (654 ) $ 1 $ (140 ) $ (793 ) Balance at December 31, 2017 $ (1,102 ) $ (6 ) $ (39 ) $ (1,147 ) Changes in value 23 (4 ) (6 ) 13 Amounts reclassified to earnings 16 (a) — (3 ) 13 Amounts reclassified to retained earnings — 7 — 7 Balance at March 31, 2018 $ (1,063 ) $ (3 ) $ (48 ) $ (1,114 ) (a) This AOCI component is included in the computation of net periodic pension and other postretirement costs (See Note 6 to the financial statements included in Part I, Item 1 for additional information).

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Company's effective tax rate for the three months ended March 31, 2019 and 2018 was 20.4% and 20.3% , respectively. The effective tax rate represents a blend of federal, state and foreign taxes and includes the impact of certain nondeductible items and the impact of a change in the Company's mix of domestic and foreign earnings.

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2019
Employee-related Liabilities [Abstract]
EMPLOYEE BENEFIT PLANS	EMPLOYEE BENEFIT PLANS Defined Benefit Pension and Other Postretirement Benefit Plans. The Company's net periodic benefit cost includes the following components for the three months ended March 31 (in millions): Pension Benefits Other Postretirement Benefits Affected Line Item 2019 2018 2019 2018 Service cost $ 46 $ 57 $ 2 $ 3 Salaries and related costs Interest cost 57 54 15 15 Miscellaneous, net Expected return on plan assets (72 ) (73 ) — — Miscellaneous, net Amortization of unrecognized (gain) loss 29 33 (15 ) (8 ) Miscellaneous, net Amortization of prior service credit — — (10 ) (9 ) Miscellaneous, net Total $ 60 $ 71 $ (8 ) $ 1 During the three months ended March 31, 2019 , the Company contributed $150 million to its U.S. domestic tax-qualified defined benefit pension plans. Share-Based Compensation. In the three months ended March 31, 2019 , UAL granted share-based compensation awards pursuant to the United Continental Holdings, Inc. 2017 Incentive Compensation Plan. These share-based compensation awards include 0.5 million restricted stock units ("RSUs"), half of which are time-vested RSUs and half of which are performance-based RSUs. The time-vested RSUs vest pro-rata, on February 28th of each year, over a three -year period from the date of grant. The amount of performance-based RSUs vest based on the Company's relative improvement in pre-tax margin, as compared to a group of industry peers, for the three years ending December 31, 2021 . All RSUs are generally equity awards settled in stock for domestic employees and liability awards settled in cash for international employees. The cash payments are based on the 20 -day average closing price of UAL common stock immediately prior to the vesting date. The table below presents information related to share-based compensation (in millions): Three Months Ended March 31, 2019 2018 Share-based compensation expense $ 16 $ 17 March 31, 2019 December 31, 2018 Unrecognized share-based compensation $ 84 $ 68

Financial Instruments and Fair

Financial Instruments and Fair Value Measurements	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS	FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS The table below presents disclosures about the financial assets and liabilities measured at fair value on a recurring basis in UAL's financial statements (in millions): March 31, 2019 December 31, 2018 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Cash and cash equivalents $ 1,848 $ 1,848 $ — $ — $ 1,694 $ 1,694 $ — $ — Short-term investments: Corporate debt 1,014 — 1,014 — 1,023 — 1,023 — Asset-backed securities 745 — 745 — 746 — 746 — U.S. government and agency notes 108 — 108 — 108 — 108 — Certificates of deposit placed through an account registry service ("CDARS") 45 — 45 — 75 — 75 — Other fixed-income securities 118 — 118 — 116 — 116 — Other investments measured at net asset value ("NAV") 189 — — — 188 — — — Restricted cash 103 103 — — 105 105 — — Long-term investments: Equity securities 263 263 — — 249 249 — — Enhanced equipment trust certificates ("EETC") 16 — — 16 18 — — 18 Avianca Holdings S.A. ("AVH") Derivative Assets 14 — — 14 11 — — 11 Available-for-sale investment maturities - The short-term investments shown in the table above are classified as available-for-sale, with the exception of investments measured at NAV. As of March 31, 2019 , asset-backed securities have remaining maturities of less than one year to approximately 16 years, corporate debt securities have remaining maturities of less than one year to approximately three years and CDARS have maturities of less than one year. U.S. government and agency notes have maturities of approximately one year or less and other fixed-income securities have maturities of two years or less. The EETC securities mature in July 2019 . Restricted cash - Restricted cash primarily includes collateral for letters of credit and collateral associated with facility leases and other insurance related obligations. Equity securities - Equity securities represent United's investment in Azul Linhas Aéreas Brasileiras S.A. ("Azul"), consisting of a preferred equity stake of approximately 8% (approximately 2% of the total capital stock of Azul). The Company recognizes changes to the fair market value of its equity investment in Azul in Miscellaneous, net in its statements of consolidated operations. Synergy Term Loan - In November 2018, United, as lender, entered into a Term Loan Agreement (the "Synergy Loan Agreement") with affiliates of Synergy Aerospace Corporation ("Synergy"), as borrower and guarantor, respectively. Pursuant to the Synergy Loan Agreement, United provided a $456 million term loan to Synergy (the "Synergy Term Loan"), secured by a pledge of borrower's equity, as well as Synergy's 516 million shares of common stock of AVH, the parent company of Aerovías del Continente Americano S.A. AVH Derivative Assets - As part of the Synergy Loan Agreement and related agreements with AVH's significant minority shareholder, Kingsland Holdings Limited ("Kingsland"), United obtained AVH share call options, AVH share appreciation rights, and an AVH share-based upside sharing agreement (collectively, the "AVH Derivative Assets"). The AVH Derivative Assets are recorded at fair value as Other assets on the Company's balance sheet and are included in the table above. Changes in the fair value of the AVH Derivative Assets are recorded as part of Nonoperating income (expense): Miscellaneous, net on the Company's statements of consolidated operations. Investments presented in the table above have the same fair value as their carrying value. The table below presents the carrying values and estimated fair values of financial instruments not presented in the tables above (in millions): March 31, 2019 December 31, 2018 Carrying Amount Fair Value Carrying Amount Fair Value Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Long-term debt $ 13,935 $ 14,136 $ — $ 10,307 $ 3,829 $ 13,445 $ 13,450 $ — $ 9,525 $ 3,925 Synergy Term Loan 480 422 — — 422 478 422 — — 422 Fair value of the financial instruments included in the tables above was determined as follows: Description Fair Value Methodology Cash and cash equivalents The carrying amounts approximate fair value because of the short-term maturity of these assets. Short-term investments, Equity securities, EETC and Restricted cash Fair value is based on (a) the trading prices of the investment or similar instruments, (b) an income approach, which uses valuation techniques to convert future amounts into a single present amount based on current market expectations about those future amounts when observable trading prices are not available, or (c) broker quotes obtained by third-party valuation services. Other investments measured at NAV In accordance with the relevant accounting standards, certain investments that are measured at fair value using the NAV per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the statement of financial position. The investments measured using NAV are shares of mutual funds that invest in fixed-income instruments including bonds, debt securities, and other similar instruments issued by various U.S. and non-U.S. public- or private-sector entities. The Company can redeem its shares at any time at NAV subject to a three-day settlement period. Long-term debt Fair values were based on either market prices or the discounted amount of future cash flows using our current incremental rate of borrowing for similar liabilities or assets. Synergy Term Loan and AVH Derivative Assets Fair values are calculated using a Monte Carlo simulation approach. Unobservable inputs include expected volatility, expected dividend yield and control and acquisition premiums.

