Supplemental Disclosures to the Statements of Cash Flows (Details Textual) (USD $)	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010
Supplemental Disclosures to the Statements of Cash Flows (Textual) [Abstract]
Unpaid change in liabilities for investing activities	$ 18,658,000	$ 5,512,000
Unpaid capital expenditures	$ 26,657,000	$ 10,761,000

The increase (decrease) in noncurrent deferred charges, classified as investing activities.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 13

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3213-108585

Name:	us-gaap_IncreaseDecreaseInDeferredChargesInvesting
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration