Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	[1]
Receivables, allowance for doubtful accounts	$ 7	$ 7
Aircraft fuel, spare parts and supplies, obsolescence allowance	365	354
Intangibles, accumulated amortization	$ 1,329	$ 1,313
Common stock, par value	$ 0.01	$ 0.01
Common shares, authorized	1,000,000,000	1,000,000,000
Common shares, outstanding	279,410,451	286,973,195
United Airlines, Inc.
Receivables, allowance for doubtful accounts	$ 7	$ 7
Aircraft fuel, spare parts and supplies, obsolescence allowance	365	354
Intangibles, accumulated amortization	$ 1,329	$ 1,313
Common stock, par value	$ 0.01	$ 0.01
Common shares, authorized	1,000	1,000
Common shares, issued	1,000	1,000
Common shares, outstanding	1,000	1,000

[1] Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.