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
LEASES	LEASES United leases aircraft, airport passenger terminal space, aircraft hangars and related maintenance facilities, cargo terminals, other airport facilities, other commercial real estate, office and computer equipment and vehicles, among other items. Certain of these leases include provisions for variable lease payments which are based on several factors, including, but not limited to, relative leased square footage, available seat miles, enplaned passengers, passenger facility charges, terminal equipment usage fees, departures, and airports’ annual operating budgets. Due to the variable nature of the rates, these leases are not recorded on our balance sheet as a right-of-use asset and lease liability. For leases with terms greater than 12 months, we record the related asset and lease liability at the present value of lease payments over the lease term. Leases with an initial term of 12 months or less with purchase options or extension options that are not reasonably certain to be exercised are not recorded on the balance sheet; we recognize lease expense for these leases on a straight-line basis over the term of the lease. We combine lease and non-lease components, such as common area maintenance costs, in calculating the right-of-use assets and lease liabilities for all asset groups except for our capacity purchase agreements ("CPAs"), which contain embedded leases for regional aircraft. In addition to the lease component cost for regional aircraft, our CPAs also include non-lease components primarily related to the regional carriers’ operating costs incurred in providing regional aircraft services. We allocate consideration separately for the lease components and non-lease components of each CPA based on their relative standalone values. Lease Cost . The Company's lease cost for the three months ended March 31 included the following components (in millions): 2019 2018 Operating lease cost $ 272 $ 326 Variable and short-term lease cost 606 611 Amortization of finance lease assets 18 23 Interest on finance lease liabilities 27 5 Sublease income (8 ) (10 ) Total lease cost $ 915 $ 955 Lease terms and commitments . United's leases include aircraft and non-aircraft leases. Aircraft operating leases relate to leases of 122 mainline and 341 regional aircraft while finance leases relate to leases of 30 mainline and 76 regional aircraft. United's aircraft leases have remaining lease terms of 2 months to 10 years with expiration dates ranging from 2019 through 2029 . Under the terms of most aircraft leases, United has the right to purchase the aircraft at the end of the lease term, in some cases at fair market value, and in others, at a percentage of cost. Non-aircraft leases have remaining lease terms of 1 month to 34 years , with expiration dates ranging from 2019 through 2053 . The table below summarizes the Company's scheduled future minimum lease payments under operating and finance leases, recorded on the balance sheet, as of March 31, 2019 (in millions): Operating Leases Finance Leases Last nine months of 2019 $ 662 $ 195 2020 985 96 2021 763 74 2022 630 47 2023 617 33 After 2023 4,252 69 Minimum lease payments 7,909 514 Imputed interest 2,125 145 Present value of minimum lease payments 5,784 369 Less: current maturities of lease obligations (639 ) (133 ) Long-term lease obligations $ 5,145 $ 236 As of March 31, 2019 , we have additional leases that have not yet commenced with an aggregate value of approximately $140 million . These leases will commence between 2019 and 2020 with lease terms of up to 34 years . To the extent a lease agreement includes an extension option that is reasonably certain to be exercised, we have recognized those amounts as part of our right-of-use assets and lease liabilities. Our lease agreements do not provide a readily determinable implicit rate nor is it available to us from our lessors. Instead, we estimate United's incremental borrowing rate based on information available at lease commencement in order to discount lease payments to present value. The table below presents additional information related to our leases as of March 31 : 2019 2018 Weighted-average remaining lease term - finance leases 5 years 5 years Weighted-average remaining lease term - operating leases 10 years 10 years Weighted-average discount rate - finance leases 50.5 % (a) 6.7 % Weighted-average discount rate - operating leases 5.2 % 5.0 % (a) During the third quarter of 2018, United entered into an agreement with the lessor of 54 Embraer ERJ 145 aircraft to purchase those aircraft in 2019. The provisions of these lease agreements resulted in a change in accounting classification of these leases from operating leases to finance leases up until the purchase date. The discount rates used for these leases were adjusted so that the present value of lease payments did not exceed the fair value of the asset being recognized. The table below presents supplemental cash flow information related to leases during the three months ended March 31 : 2019 2018 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 285 $ 279 Operating cash flows for finance leases 24 5 Financing cash flows for finance leases 20 18

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Commitments. As of March 31, 2019 , United had firm commitments and options to purchase aircraft from The Boeing Company ("Boeing"), Airbus S.A.S. ("Airbus") and Embraer S.A. ("Embraer") presented in the table below: Aircraft Type Number of Firm Airbus A350 45 Boeing 737 MAX 171 Boeing 777-300ER 4 Boeing 787 20 Embraer E175 25 (a) United also has options and purchase rights for additional aircraft. The aircraft listed in the table above are scheduled for delivery through 2027 . To the extent the Company and the aircraft manufacturers with whom the Company has existing orders for new aircraft agree to modify the contracts governing those orders, the amount and timing of the Company's future capital commitments could change. For the remainder of 2019, the Company is scheduled to take delivery of 25 Embraer E175 aircraft, 16 Boeing 737 MAX aircraft, 4 Boeing 787 aircraft and 2 Boeing 777-300ER aircraft. In 2020, the Company is scheduled to take delivery of 28 Boeing 737 MAX aircraft, 15 Boeing 787 aircraft and 2 Boeing 777-300ER aircraft. United also has agreements to purchase 20 used Airbus A319 aircraft with expected delivery dates through 2022 . During the third quarter of 2018, United entered into an agreement with the lessor of 54 Embraer ERJ 145 aircraft to purchase those aircraft in 2019. On March 13, 2019 the Federal Aviation Administration issued an emergency order prohibiting the operation of Boeing 737 MAX series airplanes by U.S. certified operators. As a result, the Company grounded all 14 Boeing 737 MAX 9 aircraft in its fleet. Prior to the grounding, the Company operated approximately 50 flights a day on these aircraft, and expected, given the delivery schedule, to operate approximately 110 flights a day by the end of the year. The Company has proactively managed the ongoing effects of this grounding. Through a combination of spare aircraft and rebooking customers, the Company has experienced a modest operational and financial impact as of March 31, 2019 as a result of this grounding. However, the operational and financial impact could increase based on a number of factors, including, among others, the period of time the aircraft are unavailable, the availability of replacement aircraft, to the extent needed, and the circumstances of any reintroduction of the grounded aircraft to service. The table below summarizes United's commitments as of March 31, 2019 , which include aircraft and related spare engines, aircraft improvements and all non-aircraft capital commitments: (in billions) Last nine months of 2019 $ 2.5 2020 5.4 2021 3.7 2022 3.1 2023 2.0 After 2023 7.0 $ 23.7 Guarantees. As of March 31, 2019 , United is the guarantor of approximately $1.9 billion in aggregate principal amount of tax-exempt special facilities revenue bonds and interest thereon. These bonds, issued by various airport municipalities, are payable solely from rentals paid under long-term agreements with the respective governing bodies. The leasing arrangements associated with these obligations are accounted for as operating leases recognized on the Company's balance sheet with the associated expense recorded on a straight-line basis resulting in ratable accrual of the lease obligation over the expected lease term. The obligations associated with these tax-exempt special facilities revenue bonds are included in our lease commitments disclosed in Note 8 of this report. All of these bonds are due between 2019 and 2038 . In connection with funding the Synergy Loan Agreement, the Company entered into an agreement with AVH's significant minority shareholder, Kingsland, pursuant to which, in return for Kingsland's pledge of its 144.8 million shares of AVH common stock (equivalent to 18.1 million American Depositary Receipts ("ADRs")) and its consent to Synergy's pledge of its AVH common stock to United under the Synergy Loan Agreement, United (1) granted to Kingsland the right to put its shares of AVH common stock to United at market price on the fifth anniversary of the Synergy Loan Agreement, and (2) guaranteed Synergy's obligation to pay Kingsland (which amount, if paid by United, will increase United's secured loan to Synergy by such amount) if the market price of AVH common stock on the fifth anniversary is less than $12 per ADR on the New York Stock Exchange, for an aggregate maximum possible combined put payment and guarantee amount on the fifth anniversary of $217 million . Accordingly, the Company recorded a liability of $31 million for the fair value of its guarantee to loan additional funds to Synergy if required. Any additional loans to Synergy would be collateralized by Synergy's shares of AVH stock and other collateral. Increased Cost Provisions. In United's financing transactions that include loans, United typically agrees to reimburse lenders for any reduced returns with respect to the loans due to any change in capital requirements and, in the case of loans in which the interest rate is based on the London Interbank Offered Rate, for certain other increased costs that the lenders incur in carrying these loans as a result of any change in law, subject, in most cases, to obligations of the lenders to take certain limited steps to mitigate the requirement for, or the amount of, such increased costs. At March 31, 2019 , the Company had $3.4 billion of floating rate debt and $18 million of fixed rate debt with remaining terms of up to 12 years that are subject to these increased cost provisions. In several financing transactions involving loans or leases from non-U.S. entities, with remaining terms of up to 12 years and an aggregate balance of $3.2 billion , the Company bears the risk of any change in tax laws that would subject loan or lease payments thereunder to non-U.S. entities to withholding taxes, subject to customary exclusions. As of March 31, 2019 , United is the guarantor of $142 million of aircraft mortgage debt issued by one of United's regional carriers. The aircraft mortgage debt is subject to similar increased cost provisions as described above for the Company's debt, and the Company would potentially be responsible for those costs under the guarantees. Labor Negotiations. As of March 31, 2019 , the Company had approximately 93,000 employees, of whom approximately 84% were represented by various U.S. labor organizations. On February 1, 2019, the collective bargaining agreement with the Air Line Pilots Association ("ALPA"), the union representing United’s pilots, became amendable. The Company and ALPA are in negotiations for an amended agreement. The Company and UNITE HERE, the labor union representing United's Catering Operations employees, started negotiations for a first collective bargaining agreement in March 2019.

