Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities [Line Items]
Retainage, expected collection period (in years)			1 year
Provisions for doubtful accounts			$ 900	$ 1,400
Billings in excess of costs and earnings	$ 200,576		200,576		$ 227,056
Revenue recognition, BIEC, revenue recognized	41,200	$ 15,000	164,900	99,800
Contract liabilities	221,500		221,500		$ 231,600
Interest expense, net	16,623	20,795	38,881	37,854
Accounts Receivable Financing Arrangements [Member]
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities [Line Items]
Interest expense, net	$ 2,800	$ 3,100	$ 5,700	$ 5,000
Minimum [Member]
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities [Line Items]
Retainage, percentage of contract billings			5.00%
Maximum [Member]
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities [Line Items]
Retainage, percentage of contract billings			10.00%