Cash, Cash Equivalents and Investments (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash, cash equivalents and investments [Abstract]
Cash	$ 72,602,000	$ 26,892,000
Cash equivalents [Abstract]
Total cash and cash equivalents	72,602,000	26,892,000
Amortized Cost	5,963,000	9,430,000
Cash, cash equivalents and investments, amortized costs	78,565,000	36,322,000
Gross Unrealized Gain	5,000	6,000
Gross Unrealized (Loss)	(2,000)	(9,000)
Fair Value	5,966,000	9,427,000
Cash, cash equivalents and investments, amortized costs	78,568,000	36,319,000
Contractual maturities on investments, amortized cost basis [Abstract]
Due within 1 year	240,000	9,430,000
Due after 1 through 5 years	5,723,000
Investments, amortized cost	5,963,000	9,430,000
Contractual maturities on investments, fair value basis [Abstract]
Due within 1 year	240,000	9,427,000
Due after 1 through 5 years	5,726,000
Investments, fair value	5,966,000	9,427,000
Debt Securities, Available-for-sale, Unrealized Loss	2,000
Total Investments
Cash equivalents [Abstract]
Amortized Cost	5,963,000	9,430,000
Gross Unrealized Gain	5,000	6,000
Gross Unrealized (Loss)	(2,000)	(9,000)
Fair Value	5,966,000	9,427,000
Contractual maturities on investments, amortized cost basis [Abstract]
Investments, amortized cost	5,963,000	9,430,000
Contractual maturities on investments, fair value basis [Abstract]
Investments, fair value	5,966,000	9,427,000
Certificates of Deposit [Member]
Cash equivalents [Abstract]
Amortized Cost	2,880,000	2,400,000
Gross Unrealized Gain	5,000	2,000
Fair Value	2,885,000	2,402,000
Contractual maturities on investments, amortized cost basis [Abstract]
Investments, amortized cost	2,880,000	2,400,000
Contractual maturities on investments, fair value basis [Abstract]
Investments, fair value	2,885,000	2,402,000
Corporate Bonds [Member]
Cash equivalents [Abstract]
Amortized Cost	3,083,000	7,030,000
Gross Unrealized Gain		4,000
Gross Unrealized (Loss)	(2,000)	(9,000)
Fair Value	3,081,000	7,025,000
Contractual maturities on investments, amortized cost basis [Abstract]
Investments, amortized cost	3,083,000	7,030,000
Contractual maturities on investments, fair value basis [Abstract]
Investments, fair value	$ 3,081,000	$ 7,025,000