Long-term Debt and Derivatives (Details 5) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Derivatives instruments impact on consolidated balance sheets
Fair value of derivative liabilities	$ 1,437	$ 16,746
Derivatives Designated as Hedging Instruments
Derivatives instruments impact on consolidated balance sheets
Fair value of derivative liabilities		13,034
Derivatives Designated as Hedging Instruments \| Interest rate swap contracts
Derivatives instruments impact on consolidated balance sheets
Fair value of derivative liabilities		13,034
Derivatives Not Designated as Hedging Instruments
Derivatives instruments impact on consolidated balance sheets
Fair value of derivative liabilities	1,437	3,712
Derivatives Not Designated as Hedging Instruments \| Interest rate swap contracts
Derivatives instruments impact on consolidated balance sheets
Fair value of derivative liabilities	$ 1,437	$ 3,712

Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624163-113959

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44C

-Subparagraph a

-Clause 1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 205G

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

Name:	us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant