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