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Basis of Presentation and Significant Accounting Policies (Details) - USD ($)
Jun. 30, 2020
Dec. 31, 2019
Property, Plant and Equipment [Line Items]    
Contract receivables $ 72,800,000 $ 79,400,000
Allowance for doubtful accounts against contracts receivable 0 0
Other current assets    
Property, Plant and Equipment [Line Items]    
Restricted cash, current $ 4,900,000 $ 4,800,000