Debt

Debt	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
DEBT	DEBT As of March 31, 2019 , UAL and United were in compliance with their respective debt covenants. As of March 31, 2019 , United had its entire capacity of $2.0 billion available under the revolving credit facility of the Amended and Restated Credit and Guaranty Agreement. EETCs . In February 2019, United created two new EETC pass-through trusts, each of which issued pass-through certificates. The proceeds of the issuance of the pass-through certificates are used to purchase equipment notes issued by United and secured by its aircraft. The Company records the debt obligation upon issuance of the equipment notes rather than upon the initial issuance of the pass-through certificates. The pass-through certificates represent fractional undivided interests in the respective pass-through trusts and are not obligations of United. The payment obligations under the equipment notes are those of United. Proceeds received from the sale of pass-through certificates are initially held by a depositary in escrow for the benefit of the certificate holders until United issues equipment notes to the trust, which purchases such notes with a portion of the escrowed funds. These escrowed funds are not guaranteed by United and are not reported as debt on our consolidated balance sheet because the proceeds held by the depositary are not United's assets. Certain details of the pass-through trusts with proceeds received from issuance of debt in 2019 are as follows (in millions, except stated interest rate): EETC Date Class Principal Final expected distribution date Stated interest rate Total debt recorded Proceeds received from issuance of debt during 2019 Remaining proceeds from issuance of debt to be received in future periods February 2019 AA $ 717 August 2031 4.15% $ 522 $ 522 $ 195 February 2019 A 296 August 2031 4.55% 216 216 80 $ 1,013 $ 738 $ 738 $ 275 The table below presents the Company's contractual principal payments (not including debt discount or debt issuance costs) at March 31, 2019 under then-outstanding long-term debt agreements (in millions): Last nine months of 2019 $ 979 2020 1,344 2021 1,338 2022 1,690 2023 740 After 2023 8,033 $ 14,124

Special Charges and Mark-to-Mar

Special Charges and Mark-to-Market ("MTM") Adjustments	3 Months Ended
	Mar. 31, 2019
Other Income and Expenses [Abstract]
SPECIAL CHARGES AND MARK-TO-MARKET (MTM) ADJUSTMENTS	SPECIAL CHARGES AND MARK-TO-MARKET ("MTM") ADJUSTMENTS For the three months ended March 31, special charges and MTM adjustments consisted of the following (in millions): Three Months Ended Operating: 2019 2018 Impairment of assets $ 8 $ 23 Severance and benefit costs 6 14 (Gains) losses on sale of assets and other special charges 4 3 Total operating special charges 18 40 Nonoperating MTM gains on financial instruments (17 ) (45 ) Total special charges and MTM gains on financial instruments 1 (5 ) Income tax expense — 1 Total special charges and MTM gains on financial instruments, net of income tax $ 1 $ (4 ) During the three months ended March 31, 2019 , the Company recorded an $8 million f air value adjustment for aircraft purchased off lease. During the three months ended March 31, 2019 , the Company recorded severance and benefit costs related to a voluntary early-out program for its technicians and related employees represented by the International Brotherhood of Teamsters (the "IBT") of $2 million . In the first quarter of 2017 , approximately 1,000 technicians and related employees elected to voluntarily separate from the Company and received a severance payment, with a maximum value of $100,000 per participant, based on years of service, with retirement dates through early 2019. Also during the three months ended March 31, 2019 , the Company recorded management severance of $4 million . During the three months ended March 31, 2019 , the Company recorded gains of $14 million for the change in market value of its investment in Azul. Also, the Company recorded gains of $3 million for the change in fair value of certain derivative assets related to equity of AVH. For equity investments and derivative assets subject to MTM accounting, the Company records gains and losses as part of Nonoperating income (expense): Miscellaneous, net in its statements of consolidated operations. During the three months ended March 31, 2018 , the Company recorded a $23 million fair value adjustment for aircraft purchased off lease and impairments related to certain fleet types and certain international slots no longer in use. During the three months ended March 31, 2018 , the Company recorded severance and benefit costs related to the early out program described above and management severance of $8 million and $6 million , respectively. During the three months ended March 31, 2018, the Company recorded a gain of $45 million for the change in market value of its investment in Azul.

