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Commitments and Contingencies - Additional Information (Detail)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2019
USD ($)
lease
Jun. 30, 2018
USD ($)
Jun. 30, 2019
USD ($)
lease
Jun. 30, 2018
USD ($)
Other Commitments [Line Items]        
Number of leases | lease 4   4  
Expenses incurred for the properties listed $ 0.1 $ 0.1 $ 0.3 $ 0.2
Line of credit        
Other Commitments [Line Items]        
Letters of credit, outstanding $ 7.4   $ 7.4