Restructuring (Restructuring Liability) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Restructuring Reserve [Roll Forward]
Balance, Beginning of the year	$ 977	$ 2,338
Severance and other associated costs	279	4,468
Cash payments	(1,184)	(5,829)
Balance, End of period	$ 72	$ 977