Recently Issued Accounting St_2

Recently Issued Accounting Standards (Policies)	3 Months Ended
	Mar. 31, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recently Issued Accounting Standards	The Company adopted Financial Accounting Standards Board ("FASB") Accounting Standards Codification Topic 842, Leases (the "New Lease Standard"), effective January 1, 2019. The Company used the modified retrospective approach for all leases existing at or commencing after January 1, 2017 and elected the package of transition practical expedients for expired or existing contracts, which does not require reassessment of: (1) whether any of our contracts are or contain leases, (2) lease classification and (3) initial direct costs. The New Lease Standard prescribes that an entity should recognize a right-of-use asset and a lease liability for all leases at the commencement date of each lease and recognize expenses on their income statements similar to the prior FASB Accounting Standards Codification Topic 840, Leases ("Topic 840"). The adoption of the New Lease Standard had the same impact on the financial statements of United as it had on the financial statements of UAL. The table below presents the impact of the adoption of the New Lease Standard on select accounts and captions of UAL's statement of consolidated operations for the first quarter of 2018 (in millions, except per share amounts): As Reported New Lease Standard Adjustments As Adjusted Regional capacity purchase $ 619 $ 11 $ 630 Landing fees and other rent 558 21 579 Depreciation and amortization 541 (17 ) 524 Interest expense (176 ) 14 (162 ) Interest capitalized 19 (1 ) 18 Net income 147 (2 ) 145 Earnings per share, basic and diluted 0.52 (0.01 ) 0.51 The expense for leases under the New Lease Standard will continue to be classified in their historical income statement captions (primarily in Aircraft rent, Landing fees and other rent and Regional capacity purchase in our statements of consolidated operations). The adoption of the New Lease Standard resulted in the recharacterization of certain leases from capital leases under Topic 840 to operating leases under the New Lease Standard. This change resulted in less depreciation and amortization and interest expense associated with capital leases offset by higher lease expense associated with operating leases. The recharacterization is associated with leases of certain airport facilities that were derecognized as part of the build-to-suit transition guidance under the New Lease Standard. The reduction in capitalized interest is also associated with the same airport facilities leases. The table below presents the impact of the adoption of the New Lease Standard on UAL's balance sheet accounts and captions as of December 31, 2018 (in millions): As Reported New Lease Standard Adjustments As Adjusted Receivables, less allowance for doubtful accounts $ 1,346 $ 80 $ 1,426 Prepaid expenses and other 913 (180 ) 733 Flight equipment, owned and finance leases (a) 32,636 (37 ) 32,599 Other property and equipment, owned and finance leases (a) 7,930 (1,041 ) 6,889 Less-Accumulated depreciation and amortization, owned and finance leases (a) (13,414 ) 148 (13,266 ) Operating lease right-of-use assets — 5,262 5,262 Current maturities of finance leases (a) 149 (26 ) 123 Current maturities of operating leases — 719 719 Other current liabilities 619 (66 ) 553 Long-term obligations under finance leases (a) 1,134 (910 ) 224 Long-term obligations under operating leases — 5,276 5,276 Deferred income taxes 814 14 828 Other long-term liabilities 1,832 (822 ) 1,010 Retained earnings 6,668 47 6,715 (a) Finance leases, under the New Lease Standard, are the equivalent of capital leases under Topic 840. The table below presents the impact of the adoption of the New Lease Standard on select line items of UAL's statement of consolidated cash flows for the first quarter of 2018 (in millions): As Reported New Lease Standard Adjustments As Adjusted Cash Flows from Operating Activities: Net cash provided by operating activities $ 1,733 $ (24 ) $ 1,709 Cash Flows from Investing Activities: Capital expenditures (979 ) 35 (944 ) Cash Flows from Financing Activities: Proceeds from issuance of long-term debt 696 (23 ) 673 Principal payments under finance leases (30 ) 12 (18 ) The adoption of the New Lease Standard primarily resulted in the recording of assets and obligations of our operating leases on our consolidated balance sheets. Certain amounts recorded for prepaid and accrued rent associated with historical operating leases were reclassified to the newly captioned Operating lease right-of-use assets in the consolidated balance sheets. Also, certain leases designated under Topic 840 as owned assets and capital leases are not considered to be assets under the New Lease Standard and have been removed from the consolidated balance sheets, along with the related capital lease liability, due to the leases having variable lease payments. In June 2016, the FASB issued Accounting Standards Update No. 2016-13, Financial Instruments—Credit Losses ("ASU 2016-13"). The main objective is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendments in this update replace the incurred loss methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to calculate credit loss estimates. For trade receivables, loans and held-to-maturity debt securities, entities will be required to estimate lifetime expected credit losses. For available-for-sale debt securities, entities will be required to recognize an allowance for credit losses rather than a reduction to the carrying value of the asset. The amendments are effective for public business entities for fiscal years and interim periods beginning after December 15, 2019. The Company is evaluating the impact the adoption of ASU 2016-13 will have on its consolidated financial statements.
Fair Value of Financial Instruments	Fair value of the financial instruments included in the tables above was determined as follows: Description Fair Value Methodology Cash and cash equivalents The carrying amounts approximate fair value because of the short-term maturity of these assets. Short-term investments, Equity securities, EETC and Restricted cash Fair value is based on (a) the trading prices of the investment or similar instruments, (b) an income approach, which uses valuation techniques to convert future amounts into a single present amount based on current market expectations about those future amounts when observable trading prices are not available, or (c) broker quotes obtained by third-party valuation services. Other investments measured at NAV In accordance with the relevant accounting standards, certain investments that are measured at fair value using the NAV per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the statement of financial position. The investments measured using NAV are shares of mutual funds that invest in fixed-income instruments including bonds, debt securities, and other similar instruments issued by various U.S. and non-U.S. public- or private-sector entities. The Company can redeem its shares at any time at NAV subject to a three-day settlement period. Long-term debt Fair values were based on either market prices or the discounted amount of future cash flows using our current incremental rate of borrowing for similar liabilities or assets. Synergy Term Loan and AVH Derivative Assets Fair values are calculated using a Monte Carlo simulation approach. Unobservable inputs include expected volatility, expected dividend yield and control and acquisition premiums.

Recently Issued Accounting St_3

Recently Issued Accounting Standards (Tables)	3 Months Ended
	Mar. 31, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Impact of the Adoption of the New Lease Standard	The table below presents the impact of the adoption of the New Lease Standard on UAL's balance sheet accounts and captions as of December 31, 2018 (in millions): As Reported New Lease Standard Adjustments As Adjusted Receivables, less allowance for doubtful accounts $ 1,346 $ 80 $ 1,426 Prepaid expenses and other 913 (180 ) 733 Flight equipment, owned and finance leases (a) 32,636 (37 ) 32,599 Other property and equipment, owned and finance leases (a) 7,930 (1,041 ) 6,889 Less-Accumulated depreciation and amortization, owned and finance leases (a) (13,414 ) 148 (13,266 ) Operating lease right-of-use assets — 5,262 5,262 Current maturities of finance leases (a) 149 (26 ) 123 Current maturities of operating leases — 719 719 Other current liabilities 619 (66 ) 553 Long-term obligations under finance leases (a) 1,134 (910 ) 224 Long-term obligations under operating leases — 5,276 5,276 Deferred income taxes 814 14 828 Other long-term liabilities 1,832 (822 ) 1,010 Retained earnings 6,668 47 6,715 (a) Finance leases, under the New Lease Standard, are the equivalent of capital leases under Topic 840. The table below presents the impact of the adoption of the New Lease Standard on select line items of UAL's statement of consolidated cash flows for the first quarter of 2018 (in millions): As Reported New Lease Standard Adjustments As Adjusted Cash Flows from Operating Activities: Net cash provided by operating activities $ 1,733 $ (24 ) $ 1,709 Cash Flows from Investing Activities: Capital expenditures (979 ) 35 (944 ) Cash Flows from Financing Activities: Proceeds from issuance of long-term debt 696 (23 ) 673 Principal payments under finance leases (30 ) 12 (18 ) The table below presents the impact of the adoption of the New Lease Standard on select accounts and captions of UAL's statement of consolidated operations for the first quarter of 2018 (in millions, except per share amounts): As Reported New Lease Standard Adjustments As Adjusted Regional capacity purchase $ 619 $ 11 $ 630 Landing fees and other rent 558 21 579 Depreciation and amortization 541 (17 ) 524 Interest expense (176 ) 14 (162 ) Interest capitalized 19 (1 ) 18 Net income 147 (2 ) 145 Earnings per share, basic and diluted 0.52 (0.01 ) 0.51

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Passenger Revenue by Geographic Region	The following table presents operating revenue by geographic region (in millions): Three Months Ended March 31, 2019 2018 Domestic (U.S. and Canada) $ 5,875 $ 5,476 Atlantic 1,458 1,389 Pacific 1,281 1,231 Latin America 975 936 Total $ 9,589 $ 9,032
Roll Forward of Frequent Flyer Deferred Revenue	The table below presents a roll forward of Frequent flyer deferred revenue (in millions): Three Months Ended March 31, 2019 2018 Total Frequent flyer deferred revenue - beginning balance $ 5,005 $ 4,783 Miles awarded 607 603 Travel miles redeemed (Passenger revenue) (438 ) (409 ) Non-travel miles redeemed (Other operating revenue) (36 ) (40 ) Total Frequent flyer deferred revenue - ending balance $ 5,138 $ 4,937

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Share	The computations of UAL's basic and diluted earnings per share are set forth below (in millions, except per share amounts): Three Months Ended March 31, 2019 2018 Earnings available to common stockholders $ 292 $ 145 Basic weighted-average shares outstanding 267.0 283.9 Effect of employee stock awards 1.3 1.0 Diluted weighted-average shares outstanding 268.3 284.9 Earnings per share, basic and diluted $ 1.09 $ 0.51

