Restructuring Plan - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Restructuring Costs [Abstract]
Restructuring costs	$ 640	$ 481	$ 130	$ 640	$ 611	$ 7,078
Restructuring costs, liability						$ 606
Restructuring and related cost, expected cost	$ 1,762	$ 1,623		$ 1,762	$ 1,623