Interest rate stated in the contractual debt agreement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 22
-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Supplemental Guarantor Information (Details)	6 Months Ended
Supplemental Guarantor Information (Details)	Jun. 30, 2011	Jun. 30, 2011 6.9 percent senior notes due June 2013	Dec. 31, 2010 6.9 percent senior notes due June 2013	Jun. 30, 2011 5.4 percent senior notes due January 2015	Dec. 31, 2010 5.4 percent senior notes due January 2015	Jun. 30, 2011 8.4 percent senior notes due May 2017	Dec. 31, 2010 8.4 percent senior notes due May 2017	Jun. 30, 2011 6.6 percent senior notes due May 2020	Dec. 31, 2010 6.6 percent senior notes due May 2020
Supplemental Guarantor Information
Percentage ownership of Guarantor Subsidiaries (as a percent)	100.00%
Interest rate on obligations of the parent, guaranteed by the Guarantor Subsidiaries
Interest rate stated percentage (as a percent)		6.90%	6.90%	5.40%	5.40%	8.40%	8.40%	6.60%	6.60%