Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of Stock Based Compensation Expense

Our stock-based compensation expense was as follows for the three and six months ended June 30, 2019 and 2018 (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Restricted stock units	$	235	$	974	$	3,328	$	2,137
Performance units		231		910		2,990		1,639
Restricted stock		86		95		235		184
Total expense	$	552	$	1,979	$	6,553	$	3,960

Summary of Employee Restricted Stock Unit Awards Activity

A summary of employee restricted stock unit awards activity during the six months ended June 30, 2019 is as follows:

	Number of shares			Weighted average grant date fair value		Aggregate intrinsic value (in thousands)
Total awarded and unvested, December 31, 2018		233,960		$	29.27	$	3,685
Granted		407,714			6.46
Vested		(204,418	)		29.31
Forfeited		(485	)		31.78
Total awarded and unvested, June 30, 2019		436,771		$	7.95	$	2,664

Summary of Performance Stock Unit Awards Activity

A summary of performance stock unit awards activity during the six months ended June 30, 2019 is as follows

	Number of shares			Weighted average grant date fair value		Aggregate intrinsic value (in thousands)
Total awarded and unvested, December 31, 2018		346,589		$	27.68	$	716
Granted		243,600			7.25
Vested		(266,411	)		27.55
Forfeited		(16,483	)		24.47
Total awarded and unvested, June 30, 2019		307,295		$	11.76	$	—

Performance Units [Member]

Assumptions Used to Determine Fair Value of Performance Stock Units Granted

The following table presents the assumptions used to determine the fair value for performance stock units granted during the six months ended June 30, 2019 and 2018:

	Six Months Ended June 30,
	2019			2018
Volatility		65.10	%		89.70	%
Risk-free interest rate		1.83	%		2.37	%