Schedule II - Valuation And Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Provision for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the Beginning of the Period	$ 4,280	$ 0	$ 0
Charged to Revenue, Cost or Expense	0	4,280	0
Deduction	1,680	0	0
Balance at the End of the Period	2,600	4,280	0
Reserve for losses on uncompleted contracts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the Beginning of the Period	22,770	0	0
Charged to Revenue, Cost or Expense	2,455	22,770	0
Deduction	14,300	0	0
Balance at the End of the Period	$ 10,925	$ 22,770	$ 0