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Stock-Based Compensation | 3 Months Ended
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Mar. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |
Stock-Based Compensation | 7. STOCK-BASED COMPENSATION We recognize the cost of employee compensation received in the form of equity instruments based on the grant date fair value of those awards. The table below sets forth the total amount of stock-based compensation expense for the three months and quarters ended March 31, 2016 and 2015.
|  | Quarter Ended March 31, |
|  | 2016 |  |  | 2015 |
Stock-based compensation expense: |  |  | (Thousands of dollars) |
Time-based restricted stock units |  | $ | 619 |  |  | $ | 637 |
Performance-based restricted stock units |  |  | 871 |  |  |  | 1,082 |
Total stock-based compensation expense |  | $ | 1,490 |  |  | $ | 1,719 |
During the quarter ended March 31, 2016, we awarded 303,061 performance-based restricted stock units to managerial employees. During the quarter ended March 31, 2015, we awarded 18,930 time-based and 151,566 performance-based restricted stock units to managerial employees, respectively.

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- Definition The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 40 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6418621&loc=d3e17540-113929 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 50 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=51659978&loc=d3e25284-112666 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5444-113901 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 + Details
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