Stock-Based Compensation And Directors Stock Purchase Plan (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011 years	Dec. 31, 2010	Dec. 31, 2009
Stock-based compensation expense	$ 4.7	$ 6.0	$ 6.6
Total tax benefit recognized from compensation arrangements	1.8	2.2	2.5
Fair value of shares vested during the period	1.6	2.1	1.7
Unrecognized compensation cost related to unvested options, SARs and stock awards	$ 12.3
Remaining number of shares available for issuance under the plan	3,119,281
Number of shares purchased under stock option plan	19,135	21,184
Average price of share purchased under stock option plan	$ 38.67	$ 35.27
Common stock dividend rate percentage	5.00%
Compensation cost is expected to be recognized over a weighted average period, years	4.1
Stock Options [Member]
Contractual term, years	10
2011 Stock Awards [Member]
Stock awards vesting period, minimum	5
Stocks awards vesting period, maximum	7
2006 Stock Awards [Member]
Stock awards vesting period	4
2005 Stock Award [Member]
Stock awards vesting period	3
Stock Appreciation Rights (SARs) [Member]
Contractual term, years	10
Directors Stock Purchase Plan [Member]
Remaining number of shares available for issuance under the plan	48,355

Common stock dividend rate percentage.

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Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period Contractual Terms

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, 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 total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Description of the period of time over which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, which may be expressed in a variety of ways (for example, in years, month and year).

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The total fair value of equity-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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The weighted-average period between the balance sheet date and expiration date for fully vested and expected to vest options that are exercisable (or convertible) under the plan, which may be expressed in a decimal value for number of years.

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The weighted average of per share prices paid for shares purchased on the open market for issuance to employees under the plan.

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The number of shares purchased on the open market during the period for issuance to employees under the plan.

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