Restructuring Activities (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($) position	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Restructuring and Related Activities [Abstract]
Number of positions impacted | position	21
Restructuring expense expected to incur	$ 1,500	$ 1,500
Restructuring expense incurred	700	700
Restructuring Reserve [Roll Forward]
Restructuring expenses		660	$ 0
Employee separation costs
Restructuring Reserve [Roll Forward]
Restructuring accruals - December 31, 2017		0
Restructuring expenses		660
Cash payments		0
Restructuring accruals - December 31, 2018	$ 660	$ 660	$ 0