Financial Guarantees (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Guarantor Obligations [Line Items]
Maximum potential payment	$ 139.9
Guarantee Liability Carrying Amount	12.8
Guarantees on the residual values of leased properties
Guarantor Obligations [Line Items]
Guarantee Obligations Term	One to four years
Maximum potential payment	31.6
Guarantee Liability Carrying Amount	4.4
Guarantee on the residual value of aircraft
Guarantor Obligations [Line Items]
Guarantee Obligations Term	Less than nine years
Maximum potential payment	24.2
Standby letters of credit
Guarantor Obligations [Line Items]
Guarantee Obligations Term	Up to three years
Maximum potential payment	66.5
Commercial customer financing arrangements
Guarantor Obligations [Line Items]
Guarantee Obligations Term	Up to six years
Maximum potential payment	17.6
Guarantee Liability Carrying Amount	$ 12.8