Financial Instruments (Details 2) (USD $) In Millions, unless otherwise specified	9 Months Ended		9 Months Ended
Sep. 30, 2011 Interest Rate Swaps One [Member]	Sep. 30, 2011 Interest Rate Swaps Two [Member]	Mar. 31, 2011 Interest Rate Swaps Two [Member]	Sep. 30, 2011 Interest Rate Swaps Three [Member]	Jun. 30, 2011 Interest Rate Swaps Three [Member]
Information regarding the Swaps
Aggregate Notional Amount	$ 100.0	$ 84.4	$ 85.0	$ 100.0	$ 100.0
LIBOR Fixed Rate	4.80%	2.80%		1.00%
Maturity date	Feb. 28, 2012	Sep. 30, 2017		Jun. 30, 2014

Aggregate notional amount of all interest rate derivatives designated as hedging instruments in cash flow hedges. Notional amount refers to the monetary amount specified in the interest rate derivative contract.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5580258-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5579245-113959

Name:	us-gaap_NotionalAmountOfInterestRateCashFlowHedgeDerivatives
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant