Investments (Details) - Summary of financial assets measured at fair value on a recurring basis - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Available-for-sales securities—current:
Total	$ 17,884	$ 19,217
Level 1 [Member]
Available-for-sales securities—current:
Total	3,136	4,549
Level 2 [Member]
Available-for-sales securities—current:
Total	14,748	14,668
Level 3 [Member]
Available-for-sales securities—current:
Total
Marketable securities [Member]
Available-for-sales securities—current:
Available-for-sale securities - current:		790
Marketable securities [Member] | Level 1 [Member]
Available-for-sales securities—current:
Available-for-sale securities - current:		790
Money market funds [Member]
Cash equivalents:
Cash equivalents:	3,136	3,759
Money market funds [Member] | Level 1 [Member]
Cash equivalents:
Cash equivalents:	3,136	3,759
Money market funds [Member] | Level 2 [Member]
Cash equivalents:
Cash equivalents:
Money market funds [Member] | Level 3 [Member]
Cash equivalents:
Cash equivalents:
U.S. Treasury securities [Member]
Available-for-sales securities—current:
Available-for-sale securities - current:	14,748	14,668
U.S. Treasury securities [Member] | Level 1 [Member]
Available-for-sales securities—current:
Available-for-sale securities - current:
U.S. Treasury securities [Member] | Level 2 [Member]
Available-for-sales securities—current:
Available-for-sale securities - current:	14,748	14,668
U.S. Treasury securities [Member] | Level 3 [Member]
Available-for-sales securities—current:
Available-for-sale securities - current: