Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2018

Stock-based Compensation

Summary of the stock-based compensation activity

	Quarter ended September 30,				Nine months ended September 30,
	2018		2017		2018		2017
	(in thousands)
Grants:
Units:
Performance-based RSUs		—		—		524		694
Stock options		—		—		674		861
Time-based RSUs		5		3		321		408
Grant date fair value:
Performance-based RSUs	$	—	$	—	$	12,791	$	12,512
Stock options		—		—		6,147		5,772
Time-based RSUs		100		58		7,803		7,359
Total	$	100	$	58	$	26,741	$	25,643
Vestings and exercises:
Performance-based RSUs vested		—		—		774		446
Stock options exercised		55		9		285		34
Time-based RSUs vested		1		4		245		165
Compensation expense	$	8,532	$	4,243	$	20,766	$	14,633