Schedule of Available for Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Cash and cash equivalents [Abstract]
Cash and Cash Equivalents, Amortized Cost	$ 31,242	$ 25,704
Cash And Cash Equivalents, Gross Unrealized Gains	0	0
Cash And Cash Equivalents, Gross Unrealized Losses	0	0
Cash and cash equivalents	31,242	25,704
Short-term Investments [Abstract]
AFS Securities, Amortized Cost Basis	179,071	203,727
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	929	499
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	5	62
Short-term investments	179,995	204,164
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Cash, Cash Equiv. And S-T Investments, Amortized Cost	210,313	229,431
Cash, Cash Equivalents And Short Term Investments, Unrealized Gains	929	499
Cash, Cash Equivalents And Short Term Investments, Unrealized Losses	5	62
Cash, cash equivalents and short-term investments	211,237	229,868
Demand deposits and other cash
Cash and cash equivalents [Abstract]
Cash and Cash Equivalents, Amortized Cost	24,540	21,618
Cash And Cash Equivalents, Gross Unrealized Gains	0	0
Cash And Cash Equivalents, Gross Unrealized Losses	0	0
Cash and cash equivalents	24,540	21,618
Money market funds
Cash and cash equivalents [Abstract]
Cash and Cash Equivalents, Amortized Cost	6,702	4,086
Cash And Cash Equivalents, Gross Unrealized Gains	0	0
Cash And Cash Equivalents, Gross Unrealized Losses	0	0
Cash and cash equivalents	6,702	4,086
Commercial paper in STI
Short-term Investments [Abstract]
AFS Securities, Amortized Cost Basis	7,494	12,861
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	7
Short-term investments	7,497	12,854
U.S. government agency securities
Short-term Investments [Abstract]
AFS Securities, Amortized Cost Basis		3,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax		0
Short-term investments		3,000
Corporate Debt Securities
Short-term Investments [Abstract]
AFS Securities, Amortized Cost Basis	171,577	187,866
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	926	499
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	5	55
Short-term investments	$ 172,498	$ 188,310