Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Receivables, allowance for doubtful accounts	$ 22	$ 13
Aircraft fuel, spare parts and supplies, obsolescence allowance	169	162
Intangibles, accumulated amortization	1,049	933
Common stock, par value	$ 0.01	$ 0.01
Common shares, authorized	1,000,000,000	1,000,000,000
Common shares, outstanding	374,525,916	362,283,555
United Airlines, Inc.
Receivables, allowance for doubtful accounts	22	13
Aircraft fuel, spare parts and supplies, obsolescence allowance	169	162
Intangibles, accumulated amortization	$ 1,049	$ 933
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