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Derivative Instruments and Hedging Activities (Details) (Interest Rate Swap [Member], USD $)
In Millions, unless otherwise specified |
12 Months Ended | ||
|---|---|---|---|
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Dec. 31, 2011
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Dec. 31, 2010
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Dec. 31, 2009
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Interest Rate Swap [Member]
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| Aggregate Interest Rate Swaps and Fair Value of Liabilities Outstanding [Abstract] | |||
| Aggregate Notional Amounts | $ 140.0 | $ 140.0 | |
| Average Swap Rate | 2.78% | 2.78% | 2.78% |
| Aggregate Fair Value | $ (5.1) | $ (6.6) | |
| Maturity dates | Jun. 01, 2013 | Jun. 01, 2013 | Jul. 01, 2013 |