Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Stock Based Compensation Expense

Our stock-based compensation expense was as follows for the three months ended March 31, 2018 and 2017 (in thousands):

	Three Months Ended March 31,
	2018		2017
Restricted stock units	$	1,164	$	1,247
Performance units		728		734
Restricted stock issued to directors		89		100
Total expense	$	1,981	$	2,081

Summary of Restricted Stock Unit Awards Activity

A summary of restricted stock unit awards activity during the three months ended March 31, 2018 is as follows:

	Number of shares			Weighted average grant date fair value		Aggregate intrinsic value (in thousands)
Total awarded and unvested, December 31, 2017		4,057,354		$	2.48	$	9,738
Granted		1,498,524			1.70
Vested		(1,378,403	)		3.17
Forfeited		(6,512	)		2.15
Total awarded and unvested, March 31, 2018		4,170,963		$	1.97	$	6,006

Summary of Performance Stock Unit Awards Activity

A summary of performance stock unit awards activity during the three months ended March 31, 2018 is as follows:

	Number of shares			Weighted average grant date fair value		Aggregate intrinsic value (in thousands)
Total awarded and unvested, December 31, 2017		3,966,377		$	1.82	$	11,257
Granted		1,498,524			1.92
Vested		—			—
Forfeited		(9,768	)		1.94
Total awarded and unvested, March 31, 2018		5,455,133		$	1.84	$	2,856

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 three months ended March 31, 2018 and 2017:

	Three Months Ended March 31,
	2018			2017
Volatility		89.70	%		50.41	%
Risk-free interest rate		2.37	%		1.34	%