Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Receivables, allowance for doubtful accounts	$ 21	$ 13
Aircraft fuel, spare parts and supplies, obsolescence allowance	145	125
Intangibles, accumulated amortization	864	792
Common stock, par value	$ 0.01	$ 0.01
Common shares, authorized	1,000,000,000	1,000,000,000
Common shares, outstanding	355,889,762	332,472,779
United Airlines, Inc.
Receivables, allowance for doubtful accounts	21	13
Aircraft fuel, spare parts and supplies, obsolescence allowance	145	125
Intangibles, accumulated amortization	$ 864	$ 792
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