Fair Value Measurements - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2012	Dec. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Series A preferred stock, par value	$ 0.01	$ 0.01	$ 0.01
Liability for the Change of Control	$ 0.2	$ 0.2
Estimated fair value of long term debt and Preferred Stock	1,243.3	1,243.3	1,240.6
Carrying value of debt, including current portion of debt, and preferred stock	$ 1,217.1	$ 1,217.1	$ 1,221.8

- Definition

Face amount or stated value per share of stock classified as temporary equity; generally not indicative of the fair market value per share. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

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