Cash Equivalents and Investments (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Marketable Securities [Line Items]
Amortized Cost	$ 70,016,000	$ 57,436,000
Gains	78,000	21,000
Losses	0	0
Credit Losses	0
Estimated Fair Value	$ 70,094,000	$ 57,457,000
Remaining contractual maturity period	3 years	3 years
Impairments of assets	$ 0
Cash equivalents
Marketable Securities [Line Items]
Estimated Fair Value	28,059,000	$ 5,381,000
Short-term investments
Marketable Securities [Line Items]
Estimated Fair Value	42,035,000	42,829,000
Long-term investments
Marketable Securities [Line Items]
Estimated Fair Value		9,247,000
Money market funds
Marketable Securities [Line Items]
Amortized Cost	28,059,000	5,381,000
Gains	0	0
Losses	0	0
Credit Losses	0
Estimated Fair Value	28,059,000	5,381,000
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	9,984,000	11,892,000
Gains	0	0
Losses	0	0
Credit Losses	0
Estimated Fair Value	9,984,000	11,892,000
Corporate notes
Marketable Securities [Line Items]
Amortized Cost	11,161,000	18,369,000
Gains	25,000	11,000
Losses	0	0
Credit Losses	0
Estimated Fair Value	11,186,000	18,380,000
U.S. government securities
Marketable Securities [Line Items]
Amortized Cost	13,764,000	11,291,000
Gains	40,000	4,000
Losses	0	0
Credit Losses	0
Estimated Fair Value	13,804,000	11,295,000
U.S. government agency bonds
Marketable Securities [Line Items]
Amortized Cost	3,498,000
Gains	1,000
Losses	0
Credit Losses	0
Estimated Fair Value	3,499,000
U.S. asset-backed securities
Marketable Securities [Line Items]
Amortized Cost	3,550,000	10,503,000
Gains	12,000	6,000
Losses	0	0
Credit Losses	0
Estimated Fair Value	$ 3,562,000	$ 10,509,000