Restructuring Obligations and Charges (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
Restructuring obligations, beginning of period	$ 81	$ 81
Restructuring costs incurred		128
Cash payments		(209)
Restructuring obligations, end of period		0	$ 81
Relocation [Member]
Restructuring Reserve [Roll Forward]
Restructuring obligations, beginning of period	0	0
Restructuring costs incurred		42
Cash payments		(42)
Restructuring obligations, end of period		0	0
Contract Terminations [Member]
Restructuring Reserve [Roll Forward]
Restructuring obligations, beginning of period	31	31
Restructuring costs incurred		0	113
Cash payments		(31)
Restructuring obligations, end of period		0	31
Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring obligations, beginning of period	50	50
Restructuring costs incurred		86	1,033
Cash payments	$ (50)	(136)	(983)
Restructuring obligations, end of period		$ 0	$ 50