Restructuring - Restructuring Reserve (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Balance at January 1, 2017	$ 402	$ 0
Additions		1,786
Accretion of lease obligations	21	31
Adjustment of lease obligations	90	(155)
Write-offs		(86)
Payments	(163)	(1,174)
Balance at December 31, 2017	350	402
Severance and Related Benefits
Restructuring Reserve [Roll Forward]
Balance at January 1, 2017	62	0
Additions		770
Payments	(62)	(708)
Balance at December 31, 2017	0	62
Facilities
Restructuring Reserve [Roll Forward]
Balance at January 1, 2017	340	0
Additions		830
Accretion of lease obligations	21	31
Adjustment of lease obligations	90	(155)
Write-offs		9
Payments	(101)	(375)
Balance at December 31, 2017	350	340
Other
Restructuring Reserve [Roll Forward]
Balance at January 1, 2017	0	0
Additions		186
Accretion of lease obligations		0
Adjustment of lease obligations	0	0
Write-offs		(95)
Payments	0	(91)
Balance at December 31, 2017	$ 0	$ 0