XML 138 R41.htm IDEA: XBRL DOCUMENT v3.20.1
Marketable Securities - Schedule of Fair Value Marketable Securities By Type of Security (Detail) - USD ($)
$ in Thousands
Mar. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Marketable Securities [Line Items]      
Amortized Cost $ 15,079 $ 57,650 $ 101,027
Unrealized Gains 32 49 4
Unrealized Losses     (45)
Fair Value 15,111 57,699 100,986
U.S. Government Agency Treasuries and Securities      
Marketable Securities [Line Items]      
Amortized Cost 15,079 57,650 101,027
Unrealized Gains 32 49 4
Unrealized Losses     (45)
Fair Value $ 15,111 $ 57,699 $ 100,986