Income Taxes Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets
Net operating loss carryforwards	$ 71,270,000	$ 59,126,000
Research and development credits	6,586,000	5,780,000
Stock-based compensations expense	2,516,000	1,946,000
Deferred rent and other expenses	812,000	458,000
Deferred revenue	4,468,000	4,037,000
Operating lease liability	102,000
Patent costs/amortization	5,111,000	4,881,000
Gross deferred tax assets	90,865,000	76,228,000
Deferred Tax Liabilities
Depreciation	(57,000)	(66,000)
Operating lease right-of-use asset	(82,000)
Gross deferred tax liabilities	(139,000)	(66,000)
Depreciation	(57,000)	(66,000)
Gross deferred tax liabilities	(139,000)	(66,000)
Net deferred tax assets before valuation allowance	(90,726,000)	(76,162,000)
Valuation allowance	(90,726,000)	(76,162,000)
Net deferred tax assets	$ 0	$ 0