Accounts and Notes Receivable and Allowance for Credit Losses - Additional Information (Detail) (USD $)			9 Months Ended
Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Future Period
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross lease receivables	$ 344,299,000	$ 335,500,000
Sales of leases to third parties without recourse			$ 54,800,000

Amount of minimum lease payments to be received by the lessor for capital leases.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6952072&loc=d3e45377-112738

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 23

-Subparagraph a(i)(a)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_CapitalLeasesFutureMinimumPaymentsReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant