Derivative Financial Instruments Derivative Instruments Designated as Cash Flow Hedges OCI Activity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivatives [Line Items]
Effective portion of changes in fair value recognized in OCI	$ 12,274	$ 617	$ 16,712	$ 1,063
Designated as Hedging Instrument [Member] \| Interest rate swap agreements [Member]
Derivatives [Line Items]
Effective portion of changes in fair value recognized in OCI	$ 12,274	$ 617	$ 16,712	$ 1,063

Amount after tax and reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and 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=28358780&loc=SL7669646-108580

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration