Equity-Based Compensation Plans (Details 2) (USD $)	12 Months Ended
Dec. 31, 2012
Options outstanding	521,613
Weighted-average remaining contractual, outstanding	3 years 11 months
Weighted-average exercise price	$ 17.80
Options exercisable	445,613
Weighted-average exercise price	$ 19.15
$8.85 to $11.06
Options outstanding	75,000
Weighted-average remaining contractual, outstanding	9 years 7 months
Weighted-average exercise price	$ 9.76
Options exercisable
Weighted-average exercise price
$11.06 to $13.27
Options outstanding
Weighted-average exercise price
Options exercisable
Weighted-average exercise price
$13.27 to $15.48
Options outstanding	27,000
Weighted-average remaining contractual, outstanding	6 years 5 months
Weighted-average exercise price	$ 14.35
Options exercisable	27,000
Weighted-average exercise price	$ 14.35
$15.48 to $17.70
Options outstanding	164,384
Weighted-average remaining contractual, outstanding	3 years 7 months
Weighted-average exercise price	$ 16.61
Options exercisable	164,384
Weighted-average exercise price	$ 16.61
$17.70 to $19.91
Options outstanding	56,250
Weighted-average remaining contractual, outstanding	2 years 7 months
Weighted-average exercise price	$ 19.65
Options exercisable	56,250
Weighted-average exercise price	$ 19.65
$19.91 to $22.12
Options outstanding	198,979
Weighted-average remaining contractual, outstanding	1 year 11 months
Weighted-average exercise price	$ 21.76
Options exercisable	197,979
Weighted-average exercise price	$ 21.77

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

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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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

+ Details

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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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