Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities [Line Items]
Provision for credit losses	$ 1,900	$ 400	$ 14,213	$ 1,326
Contract liabilities	368,184		368,184		$ 206,180
Contract with customer liability, deferred revenue current	349,100		349,100		$ 184,100
Deferred revenue, revenue recognized	10,300		139,600
Non-recourse financing agreement, discount charge	(13,553)	(19,297)	(45,365)	(58,178)
Receivables, Non-Recourse Arrangement [Member]
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities [Line Items]
Non-recourse financing agreement, discount charge	$ (900)	$ (2,400)	$ (4,100)	$ (8,100)
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%