Stock-Based Compensation Plans (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement, Noncash Expense [Abstract]

Schedule of components of stock compensation expense

The components of stock-based compensation expense were as follows:

	Three months ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
	(in thousands)				(in thousands)
2007 Stock Incentive Plan	$	703	$	1,143	$	1,728	$	2,402
2018 Stock Incentive Plan	2,237		975		3,297		975
Employee Stock Purchase Plan	75		4		107		10
Total Stock Compensation Expense	$	3,015	$	2,122	$	5,132	$	3,387

Summary of restricted stock activity

The following table summarizes restricted stock activity under the 2007 and 2018 Plans during the six months ended June 30, 2020:

	Shares
Balance as of December 31, 2019	505,467
Shares granted	307,600
Shares forfeited	—
Shares vested	(229,414	)
Balance as of June 30, 2020	583,653