v3.8.0.1

UNIT-BASED COMPENSATION (Tables) | 12 Months Ended
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Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Summary of long-term incentive plan compensation expense | The following table summarizes information pertaining to our long-term incentive plan compensation expense:
| Units Outstanding December 31, |  | Transferred Units |  | Compensation Expense Year Ended December 31,
| 2017 |  | 2016 |  | March 1, 2016 |  | 2017 |  | 2016
|  |  |  |  |  |  | (Thousands of Dollars)
Restricted Units: |  |  |  |  |  |  |  |  |
Domestic employees | 736,746 |  |  | 647,340 |  |  | 586,524 |  |  | $ | 7,881 |  |  | $ | 5,980 |
Non-employee directors (NEDs) | 27,097 |  |  | 18,134 |  |  | 17,629 |  |  | 251 |  |  | 388 |
International employees | 58,107 |  |  | 50,609 |  |  | 49,121 |  |  | 595 |  |  | 715 |
Performance Units | 80,961 |  |  | 77,014 |  |  | 77,014 |  |  | — |  |  | 1,211 |
Total | 902,911 |  |  | 793,097 |  |  | 730,288 |  |  | $ | 8,727 |  |  | $ | 8,294 |
Restricted unit award activity | A summary of our restricted unit activity is as follows:
| Domestic Employees |  |  |  |
| Number of Restricted Units |  | Weighted- Average Grant-Date Fair Value Per Unit |  | Number of Restricted Units to NEDs |  | Number of Restricted Units to International Employees
Nonvested units as of January 1, 2016 | — |  |  | $ | — |  |  | — |  |  | — |
Transferred | 586,524 |  |  | 35.03 |  |  | 17,629 |  |  | 49,121 |
Granted | 246,070 |  |  | 47.70 |  |  | 8,730 |  |  | 20,107 |
Vested | (180,724 | ) |  | 35.50 |  |  | (8,225 | ) |  | (14,812 | )
Forfeited | (4,530 | ) |  | 35.03 |  |  | — |  |  | (3,807 | )
Nonvested units as of December 31, 2016 | 647,340 |  |  | 39.72 |  |  | 18,134 |  |  | 50,609 |
Granted | 307,009 |  |  | 29.56 |  |  | 17,110 |  |  | 24,533 |
Vested | (201,466 | ) |  | 38.74 |  |  | (8,147 | ) |  | (16,440 | )
Forfeited | (16,137 | ) |  | 40.00 |  |  | — |  |  | (595 | )
Nonvested units as of December 31, 2017 | 736,746 |  |  | $ | 35.95 |  |  | 27,097 |  |  | 58,107 |
Performance Units [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Summary of long-term incentive plan compensation expense | Performance units vested during the year ended December 31, 2017 with respect to 2016 performance were as follows:
| Vested Units |  | Actual Conversion Rate |  | Gross Number of Units Issued
2014 awards | 9,613 |  |  | 150 | % |  | 14,420 |
2015 awards | 9,878 |  |  | 150 | % |  | 14,818 |
2016 awards | 15,882 |  |  | 150 | % |  | 23,825 |
Total | 35,373 |  |  |  |  | 53,063 |
A summary of our performance units is shown below:
|  |  | Granted for Accounting Purposes
| Total Performance Units Awarded |  | Performance Units |  | Weighted-Average Grant Date Fair Value per Unit
Outstanding as of January 1, 2017 | 77,014 |  |  | 35,373 |  |  | $ | 31.75 |
Granted | 39,320 |  |  | 38,865 |  |  | 50.04 |
Vested | (35,373 | ) |  | (35,373 | ) |  | 31.75 |
Outstanding as of December 31, 2017 | 80,961 |  |  | 38,865 |  |  | $ | 50.04 |

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- Definition Tabular disclosure of components of a stock option or other award plan under which equity-based compensation is awarded to employees, typically comprised of the amount of unearned compensation (deferred compensation cost), compensation expense, and changes in the quantity and fair value of the shares (or other type of equity) granted, exercised, forfeited, and issued and outstanding pertaining to that plan. Disclosure may also include nature and general terms of such arrangements that existed during the period and potential effects of those arrangements on shareholders, effect of compensation cost arising from equity-based payment arrangements on the income statement, method of estimating the fair value of the goods or services received, or the fair value of the equity instruments granted, during the period, cash flow effects resulting from equity-based payment arrangements and, for registrants that accelerate vesting of out of the money share options, reasons for the decision to accelerate. + References Reference 1: 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=96867065&loc=d3e5070-113901 Reference 2: 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=96867065&loc=d3e5047-113901 + Details
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- Definition Tabular disclosure of the number and weighted-average grant date fair value for restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock units that were granted, vested, or forfeited 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=96867065&loc=d3e5070-113901 + Details
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