Discontinued Operations - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended
Jan. 27, 2011	Dec. 31, 2010	Jan. 20, 2010	Sep. 30, 2011	Sep. 30, 2010
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash provided by investing activities of discontinued operations	$ 25,500,000		$ 42,646,000	$ 25,500,000	$ 42,646,000
Impairment of the assets to be disposed		$ 2,200,000

This element represents cash provided by or used in the investing activities of the entity's discontinued operations during the period. This element is only used by those entities that separately report cash flows attributable to discontinued operations. If using this element, it is an indication that the cash flows of the entity which are detailed in reconciling to cash provided by or used in investing activities reflect only cash flows attributable to continuing operations.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 26

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 230

-SubTopic 10

-Section 45

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3521-108585

Name:	us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration