Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax [Line Items]
Income tax receivables	$ 1.8	$ 3.6
Income taxes receivable, current	900,000
Income taxes receivable, noncurrent	900,000
Valuation Allowance [Abstract]
Change in valuation allowance	(23.5)	100,000
Valuation allowance	160,783,000	137,246,000
Research and development tax credit carryforwards	19,694,000	24,523,000
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	23.5	(100,000)
Income Tax Uncertainties [Abstract]
Unrecognized tax benefits	5,020,000	374,000	$ 358,000
Deferred Tax Liabilities, Undistributed Foreign Earnings	0.9	1,000,000.0
Accrued interest and penalties related to uncertain tax positions	0.6	0
Income Tax Examination [Abstract]
Accrued interest and penalties related to uncertain tax positions	0.6	0
Deferred Tax Liabilities, Undistributed Foreign Earnings	0.9	1,000,000.0
Internal Revenue Service (IRS)
Valuation Allowance [Abstract]
Operating loss carryforwards	$ 406,000,000.0	$ 299,900,000