Description of the period of time over which director's right to exercise an award is no longer contingent on the 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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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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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 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).

+ References

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The weighted average fair value at grant date for nonvested equity-based awards issued 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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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This item represents the conversion ratio used in the calculation of a stock split.

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Stock-based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	9 Months Ended
	Jun. 30, 2011 stocksplit	Sep. 30, 2011	Sep. 30, 2010	Jun. 10, 2011
Stock-based Compensation
Stock split ratio	2
Equity Incentive Plan
Stock-based Compensation
Stock split ratio	2
Shares authorized to be issued under the plan (in shares)				2,000,000
Recorded compensation costs for the RSAs and SARs		$ 1.0	$ 0.8
Restricted Stock Awards (RSAs)
Stock-based Compensation
Awards granted (in shares)		85,426	76,572
Vesting period		Forty-eight months
Vesting period for director options (in months)		Twelve months
Weighted average grant date fair value (in dollars per share)		$ 17.44	$ 17.74