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Components of Accumulated Other Comprehensive Income, Net of Tax	The tables below present the components of the Company's accumulated other comprehensive income (loss), net of tax ("AOCI") (in millions): UAL Pension and Other Postretirement Liabilities Investments and Other Deferred Taxes Total Balance at December 31, 2018 $ (663 ) $ (4 ) $ (136 ) $ (803 ) Changes in value 5 5 (3 ) 7 Amounts reclassified to earnings 4 (a) — (1 ) 3 Balance at March 31, 2019 $ (654 ) $ 1 $ (140 ) $ (793 ) Balance at December 31, 2017 $ (1,102 ) $ (6 ) $ (39 ) $ (1,147 ) Changes in value 23 (4 ) (6 ) 13 Amounts reclassified to earnings 16 (a) — (3 ) 13 Amounts reclassified to retained earnings — 7 — 7 Balance at March 31, 2018 $ (1,063 ) $ (3 ) $ (48 ) $ (1,114 ) (a) This AOCI component is included in the computation of net periodic pension and other postretirement costs (See Note 6 to the financial statements included in Part I, Item 1 for additional information).

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2019
Employee-related Liabilities [Abstract]
Components of Net Periodic Benefit Cost	The Company's net periodic benefit cost includes the following components for the three months ended March 31 (in millions): Pension Benefits Other Postretirement Benefits Affected Line Item 2019 2018 2019 2018 Service cost $ 46 $ 57 $ 2 $ 3 Salaries and related costs Interest cost 57 54 15 15 Miscellaneous, net Expected return on plan assets (72 ) (73 ) — — Miscellaneous, net Amortization of unrecognized (gain) loss 29 33 (15 ) (8 ) Miscellaneous, net Amortization of prior service credit — — (10 ) (9 ) Miscellaneous, net Total $ 60 $ 71 $ (8 ) $ 1
Information Related to Share-Based Compensation	The table below presents information related to share-based compensation (in millions): Three Months Ended March 31, 2019 2018 Share-based compensation expense $ 16 $ 17 March 31, 2019 December 31, 2018 Unrecognized share-based compensation $ 84 $ 68

Financial Instruments and Fai_2

Financial Instruments and Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	The table below presents disclosures about the financial assets and liabilities measured at fair value on a recurring basis in UAL's financial statements (in millions): March 31, 2019 December 31, 2018 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Cash and cash equivalents $ 1,848 $ 1,848 $ — $ — $ 1,694 $ 1,694 $ — $ — Short-term investments: Corporate debt 1,014 — 1,014 — 1,023 — 1,023 — Asset-backed securities 745 — 745 — 746 — 746 — U.S. government and agency notes 108 — 108 — 108 — 108 — Certificates of deposit placed through an account registry service ("CDARS") 45 — 45 — 75 — 75 — Other fixed-income securities 118 — 118 — 116 — 116 — Other investments measured at net asset value ("NAV") 189 — — — 188 — — — Restricted cash 103 103 — — 105 105 — — Long-term investments: Equity securities 263 263 — — 249 249 — — Enhanced equipment trust certificates ("EETC") 16 — — 16 18 — — 18 Avianca Holdings S.A. ("AVH") Derivative Assets 14 — — 14 11 — — 11
Carrying Values and Estimated Fair Values of Financial Instruments	The table below presents the carrying values and estimated fair values of financial instruments not presented in the tables above (in millions): March 31, 2019 December 31, 2018 Carrying Amount Fair Value Carrying Amount Fair Value Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Long-term debt $ 13,935 $ 14,136 $ — $ 10,307 $ 3,829 $ 13,445 $ 13,450 $ — $ 9,525 $ 3,925 Synergy Term Loan 480 422 — — 422 478 422 — — 422

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Components of Lease Cost	The Company's lease cost for the three months ended March 31 included the following components (in millions): 2019 2018 Operating lease cost $ 272 $ 326 Variable and short-term lease cost 606 611 Amortization of finance lease assets 18 23 Interest on finance lease liabilities 27 5 Sublease income (8 ) (10 ) Total lease cost $ 915 $ 955
Summary of Scheduled Future Minimum Lease Payments under Operating Leases	The table below summarizes the Company's scheduled future minimum lease payments under operating and finance leases, recorded on the balance sheet, as of March 31, 2019 (in millions): Operating Leases Finance Leases Last nine months of 2019 $ 662 $ 195 2020 985 96 2021 763 74 2022 630 47 2023 617 33 After 2023 4,252 69 Minimum lease payments 7,909 514 Imputed interest 2,125 145 Present value of minimum lease payments 5,784 369 Less: current maturities of lease obligations (639 ) (133 ) Long-term lease obligations $ 5,145 $ 236
Summary of Scheduled Future Minimum Lease Payments under Finance Leases	The table below summarizes the Company's scheduled future minimum lease payments under operating and finance leases, recorded on the balance sheet, as of March 31, 2019 (in millions): Operating Leases Finance Leases Last nine months of 2019 $ 662 $ 195 2020 985 96 2021 763 74 2022 630 47 2023 617 33 After 2023 4,252 69 Minimum lease payments 7,909 514 Imputed interest 2,125 145 Present value of minimum lease payments 5,784 369 Less: current maturities of lease obligations (639 ) (133 ) Long-term lease obligations $ 5,145 $ 236
Additional Information Related to Leases	The table below presents additional information related to our leases as of March 31 : 2019 2018 Weighted-average remaining lease term - finance leases 5 years 5 years Weighted-average remaining lease term - operating leases 10 years 10 years Weighted-average discount rate - finance leases 50.5 % (a) 6.7 % Weighted-average discount rate - operating leases 5.2 % 5.0 % (a) During the third quarter of 2018, United entered into an agreement with the lessor of 54 Embraer ERJ 145 aircraft to purchase those aircraft in 2019. The provisions of these lease agreements resulted in a change in accounting classification of these leases from operating leases to finance leases up until the purchase date. The discount rates used for these leases were adjusted so that the present value of lease payments did not exceed the fair value of the asset being recognized.
Supplemental Cash Flow Information Related to Leases	The table below presents supplemental cash flow information related to leases during the three months ended March 31 : 2019 2018 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 285 $ 279 Operating cash flows for finance leases 24 5 Financing cash flows for finance leases 20 18

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Firm Commitments and Options to Purchase Aircraft and Summary of Commitments	As of March 31, 2019 , United had firm commitments and options to purchase aircraft from The Boeing Company ("Boeing"), Airbus S.A.S. ("Airbus") and Embraer S.A. ("Embraer") presented in the table below: Aircraft Type Number of Firm Airbus A350 45 Boeing 737 MAX 171 Boeing 777-300ER 4 Boeing 787 20 Embraer E175 25 (a) United also has options and purchase rights for additional aircraft. The table below summarizes United's commitments as of March 31, 2019 , which include aircraft and related spare engines, aircraft improvements and all non-aircraft capital commitments: (in billions) Last nine months of 2019 $ 2.5 2020 5.4 2021 3.7 2022 3.1 2023 2.0 After 2023 7.0 $ 23.7

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Details of Pass Through Trusts	Certain details of the pass-through trusts with proceeds received from issuance of debt in 2019 are as follows (in millions, except stated interest rate): EETC Date Class Principal Final expected distribution date Stated interest rate Total debt recorded Proceeds received from issuance of debt during 2019 Remaining proceeds from issuance of debt to be received in future periods February 2019 AA $ 717 August 2031 4.15% $ 522 $ 522 $ 195 February 2019 A 296 August 2031 4.55% 216 216 80 $ 1,013 $ 738 $ 738 $ 275
Contractual Principal Payments under Long-Term Debt Agreements	The table below presents the Company's contractual principal payments (not including debt discount or debt issuance costs) at March 31, 2019 under then-outstanding long-term debt agreements (in millions): Last nine months of 2019 $ 979 2020 1,344 2021 1,338 2022 1,690 2023 740 After 2023 8,033 $ 14,124

