Organization and Summary of Significant Accounting Policies (Details 6) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair value for financial assets	$ 19,049	$ 18,600
Level 1
Fair value for financial assets	1,258	1,137
Level 2
Fair value for financial assets	17,791	17,463
Level 3
Fair value for financial assets	0	0
Money Market Funds
Fair value for financial assets	1,258	1,137
Money Market Funds | Level 1
Fair value for financial assets	1,258	1,137
Money Market Funds | Level 2
Fair value for financial assets	0	0
Money Market Funds | Level 3
Fair value for financial assets	0	0
Certificates of Deposit
Fair value for financial assets	492	475
Certificates of Deposit | Level 1
Fair value for financial assets	0	0
Certificates of Deposit | Level 2
Fair value for financial assets	492	475
Certificates of Deposit | Level 3
Fair value for financial assets	0	0
Commercial Paper
Fair value for financial assets	3,273	6,911
Commercial Paper | Level 1
Fair value for financial assets	0	0
Commercial Paper | Level 2
Fair value for financial assets	3,273	6,911
Commercial Paper | Level 3
Fair value for financial assets	0	0
Corporate Notes and Bonds
Fair value for financial assets	9,427	7,933
Corporate Notes and Bonds | Level 1
Fair value for financial assets	0	0
Corporate Notes and Bonds | Level 2
Fair value for financial assets	9,427	7,933
Corporate Notes and Bonds | Level 3
Fair value for financial assets	0	0
U.S. Government Agency Securities
Fair value for financial assets	4,599	2,144
U.S. Government Agency Securities | Level 1
Fair value for financial assets	0	0
U.S. Government Agency Securities | Level 2
Fair value for financial assets	4,599	2,144
U.S. Government Agency Securities | Level 3
Fair value for financial assets	$ 0	$ 0