Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 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			$ 1,300	$ 3,500
Billings in excess of costs and earnings	$ 156,929		156,929		$ 227,056
Revenue recognition, BIEC, revenue recognized	24,100	$ 25,400	189,000	125,600
Contract liabilities	183,500		183,500		$ 231,600
Interest expense, net	19,297	22,330	58,178	60,183
Accounts Receivable Financing Arrangements [Member]
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities [Line Items]
Interest expense, net	$ 2,400	$ 3,200	$ 8,100	$ 8,200
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%