Stock-Based Compensation

6 Months Ended

Jun. 30, 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 six months and quarters ended June 30, 2016 and 2015.

	Quarter Ended				Six Months Ended
	June 30,				June 30,
	2016		2015		2016		2015
	(Thousands of dollars)
Stock-based compensation expense:
Time-based restricted units	$	597	$	571	$	1,216	$	1,208
Performance-based restricted units		809		1,069		1,680		2,151
Total stock-based compensation expense	$	1,406	$	1,640	$	2,896	$	3,359

During the quarter and six months ended June 30, 2016, 14,288 time-based restricted units were awarded to managerial employees.

During the quarter and six months ended June 30, 2016, 5,102 and 308,163 performance-based restricted units were awarded to managerial employees, respectively.

During the quarter and six months ended June 30, 2015, 1,118 and 20,048 time-based restricted units were awarded to managerial employees, respectively. During the quarter and six months ended June 30, 2015, 151,566 performance based restricted units were awarded to managerial employees.