Stock Based Compensation, Stock Options Outstanding By Exercise Price Range (Details) (USD $)	3 Months Ended
Mar. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding stock options, number (in shares)	110,586
Outstanding stock option, weighted average exercise price (in dollars per share)	$ 12.42
Outstanding stock option, weighted average remaining contractual life	6 years 1 month 6 days
Exercisable stock options, number (in shares)	73,519
Exercisable stock option, weighted average exercise price (in dollars per shares)	$ 12.82
Exercisable stock options, weighted average remaining contractual life	5 years 3 months 18 days
$9.00 - $10.99 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	$ 9.00
Exercise price range, upper range limit (in dollars per share)	$ 10.99
Outstanding stock options, number (in shares)	25,360
Outstanding stock option, weighted average exercise price (in dollars per share)	$ 9.00
Outstanding stock option, weighted average remaining contractual life	5 years 9 months 18 days
Exercisable stock options, number (in shares)	20,285
Exercisable stock option, weighted average exercise price (in dollars per shares)	$ 9.00
Exercisable stock options, weighted average remaining contractual life	5 years 9 months 18 days
$11.00 - $12.99 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	$ 11.00
Exercise price range, upper range limit (in dollars per share)	$ 12.99
Outstanding stock options, number (in shares)	65,708
Outstanding stock option, weighted average exercise price (in dollars per share)	$ 12.04
Outstanding stock option, weighted average remaining contractual life	7 years 3 months 18 days
Exercisable stock options, number (in shares)	33,716
Exercisable stock option, weighted average exercise price (in dollars per shares)	$ 12.04
Exercisable stock options, weighted average remaining contractual life	6 years 8 months 12 days
$17.00 - $18.99 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	$ 17.00
Exercise price range, upper range limit (in dollars per share)	$ 18.99
Outstanding stock options, number (in shares)	19,518
Outstanding stock option, weighted average exercise price (in dollars per share)	$ 18.15
Outstanding stock option, weighted average remaining contractual life	2 years 6 months
Exercisable stock options, number (in shares)	19,518
Exercisable stock option, weighted average exercise price (in dollars per shares)	$ 18.15
Exercisable stock options, weighted average remaining contractual life	2 years 6 months

Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

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- Definition

Weighted average remaining contractual term of exercisable stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

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- Definition

The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(iii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(a, b)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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- Definition

The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

+ References

+ Details

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- Definition

Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

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- Definition

The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

+ Details

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