Income Tax Matters Income Tax Matters Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Tax Credit Carryforward [Line Items]
Net operating loss	$ 121,300,000
Tax credit carryforward	5,700,000
Increase (decrease) in valuation allowance	1,500,000	$ (4,600,000)	$ (2,700,000)
Unrecognized tax benefits	4,100,000	1,500,000	1,500,000	$ 1,800,000
Amount that ould be reflected in income tax provision if unrecognized tax benefits are recognized	900,000
Accrued interest and penalties on unrecognized tax benefits	300,000	200,000
Accrued interest and penalties on unrecognized tax benefits, current	0
(Decrease) increase in interest and penalty	(100,000)	$ (100,000)	$ (100,000)
Research Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	$ 7,700,000