Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation (Schedule of Share-based Compensation Expense) (Details)

v3.6.0.2
Share-Based Compensation (Schedule of Share-based Compensation Expense) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense - Equity-based $ 4,813 $ 4,063 $ 4,493
Share-based compensation expense - Liability-based 12,285 11,437 6,918
Share-based compensation - capitalized oil and gas properties 7,376 6,201 4,176
RSUs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense - Equity-based 4,536 3,797 4,223
Cash-settleable RSU awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense - Liability-based 12,285 11,437 6,918
Contribution (401)K in Shares Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense - Equity-based 277 266 270
General and Administrative Expense [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
share-based compensation $ 9,722 $ 9,299 $ 7,235