Income Taxes (Net Deferred Tax Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets [Abstract]
United States federal net operating loss carryforwards	$ 85,270	$ 62,983
Deferred expenses	3,226	660
Research and development tax credit carryforwards	19,694	24,523
Stock-based compensation	2,697	2,603
State net operating loss carryforwards	13,880	11,971
Foreign net operating loss carryforwards	34,079	31,254
Deferred revenue	900	67
Equipment, software, and leasehold improvements	2,922	2,642
Intangibles	6,216	13
Net unrealized gains and basis differences on investments	0	1,193
Other	455	839
Gross deferred tax assets	172,035	138,748
Less valuation allowance	160,783	137,246
Gross deferred tax assets, net of valuation allowance	11,252	1,502
Deferred tax liabilities:
Other intangible assets	(4,667)	(155)
Undistributed foreign earnings	909	1,001
Other	(838)	(663)
Deferred Tax Liabilities, Prepaid Expenses	(2,916)	0
Gross deferred tax liabilities	(11,663)	(1,819)
Net deferred tax assets (liabilities)	(411)	(317)
Right of use tax assets	2,696	0
Right of use tax liability	$ 2,333	$ 0