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Marketable Securities Marketable Securities (Tables)
9 Months Ended
Sep. 30, 2020
Marketable Securities [Abstract]  
Available-for-sale Securities [Table Text Block]
The schedule of maturities at September 30, 2020 and December 31, 2019 is as follows:
Maturities as of
September 30, 2020
Maturities as of
December 31, 2019
1 Year or Less1 to 4 Years1 Year or Less1 to 4 Years
Certificates of deposit$33,332 $ $40,521 $— 
Total$33,332 $ $40,521 $—