Restructuring - Narrative (Details)	3 Months Ended
	Mar. 31, 2017 USD ($) employee	Dec. 31, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, number of positions eliminated | employee	20
Additions	$ 674,000		$ 0
Additional restructuring charges expected	400,000
Cash and cash equivalents	14,970,000	$ 16,629,000	$ 30,140,000	$ 34,640,000
Debt obligations	0
Impact of restructuring activities on operating expenses, excluding restructuring and asset impairment charges	(700,000)	$ (1,500,000)
Restructuring Initiative 2017
Restructuring Cost and Reserve [Line Items]
Restructuring initiative, reduction of annual operating costs, amount	10,000,000
Severance and Related Benefits
Restructuring Cost and Reserve [Line Items]
Additions	643,000
Facilities
Restructuring Cost and Reserve [Line Items]
Additions	19,000
Other
Restructuring Cost and Reserve [Line Items]
Additions	$ 11,000