Income Taxes (Effective Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Tax at Federal statutory rate	21.00%	21.00%	35.00%
State taxes - net of Federal benefit	1.80%	6.50%	3.30%
Research and development incentives	1.20%	2.10%	0.60%
Foreign rate differential	0.80%	(1.70%)	0.60%
Valuation allowances	(33.70%)	(1.80%)	1.50%
Change in foreign tax rates	0.00%	0.00%	(0.60%)
Increase in tax reserves	(0.80%)	(1.30%)	(0.20%)
Stock compensation expense	0.20%	(1.70%)	(1.70%)
U.S. taxation of foreign earnings	0.40%	(2.40%)	(4.40%)
Non-deductible meals and entertainment	(0.20%)	(0.10%)	(0.10%)
Change in U.S. tax rate	0	0	0.348
Transition tax on unremitted foreign earnings	0	0.026	(0.171)
Other	(0.90%)	2.40%	(1.40%)
Effective tax rate	(10.20%)	25.60%	50.30%
Valuation allowance related to federal and state deferred tax assets	$ 13.3