Supplemental Balance Sheet Information (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Other assets
Rabbi trust assets, including cash surrender value of life insurance contracts	$ 116.1	$ 115.1
Investments in affiliated companies	26.4	17.8
Foreign currency hedges	19.3	43.9
All other	66.4	79.1
Total	671.3	624.6
Rotable Asset [Member]
Other assets
Other Deferred Costs, Net	136.3	130.3
Participation Payments [Member]
Other assets
Other Deferred Costs, Net	175.8	116.7
Sales Incentives [Member]
Other assets
Other Deferred Costs, Net	62.7	55.6
Flight Certification Costs [Member]
Other assets
Other Deferred Costs, Net	47.0	42.8
Entry Fees [Member]
Other assets
Other Deferred Costs, Net	$ 21.3	$ 23.3