Receivables, Net - Additional Information (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Back charges claims	$ 1,200,000	$ 1,100,000	$ 300,000
Total Gross Receivables	330,297,000	479,943,000	351,565,000
Uncollectible Receivables [Member] | Retentions [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Gross Receivables	$ 0	$ 0	$ 0