Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation Allowance [Abstract]
Valuation allowance	$ 128,314,000	$ 160,783,000
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	32,500,000	23,500,000
Income Tax Uncertainties [Abstract]
Unrecognized tax benefits	655,000	5,020,000	$ 374,000
Income Tax Disclosure [Line Items]
Income tax receivables	100,000	1,800,000
Research and development tax credit carryforwards	13,350,000	19,694,000
Deferred Tax Liabilities, Undistributed Foreign Earnings	900,000	900,000
Internal Revenue Service (IRS)
Income Tax Disclosure [Line Items]
Operating loss carryforwards	$ 321,200,000	$ 406,000,000.0