Income Taxes (income Taxes) DTA Valuation Allowance Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes (DTA Valuation Allowance Rollforward) [Abstract]
Balance at the beginning of the period	$ 40,070		$ 45,255
Net operating loss carryforwards generated	2,925	$ 2,509	3,050
R&D tax credit increase	1,609	1,014	1,121
Depreciation and amortization increase	(605)	925	237
Reserves and accruals decrease	(312)	(581)	(1,479)
Deferred tax assets increase	(3,251)	(9,052)	$ (13)
Balance at the end of the period	$ 40,436	$ 40,070