Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Capitalized Contract Cost [Line Items]
Costs in excess of billings	$ 35,432		$ 20,607
Amounts included in billings in excess of cost at the beginning of the period	44,723	$ 14,137
Amounts included in unearned revenue at the beginning of the period	13,614	$ 11,052
Billings in excess of cost
Capitalized Contract Cost [Line Items]
Contract with customer liability	(31,267)		(47,598)
Unearned revenue
Capitalized Contract Cost [Line Items]
Contract with customer liability	$ (18,951)		$ (17,311)