Summary of Fair Value of Interest Rate Swaps (Details) (Interest Rate Swap, Other Noncurrent Liabilities, USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Interest Rate Swap \| Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Fair value	$ (3,338)	$ (3,216)

Fair value as of the balance sheet date of all interest rate derivative liabilities designated as cash flow hedging instruments.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (c)(1)

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

Name:	us-gaap_InterestRateCashFlowHedgeLiabilityAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant