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Commitments and Contingencies - Additional Information (Detail) - USD ($)
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2018
Dec. 29, 2015
Other Commitments [Line Items]        
Outstanding letter of credit, amount $ 1,100,000 $ 1,100,000    
Outstanding performance and payment of bonds       $ 5,000,000
Amounts drawn against outstanding letters of credit or performance bond 0 0    
Restricted Escrow Deposits 1,000,000   $ 1,000,000  
Performance Bonds [Member]        
Other Commitments [Line Items]        
Outstanding performance and payment of bonds $ 7,700,000 $ 4,500,000