Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Receivables, allowance for doubtful accounts	$ 16	$ 13
Aircraft fuel, spare parts and supplies, obsolescence allowance	157	125
Intangibles, accumulated amortization	900	792
Common stock, par value	$ 0.01	$ 0.01
Common shares, authorized	1,000,000,000	1,000,000,000
Common shares, outstanding	361,871,040	332,472,779
United Airlines, Inc.
Receivables, allowance for doubtful accounts	16	13
Aircraft fuel, spare parts and supplies, obsolescence allowance	157	125
Intangibles, accumulated amortization	$ 900	$ 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