Accounts and Notes Receivable and Allowance for Credit Losses - Additional Information (Detail) (Future Period, USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011
Future Period
Financing Receivable, Recorded Investment, Past Due [Line Items]
Sales of leases to third parties without recourse	$ 92.3

Total amount of lease revenue realized in the period on leasing arrangements.

No definition available.

Name:	us-gaap_CapitalLeasesIncomeStatementLeaseRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration