Derivative Financial Instruments Derivative Instruments Designated as Cash Flow Hedges OCI Activity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Derivatives [Line Items]
Net unrealized gain on qualifying cash flow hedges, net of tax	$ 4,437	$ 446
Designated as Hedging Instrument [Member] \| Interest rate swap agreements [Member]
Derivatives [Line Items]
Net unrealized gain on qualifying cash flow hedges, net of tax	$ 4,437	$ 446

Net of tax and reclassification adjustments amount of the change in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Also includes an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

Name:	us-gaap_OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration