Restructuring (Details)	3 Months Ended				12 Months Ended
	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017	Mar. 31, 2016 USD ($) position	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Total termination charges	$ 800,000				$ 800,000
Severance benefits and other one-time termination costs	660,000				660,000
Cash expenditures				$ 820,000
Reduction in workforce, as a percent			60.00%
Restructuring expense		$ 50,000			1,000,000
Termination fee	270,000
Restructuring charges
Balance at the beginning of the period					5,000
Restructuring charge					1,321,000	$ 676,000
Cash payments					(848,000)
Balance at the end of the period	478,000				478,000	5,000
Hyderabad India
Number of positions/employees terminated | position				18
United States
Number of positions/employees terminated | position				12
Workforce reduction
Restructuring charges
Restructuring charge					458,000
Cash payments					(458,000)
Facility related
Restructuring charges
Restructuring charge					269,000
Cash payments					(180,000)
Balance at the end of the period	89,000				89,000
Contractual obligations and other termination costs
Restructuring charges
Balance at the beginning of the period					5,000
Restructuring charge					594,000
Cash payments					(210,000)
Balance at the end of the period	$ 389,000				$ 389,000	$ 5,000