Stock-Based Compensation (Details 4) (USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Restricted Stock
Number of Shares
Outstanding at the beginning of the period (in shares)	106,838	53,945
Granted (in shares)	106,289	65,285	54,502
Vested (in shares)	(25,248)	(11,128)
Forfeited (in shares)	(2,115)	(1,264)	(557)
Outstanding unvested at the end of the period (in shares)	185,764	106,838	53,945
Weighted-Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 21.47	$ 17.15
Granted (in dollars per share)	$ 17.95	$ 24.23	$ 17.15
Vested (in dollars per share)	$ 21.07	$ 17.13
Forfeited (in dollars per share)	$ 18.91	$ 17.74	$ 17.18
Outstanding unvested at the end of the period (in dollars per share)	$ 19.54	$ 21.47	$ 17.15
Restricted Stock \| Various employees \| Minimum
Additional disclosures
Vesting period	3 years
Restricted Stock \| Various employees \| Maximum
Additional disclosures
Vesting period	5 years
Restricted Stock \| Eligible members of the Board of Directors
Additional disclosures
Vesting period	3 years
Performance Awards
Number of Shares
Outstanding at the beginning of the period (in shares)	74,435	40,256
Granted (in shares)	41,755	34,179	40,741
Vested (in shares)	(30,855)
Forfeited (in shares)	(10,412)		(485)
Outstanding unvested at the end of the period (in shares)	74,923	74,435	40,256
Weighted-Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 20.39	$ 17.18
Granted (in dollars per share)	$ 17.48	$ 24.18	$ 17.18
Vested (in dollars per share)	$ 17.18
Forfeited (in dollars per share)	$ 17.43		$ 17.18
Outstanding unvested at the end of the period (in dollars per share)	$ 20.51	$ 20.39	$ 17.18
Shares earned by the participants	30,855
Target awards earned during the performance period (as a percent)	76.60%
Performance Awards \| Minimum
Weighted-Average Grant Date Fair Value
Potential payout as a percentage of target shares	50.00%
Performance Awards \| Maximum
Weighted-Average Grant Date Fair Value
Potential payout as a percentage of target shares	200.00%

Represents the percentage of target awards earned for the performance period.

No definition available.

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- Definition

The percentage of target shares, an employee can earn, under the plan.

+ References

No definition available.

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- Definition

Period 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, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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- Definition

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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- Definition

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).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-SubTopic 10

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Paragraph A240

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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- Definition

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

Number of non-option equity instruments exercised by participants.

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