Special Charges and Mark-to-M_2

Special Charges and Mark-to-Market ("MTM") Adjustments (Tables)	3 Months Ended
	Mar. 31, 2019
Other Income and Expenses [Abstract]
Components of Special Charges	For the three months ended March 31, special charges and MTM adjustments consisted of the following (in millions): Three Months Ended Operating: 2019 2018 Impairment of assets $ 8 $ 23 Severance and benefit costs 6 14 (Gains) losses on sale of assets and other special charges 4 3 Total operating special charges 18 40 Nonoperating MTM gains on financial instruments (17 ) (45 ) Total special charges and MTM gains on financial instruments 1 (5 ) Income tax expense — 1 Total special charges and MTM gains on financial instruments, net of income tax $ 1 $ (4 )

Recently Issued Accounting St_4

Recently Issued Accounting Standards - Impact of the Adoption of the New Lease Standard on the Statement of Consolidated Operations (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Regional capacity purchase	$ 688	$ 630	[1]
Landing fees and other rent	588	579	[1]
Depreciation and amortization	547	524	[1]
Interest expense	(188)	(162)	[1]
Interest capitalized	22	18	[1]
Net income	$ 292	$ 145	[1],[2],[3]
Earnings per share, basic and diluted (in dollars per share)	$ 1.09	$ 0.51	[1]
As Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Regional capacity purchase		$ 619
Landing fees and other rent		558
Depreciation and amortization		541
Interest expense		(176)
Interest capitalized		19
Net income		$ 147
Earnings per share, basic and diluted (in dollars per share)		$ 0.52
New Lease Standard | Adjustments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Regional capacity purchase		$ 11
Landing fees and other rent		21
Depreciation and amortization		(17)
Interest expense		14
Interest capitalized		(1)
Net income		$ (2)
Earnings per share, basic and diluted (in dollars per share)		$ (0.01)
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

Recently Issued Accounting St_5

Recently Issued Accounting Standards - Impact of the Adoption of the New Lease Standard on the Balance Sheet (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables, less allowance for doubtful accounts	$ 1,789	$ 1,426	[1]
Prepaid expenses and other	780	733	[1]
Flight equipment, owned and finance leases	33,705	32,599	[1]
Other property and equipment, owned and finance leases	7,165	6,889	[1]
Operating lease right-of-use assets	5,065	5,262	[1]
Current maturities of finance leases	133	123	[1]
Current maturities of operating leases	639	719	[1]
Other current liabilities	601	553	[1]
Long-term obligations under finance leases	236	224	[1]
Long-term obligations under operating leases	5,145	5,276	[1]
Deferred income taxes	898	828	[1]
Other long-term liabilities	998	1,010	[1]
Retained earnings	$ 6,999	6,715	[1]
As Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables, less allowance for doubtful accounts		1,346
Prepaid expenses and other		913
Flight equipment, owned and finance leases		32,636
Other property and equipment, owned and finance leases		7,930
Less-Accumulated depreciation and amortization, owned and finance leases		(13,414)
Operating lease right-of-use assets		0
Current maturities of finance leases		149
Current maturities of operating leases		0
Other current liabilities		619
Long-term obligations under finance leases		1,134
Long-term obligations under operating leases		0
Deferred income taxes		814
Other long-term liabilities		1,832
Retained earnings		6,668
New Lease Standard | Adjustments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables, less allowance for doubtful accounts		80
Prepaid expenses and other		(180)
Flight equipment, owned and finance leases		(37)
Other property and equipment, owned and finance leases		(1,041)
Less-Accumulated depreciation and amortization, owned and finance leases		148
Operating lease right-of-use assets		5,262
Current maturities of finance leases		(26)
Current maturities of operating leases		719
Other current liabilities		(66)
Long-term obligations under finance leases		(910)
Long-term obligations under operating leases		5,276
Deferred income taxes		14
Other long-term liabilities		(822)
Retained earnings		$ 47
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

Recently Issued Accounting St_6

Recently Issued Accounting Standards - Impact of the Adoption of the New Lease Standard on the Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash Flows from Operating Activities:
Net cash provided by operating activities	$ 1,915	$ 1,709	[1]
Cash Flows from Investing Activities:
Capital expenditures	(1,609)	(944)	[1]
Cash Flows from Financing Activities:
Proceeds from issuance of long-term debt	646	673	[1]
Principal payments under finance leases	$ (20)	(18)	[1]
As Reported
Cash Flows from Operating Activities:
Net cash provided by operating activities		1,733
Cash Flows from Investing Activities:
Capital expenditures		(979)
Cash Flows from Financing Activities:
Proceeds from issuance of long-term debt		696
Principal payments under finance leases		(30)
New Lease Standard | Adjustments
Cash Flows from Operating Activities:
Net cash provided by operating activities		(24)
Cash Flows from Investing Activities:
Capital expenditures		35
Cash Flows from Financing Activities:
Proceeds from issuance of long-term debt		(23)
Principal payments under finance leases		$ 12
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

Revenue - Revenue by Principal

Revenue - Revenue by Principal Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 9,589	$ 9,032	[1]
Domestic (U.S. and Canada)
Disaggregation of Revenue [Line Items]
Revenue	5,875	5,476
Atlantic
Disaggregation of Revenue [Line Items]
Revenue	1,458	1,389
Pacific
Disaggregation of Revenue [Line Items]
Revenue	1,281	1,231
Latin America
Disaggregation of Revenue [Line Items]
Revenue	$ 975	$ 936
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

Revenue - Narrative (Details)

Revenue - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue From Contract With Customer [Line Items]
Revenue	$ 9,589	$ 9,032	[1]
Passenger Revenue
Revenue From Contract With Customer [Line Items]
Ancillary fees	571	497
Revenue	8,725	8,149	[1]
Passenger Revenue | Deferred Revenue for Miles in Loyalty Program
Revenue From Contract With Customer [Line Items]
Revenue	2,700	2,500
Other Operating Revenue
Revenue From Contract With Customer [Line Items]
Revenue	578	590	[1]
Other Operating Revenue | Chase and Other Partner Agreements
Revenue From Contract With Customer [Line Items]
Revenue	$ 473	$ 494
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

Revenue - Roll Forward of Frequ

Revenue - Roll Forward of Frequent Flyer Deferred Revenue (Details) - Deferred Revenue for Miles in Loyalty Program - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Frequent Flyer Deferred Revenue [Roll Forward]
Total Frequent flyer deferred revenue - beginning balance	$ 5,005	$ 4,783
Miles awarded	607	603
Travel miles redeemed (Passenger revenue)	(438)	(409)
Non-travel miles redeemed (Other operating revenue)	(36)	(40)
Total Frequent flyer deferred revenue - ending balance	$ 5,138	$ 4,937

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings available to common stockholders	$ 292	$ 145
Basic weighted-average shares outstanding (in shares)	267	283.9
Effect of employee stock awards (in shares)	1.3	1
Diluted weighted-average shares outstanding (in shares)	268.3	284.9
Earnings per share, basic and diluted (in dollars per share)	$ 1.09	$ 0.51	[1]
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Loss Per Share [Line Items]
Repurchases of common stock	$ 527	$ 569
Open Market Repurchase Program
Earnings Loss Per Share [Line Items]
Number of shares repurchased (in shares)	6.3
Repurchases of common stock	$ 527
Amount remaining under repurchase programs	$ 1,200

