Defined Contribution Benefit Plan (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Canada
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 14,000	$ 64,000
Employer matching contribution, percent of employees' eligible compensation	4.00%
401(k) Retirement Plan | United States
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 19,000	$ 0	$ 62,000
Viventia 401(k) Retirement Plan | United States
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 8,000