Notes Receivable (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012 Contract	Sep. 30, 2011	Sep. 30, 2012 Contract	Sep. 30, 2011
Supplemental Cash Flow Information [Line Items]
Number of notes receivable	2		2
Interest Income	$ 3.1	$ 3.2	$ 9.2	$ 9.5
Payment received relating to notes receivables			$ 15.5	$ 14.4

The cash inflow associated with the collection, including prepayments, of loans receivable issued for financing of goods and services.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 15, 16

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3179-108585

Name:	us-gaap_ProceedsFromCollectionOfLoansReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration