Accounts and Notes Receivable and Allowance for Credit Losses - Additional Information (Detail) (USD $)			6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Future Period
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross lease receivables	$ 328,582,000	$ 272,300,000
Sales of leases to third parties without recourse			$ 35,000,000

Future minimum lease rental payments receivable for the five years following the balance sheet date and the future minimum payment amount in total on nonoperating leases (direct financing, sales-type and leveraged leases).

Reference 1: 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 2: 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

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