Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation (Share-Based Compensation Expense) (Details)

v2.4.0.6
Share-Based Compensation (Share-Based Compensation Expense) (Details) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense - Equity-based $ 4,428 [1] $ 3,058 [1] $ 4,305 [1]
Share-based compensation expense - Liability-based 2,916 1,335 1,396
Options [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense - Equity-based 0 24 206
RSUs [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense - Equity-based 4,210 2,832 3,898
Cash-settleable RSU awards [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense - Equity-based 0 0 0
Share-based compensation expense - Liability-based 2,916 1,335 1,396
Contribution 401K in Shares Plan [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense - Equity-based 218 202 201
General and Administrative Expense [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense - Equity-based 4,081 2,502 3,107
Portion Capitalized to Oil and Gas Properties [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense - Equity-based $ 3,263 $ 1,891 $ 2,594
[1] The portion of this share-based compensation expense that was included in general and administrative expense totaled $4,081, $2,502 and $3,107 for the same years respectively, and the portion capitalized to oil and gas properties was $3,263, $1,891 and $2,594, respectively.