Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Receivables, allowance for doubtful accounts	$ 8	$ 7
Aircraft fuel, spare parts and supplies, obsolescence allowance	96	89
Intangibles, accumulated amortization	701	670
Common stock, par value	$ 0.01	$ 0.01
Common shares, authorized	1,000,000,000	1,000,000,000
Common shares, outstanding	332,043,357	330,906,192
United Airlines Inc [Member]
Receivables, allowance for doubtful accounts	5	5
Aircraft fuel, spare parts and supplies, obsolescence allowance	75	73
Intangibles, accumulated amortization	547	534
Common stock, par value	$ 5	$ 5
Common shares, authorized	1,000	1,000
Common shares, outstanding	205	205
Continental Airlines Inc [Member]
Receivables, allowance for doubtful accounts	3	2
Aircraft fuel, spare parts and supplies, obsolescence allowance	21	16
Intangibles, accumulated amortization	$ 154	$ 136
Common stock, par value	$ 0.01	$ 0.01
Common shares, authorized	1,000	1,000
Common shares, outstanding	1,000	1,000