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Compensation Plans (Tables) | 3 Months Ended
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Mar. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |
Schedule of stock option grants under prior stock option plans | A summary of activity associated with the Company’s Stock Option Plan for the three months ended March 31, 2013, is presented in the following table:
| Shares |  | Weighted- Average Exercise Price |  | Aggregate Intrinsic Value (in thousands)
Outstanding, at beginning of year | 267,846 |  |  | $ | 14.95 |  |  | $ | 9,983 |
Exercised | (54,187 | ) |  | $ | 14.24 |  |  | $ | 2,393 |
Forfeited | — |  |  | $ | — |  |  |
Outstanding, at end of quarter | 213,659 |  |  | $ | 15.11 |  |  | $ | 9,424 |
Vested and exercisable, at end of quarter | 213,659 |  |  | $ | 15.11 |  |  | $ | 9,424 |
Summary of cash payments made or accrued under the Net Profits Plan | Cash payments made or accrued under the Company’s Net Profits Interest Bonus Plan (“Net Profits Plan”) that have been recorded as either general and administrative expense or exploration expense are presented in the table below:
| For the Three Months Ended March 31,
| 2013 |  | 2012
| (in thousands)
General and administrative expense | $ | 3,786 |  |  | $ | 4,412 |
Exploration expense | 374 |  |  | 525 |
Total | $ | 4,160 |  |  | $ | 4,937 |

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- Definition Tabular disclosure of the number and weighted-average exercise prices (or conversion ratios) for share options (or share units) that were outstanding at the beginning and end of the year, vested and expected to vest, exercisable or convertible at the end of the year, and the number of share options or share units that were granted, exercised or converted, forfeited, and expired during the year. + 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) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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