Receivables, net (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	$ 230,454	$ 207,869
Less: Allowance for doubtful accounts	(1,823)	(2,068)
Receivables, net	228,631	205,801
Trade receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	198,358	178,698
Amounts billed but not yet paid under retainage provisions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	3,711	3,093
Other receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	$ 28,385	$ 26,078