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income, Net of Tax (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019		Mar. 31, 2018
Deferred Tax
Balance		$ (136)		$ (39)
Changes in value		(3)		(6)
Amounts reclassified to earnings		(1)		(3)
Amounts reclassified to retained earnings				0
Balance		(140)		(48)
Net of Tax
Balance	[2]	10,042	[1]	8,788
Changes in value		7		13
Amounts reclassified to earnings		3		13
Amounts reclassified to retained earnings				7
Balance		9,802		8,388	[2]
Pension and Other Postretirement Liabilities
Before Tax
Balance		(663)		(1,102)
Changes in value		5		23
Amounts reclassified to earnings		4		16
Amounts reclassified to retained earnings				0
Balance		(654)		(1,063)
Investments and Other
Before Tax
Balance		(4)		(6)
Changes in value		5		(4)
Amounts reclassified to earnings		0		0
Amounts reclassified to retained earnings				7
Balance		1		(3)
Accumulated Other Comprehensive Income (Loss)
Net of Tax
Balance	[2]	(803)		(1,147)
Balance		$ (793)		$ (1,114)	[2]
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Effective income tax rate	20.40%	20.30%

Employee Benefit Plans - Compon

Employee Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 46	$ 57
Interest cost	57	54
Expected return on plan assets	(72)	(73)
Amortization of unrecognized (gain) loss	29	33
Amortization of prior service credit	0	0
Total	60	71
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	3
Interest cost	15	15
Expected return on plan assets	0	0
Amortization of unrecognized (gain) loss	(15)	(8)
Amortization of prior service credit	(10)	(9)
Total	$ (8)	$ 1

Employee Benefit Plans - Narrat

Employee Benefit Plans - Narrative (Details) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)shares
Compensation and Retirement Disclosure [Abstract]
Number of days used to compute performance period average closing price of restricted stock units	20 days
RSUs
Compensation and Retirement Disclosure [Abstract]
Awards granted (in shares) | shares	0.5
Vesting period	3 years
Pension Benefits
Compensation and Retirement Disclosure [Abstract]
Employer contribution to tax-qualified defined benefit pension plans | $	$ 150

Employee Benefit Plans - Inform

Employee Benefit Plans - Information Related to Share-Based Compensation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Employee-related Liabilities [Abstract]
Share-based compensation expense	$ 16	$ 17
Unrecognized share-based compensation	$ 84		$ 68

Financial Instruments and Fai_3

Financial Instruments and Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Measured on a Recurring Basis - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 1,848	$ 1,694
Restricted cash	103	105
Equity securities	263	249
Enhanced equipment trust certificates (EETC)	16	18
Avianca Holdings S.A. (AVH) Derivative Assets	14	11
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	1,848	1,694
Restricted cash	103	105
Equity securities	263	249
Enhanced equipment trust certificates (EETC)	0	0
Avianca Holdings S.A. (AVH) Derivative Assets	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Restricted cash	0	0
Equity securities	0	0
Enhanced equipment trust certificates (EETC)	0	0
Avianca Holdings S.A. (AVH) Derivative Assets	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Restricted cash	0	0
Equity securities	0	0
Enhanced equipment trust certificates (EETC)	16	18
Avianca Holdings S.A. (AVH) Derivative Assets	14	11
Corporate debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	1,014	1,023
Corporate debt | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Corporate debt | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	1,014	1,023
Corporate debt | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	745	746
Asset-backed securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Asset-backed securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	745	746
Asset-backed securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
U.S. government and agency notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	108	108
U.S. government and agency notes | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
U.S. government and agency notes | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	108	108
U.S. government and agency notes | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Certificates of deposit placed through an account registry service (CDARS)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	45	75
Certificates of deposit placed through an account registry service (CDARS) | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Certificates of deposit placed through an account registry service (CDARS) | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	45	75
Certificates of deposit placed through an account registry service (CDARS) | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Other fixed-income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	118	116
Other fixed-income securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Other fixed-income securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	118	116
Other fixed-income securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Other investments measured at net asset value (NAV)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	189	188
Other investments measured at net asset value (NAV) | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Other investments measured at net asset value (NAV) | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Other investments measured at net asset value (NAV) | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 0	$ 0

Financial Instruments and Fai_4

Financial Instruments and Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Nov. 30, 2018	Apr. 30, 2018
Synergy
Fair Value [Line Items]
Loan amount		$ 456
Number of shares pledged as loan collateral (in shares)		516,000,000
Azul
Fair Value [Line Items]
Equity stake			2.00%
Azul | Preferred Stock
Fair Value [Line Items]
Equity stake			8.00%
Asset-Backed Securities | Minimum
Fair Value [Line Items]
Available-for-sale securities remaining maturities	1 year
Asset-Backed Securities | Maximum
Fair Value [Line Items]
Available-for-sale securities remaining maturities	16 years
Corporate Debt | Minimum
Fair Value [Line Items]
Available-for-sale securities remaining maturities	1 year
Corporate Debt | Maximum
Fair Value [Line Items]
Available-for-sale securities remaining maturities	3 years
CDARS | Maximum
Fair Value [Line Items]
Available-for-sale securities remaining maturities	1 year
U.S. Government and Other Securities | Minimum
Fair Value [Line Items]
Available-for-sale securities remaining maturities	1 year
Other Fixed-Income Securities | Maximum
Fair Value [Line Items]
Available-for-sale securities remaining maturities	2 years

Financial Instruments and Fai_5

Financial Instruments and Fair Value Measurements - Carrying Values and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 13,935	$ 13,445
Synergy Term Loan	480	478
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	14,136	13,450
Synergy Term Loan	422	422
Level 1 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	0	0
Synergy Term Loan	0	0
Level 2 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	10,307	9,525
Synergy Term Loan	0	0
Level 3 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	3,829	3,925
Synergy Term Loan	$ 422	$ 422

Leases - Components of Lease Co

Leases - Components of Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Leases [Abstract]
Operating lease cost	$ 272	$ 326
Variable and short-term lease cost	606	611
Amortization of finance lease assets	18	23
Interest on finance lease liabilities	27	5
Sublease income	(8)	(10)
Total lease cost	$ 915	$ 955

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)aircraft
Lessee, Lease, Description [Line Items]
Additional leases that have not yet commenced | $	$ 140
Maximum
Lessee, Lease, Description [Line Items]
Lease terms of additional leases that have not yet commenced (up to)	34 years
Mainline Aircraft
Lessee, Lease, Description [Line Items]
Number of aircraft subject to operating leases	122
Number of aircraft subject to finance leases	30
Mainline Aircraft | Minimum
Lessee, Lease, Description [Line Items]
Initial term of operating leases	2 months
Mainline Aircraft | Maximum
Lessee, Lease, Description [Line Items]
Initial term of operating leases	10 years
Regional Aircraft
Lessee, Lease, Description [Line Items]
Number of aircraft subject to operating leases	341
Number of aircraft subject to finance leases	76
Non-Aircraft | Minimum
Lessee, Lease, Description [Line Items]
Initial term of operating leases	1 month
Non-Aircraft | Maximum
Lessee, Lease, Description [Line Items]
Initial term of operating leases	34 years

Leases - Summary of Scheduled F

Leases - Summary of Scheduled Future Minimum Lease Payments under Operating and Finance Leases (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018	[1]
Operating Leases
Last nine months of 2019	$ 662
2020	985
2021	763
2022	630
2023	617
After 2023	4,252
Minimum lease payments	7,909
Imputed interest	2,125
Present value of minimum lease payments	5,784
Less: current maturities of lease obligations	(639)	$ (719)
Long-term lease obligations	5,145	5,276
Finance Leases
Last nine months of 2019	195
2020	96
2021	74
2022	47
2023	33
After 2023	69
Minimum lease payments	514
Imputed interest	145
Present value of minimum lease payments	369
Less: current maturities of lease obligations	(133)	(123)
Long-term lease obligations	$ 236	$ 224
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

