Stock-Based Compensation (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Stock compensation expense	$ 2.7	$ 2.8	$ 7.7	$ 8.3
Capitalized stock compensation cost	0.6	0.7	1.9	2.0
Tax benefit related to stock based compensation	1.1	1.1	3.0	3.2
Unrecognized compensation cost related to unvested awards	11.2		11.2
Unrecognized compensation cost, expect to be capitalized	2.2		2.2
Weighted average years over which this cost will be recognized			0.8
SARs, shares granted	0	0	0	0
Increase in stock compensation expense due to the stock options granted	0.4		0.6
Increase in stock compensation expense due to the restricted stock awards granted			$ 3.5
Minimum [Member] \| First Half Of 2014 [Member]
Performance percentage criteria			50.00%
Maximum [Member] \| First Half Of 2014 [Member]
Performance percentage criteria			150.00%
First Half Of 2014 [Member]
Restricted stock awards granted to designated executive officers			20,062
Restricted stock awards to be vested			30.00%

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Increase In Stock Compensation Expense Due To The Restricted Stock Awards Granted

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Performance Percentage Criteria

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Restricted Stock Awards Granted To Vested In Period if performance criteria are met.

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Represents the compensation cost capitalized during the period arising from equity-based compensation arrangements (for example, shares of stock, units, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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The weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, using a decimal to express in number of years.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Equity-based compensation cost during the period with respect to the award, which will be recognized in income (as well as the total recognized tax benefit) or capitalized as part of the cost of an asset.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards.

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