Receivables, net (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	$ 273,394	$ 207,869
Less: Allowance for doubtful accounts	(1,793)	(2,068)
Receivables, net	271,601	205,801
Trade receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	237,250	178,698
Amounts billed but not yet paid under retainage provisions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	3,644	3,093
Other receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	$ 32,500	$ 26,078