Leases - Additional Information

Leases - Additional Information Related to Leases (Details) - aircraft	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2018
Lessee, Lease, Description [Line Items]
Weighted-average remaining lease term - finance leases	5 years	5 years
Weighted-average remaining lease term - operating leases	10 years	10 years
Weighted-average discount rate - finance leases	50.50%	6.70%
Weighted-average discount rate - operating leases	5.20%	5.00%
Embraer ERJ 145
Lessee, Lease, Description [Line Items]
Number of leased aircraft			54

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$ 285	$ 279
Operating cash flows for finance leases	24	5
Financing cash flows for finance leases	$ 20	$ 18	[1]
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

Commitments and Contingencies -

Commitments and Contingencies - Firm Commitments and Options to Purchase Aircraft (Details)	Mar. 31, 2019commitment
Airbus A350
Long-term Purchase Commitment [Line Items]
Number of firm commitments	45
Boeing 737 MAX
Long-term Purchase Commitment [Line Items]
Number of firm commitments	171
Boeing 777-300ER
Long-term Purchase Commitment [Line Items]
Number of firm commitments	4
Boeing 787
Long-term Purchase Commitment [Line Items]
Number of firm commitments	20
Embraer E175
Long-term Purchase Commitment [Line Items]
Number of firm commitments	25

Commitments and Contingencies_2

Commitments and Contingencies - Narrative (Details) $ / shares in Units, employee in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)aircraftemployeecommitment	Dec. 31, 2019aircraft	Mar. 13, 2019aircraft	Mar. 12, 2019aircraft	Nov. 30, 2018USD ($)$ / sharesshares	Sep. 30, 2018aircraft
Commitments and Contingencies [Line Items]
Remaining term of debt	12 years
United Airlines, Inc.
Commitments and Contingencies [Line Items]
Number of employees | employee	93
Percentage of employees represented by various U.S. labor organizations	84.00%
Kingsland
Commitments and Contingencies [Line Items]
Number of shares that may be put to United (in shares) | shares					144,800,000
Number of ADRs that may be put into United (in shares) | shares					18,100,000
Market price of common stock at fifth anniversary (in dollars per share) | $ / shares					$ 12
Aggregate maximum possible combined put payment and guarantee amount | $					$ 217
Liability for the fair value of guarantees | $					$ 31
Tax-Exempt Special Facilities Revenue Bonds
Commitments and Contingencies [Line Items]
Aggregate principal amount of guarantee | $	$ 1,900
Floating Rate Debt
Commitments and Contingencies [Line Items]
Debt | $	3,400
Fixed Rate Debt
Commitments and Contingencies [Line Items]
Debt | $	$ 18
Loans and Leases from Non-U.S. Entities
Commitments and Contingencies [Line Items]
Remaining term of debt	12 years
Aggregate balance | $	$ 3,200
Aircraft Mortgage Debt
Commitments and Contingencies [Line Items]
Aggregate principal amount of guarantee | $	$ 142
Embraer E175
Commitments and Contingencies [Line Items]
Number of aircraft expected to take delivery of in 2019	25
Number of aircraft committed to purchase | commitment	25
Boeing 737 MAX
Commitments and Contingencies [Line Items]
Number of aircraft expected to take delivery of in 2019	16
Number of aircraft expected to take delivery of in 2020	28
Number of aircraft committed to purchase | commitment	171
Number of aircraft grounded under emergency order			14
Number of flights operated using grounded aircraft				50
Boeing 737 MAX | Forecast
Commitments and Contingencies [Line Items]
Number of expected flights operating per day prior to grounding order		110
Boeing 787
Commitments and Contingencies [Line Items]
Number of aircraft expected to take delivery of in 2019	4
Number of aircraft expected to take delivery of in 2020	15
Number of aircraft committed to purchase | commitment	20
Boeing 777-300ER
Commitments and Contingencies [Line Items]
Number of aircraft expected to take delivery of in 2019	2
Number of aircraft expected to take delivery of in 2020	2
Airbus A319
Commitments and Contingencies [Line Items]
Number of aircraft committed to purchase	20
Embraer ERJ 145
Commitments and Contingencies [Line Items]
Number of leased aircraft						54

Commitments and Contingencies_3

Commitments and Contingencies - Summary of Commitments (Details) $ in Billions	Mar. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
Last nine months of 2019	$ 2.5
2020	5.4
2021	3.7
2022	3.1
2023	2
After 2023	7
Total commitments	$ 23.7

Debt - Narrative (Details)

Debt - Narrative (Details)	1 Months Ended
	Feb. 28, 2019trust	Mar. 31, 2019USD ($)
Debt Instrument [Line Items]
Number of pass-through trusts created | trust	2
Revolving Credit Facility | United Airlines, Inc. | Secured Debt
Debt Instrument [Line Items]
Available under revolving credit facility | $		$ 2,000,000,000

Debt - Details of Pass Through

Debt - Details of Pass Through Trusts (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Debt Instrument [Line Items]
Proceeds received from issuance of debt	$ 646,000,000	$ 673,000,000	[1]
United Airlines, Inc.
Debt Instrument [Line Items]
Proceeds received from issuance of debt	646,000,000	$ 673,000,000	[2]
United Airlines, Inc. | Class AA Pass Through Certificates | February 2019
Debt Instrument [Line Items]
Principal	$ 717,000,000
Stated interest rate	4.15%
Total debt recorded	$ 522,000,000
Proceeds received from issuance of debt	522,000,000
Remaining proceeds from issuance of debt to be received in future periods	195,000,000
United Airlines, Inc. | Class A Pass Through Certificates | February 2019
Debt Instrument [Line Items]
Principal	$ 296,000,000
Stated interest rate	4.55%
Total debt recorded	$ 216,000,000
Proceeds received from issuance of debt	216,000,000
Remaining proceeds from issuance of debt to be received in future periods	80,000,000
United Airlines, Inc. | ETTC
Debt Instrument [Line Items]
Principal	1,013,000,000
Total debt recorded	738,000,000
Proceeds received from issuance of debt	738,000,000
Remaining proceeds from issuance of debt to be received in future periods	$ 275,000,000
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

Debt - Contractual Principal Pa

Debt - Contractual Principal Payments (Details) - UAL And United $ in Millions	Mar. 31, 2019USD ($)
Debt Instrument [Line Items]
Last nine months of 2019	$ 979
2020	1,344
2021	1,338
2022	1,690
2023	740
After 2023	8,033
Long-term debt	$ 14,124

Special Charges and Mark-to-M_3

Special Charges and Mark-to-Market ("MTM") Adjustments - Components of Special Charges (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating:
Impairment of assets	$ 8	$ 23
Severance and benefit costs	6	14
(Gains) losses on sale of assets and other special charges	4	3
Total operating special charges	18	40	[1]
Nonoperating MTM gains on financial instruments	(17)	(45)
Total special charges and MTM gains on financial instruments	1	(5)
Income tax expense	0	1
Total special charges and MTM gains on financial instruments, net of income tax	$ 1	$ (4)
[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2016-02, Leases (Topic 842). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

Special Charges and Mark-to-M_4

Special Charges and Mark-to-Market ("MTM") Adjustments - Narrative (Details) Employee in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)Employee
Restructuring Cost and Reserve [Line Items]
Fair value adjustment for aircraft purchased off lease and impairments related to certain fleet types and certain international slots no longer in use	$ 8,000,000	$ 23,000,000
Severance and benefit costs	6,000,000	14,000,000
Gain for the change in fair value of certain derivative assets	3,000,000
Azul
Restructuring Cost and Reserve [Line Items]
Gain (loss) for the change in fair value of equity investments	14,000,000	45,000,000
Management
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs	4,000,000	6,000,000
International Brotherhood of Teamsters | Voluntary Early-Out Program
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs	$ 2,000,000	$ 8,000,000
Number of technicians and related employees electing to voluntarily separate from the Company | Employee			1
Severance payment per participant (up to)			$ 100,000

Uncategorized Items - ual-20190

Label	Element	Value
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (7,000,000)
AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 7,000,000