Fair Value Measurement - Carrying and Fair Value Amounts (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Senior Notes	$ 208.3	$ 216.7	$ 216.7
Cost-method Investments, Other than Temporary Impairment	$ 2.8

- Definition

This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the cost method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment.

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