Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Receivables - allowance for credit losses	$ 71	$ 78
Aircraft fuel, spare, parts and supplies - obsolescence allowance	518	478
Intangibles - accumulated amortization	1,519	1,495
Investments in affiliates and other - allowance for credit losses	$ 606	$ 522
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)	323,610,765	311,845,232
United Airlines, Inc.
Receivables - allowance for credit losses	$ 71	$ 78
Aircraft fuel, spare, parts and supplies - obsolescence allowance	518	478
Intangibles - accumulated amortization	1,519	1,495
Investments in affiliates and other - allowance for credit losses	$ 606	$ 522
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