XML 39 R29.htm IDEA: XBRL DOCUMENT v3.20.2
Fair Value Measurements - Additional Information (Details) - USD ($)
6 Months Ended
Jun. 30, 2020
Dec. 31, 2019
Fair Value Disclosures [Abstract]    
Financial instruments transferred among fair value hierarchy levels $ 0  
Cash equivalents included of available-for-sale securities 7,600,000 $ 15,000,000.0
Available for sale securities with contractual maturities of three months to one year. 205,700,000 279,700,000
Available for sale securities with contractual maturities greater than one year $ 14,400,000 $ 39,400,000