Income Taxes - Narrative (Details)	12 Months Ended
	Dec. 31, 2016 USD ($)
Operating loss carryforwards (NOLs)
Interest and/or penalties incurred	$ 0
Federal
Operating loss carryforwards (NOLs)
NOLs	106,700,000
California
Operating loss carryforwards (NOLs)
NOLs	87,400,000
Foreign Tax Authority [Member]
Operating loss carryforwards (NOLs)
NOLs	400,000
R&D credits | Federal
Operating loss carryforwards (NOLs)
Tax credits	2,000,000
R&D credits | California Franchise Tax Board [Member]
Operating loss carryforwards (NOLs)
Tax credits	$ 800,000