Earnings Per Share (details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Earnings per share of common stock [Abstract]
Net income	$ 1,409	$ 2,193	$ 42,016	$ 42,966
Average common shares outstanding - basic	26,812	26,673	26,797	26,671
Additional shares for stock based compensation plans	84	54	82	54
Average common shares outstanding - diluted	26,896	26,727	26,879	26,725
Earnings per share of common stock - basic	$ 0.05	$ 0.08	$ 1.57	$ 1.61
Earnings per share of common stock - diluted	$ 0.05	$ 0.08	$ 1.56	$ 1.61
Earnings Per Share, Diluted, Other Disclosures [Abstract]
Antidilutive securities excluded from computation of earnings per share Amount	1,180	8,946	943	3,883

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Antidilution

-URI http://asc.fasb.org/extlink&oid=6505113

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 128

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Diluted Earnings Per Share

-URI http://asc.fasb.org/extlink&oid=6510752

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-Name Accounting Standards Codification

-Topic 260

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Contingent Stock Agreement

-URI http://asc.fasb.org/extlink&oid=6508534

+ Details

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

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-Section 55

-Paragraph 52

-URI http://asc.fasb.org/extlink&oid=6945512&loc=d3e4984-109258

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-Name Regulation S-X (SX)

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-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

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-Number 210

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-Topic 260

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6920599&loc=d3e1252-109256

+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

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-Subparagraph (SX 210.7-04.22)

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-Appendix A

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-Glossary Other Comprehensive Income

-URI http://asc.fasb.org/extlink&oid=6519514

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Reference 12: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-Glossary Net Income

-URI http://asc.fasb.org/extlink&oid=6518256

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-Number 210

-Section 04

-Paragraph 20

-Article 9

+ Details

- Definition

The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

+ References+ Details

- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References+ Details

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

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

-Publisher FASB

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-Subparagraph (a)

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-Publisher FASB

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-Glossary Weighted-Average Number of Common Shares Outstanding

-URI http://asc.fasb.org/extlink&oid=6528421

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+ Details