Stock-Based Compensation (Details) (Restricted Stock [Member], USD $)	6 Months Ended
Jun. 30, 2012
Restricted Stock [Member]
Balance, beginning	52,470
Granted, (in shares)	25,805
Vested, (in shares)	(28,154)
Balance, ending	50,121
Balance, fair value beginning	$ 29.86
Granted, fair value (in dollars per share)	$ 37.43
Vested, fair value (in dollars per share)	$ 28.02
Balance, fair value ending	$ 34.79

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan 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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- Definition

The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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