Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Capitalized Contract Cost [Line Items]
Costs in excess of billings	$ 21,834		$ 20,607
Amounts included in billings in excess of cost at the beginning of the period	29,221	$ 9,697
Amounts included in unearned revenue at the beginning of the period	9,619	$ 4,661
Billings in excess of cost
Capitalized Contract Cost [Line Items]
Contract with customer liability	(34,567)		(47,598)
Unearned revenue
Capitalized Contract Cost [Line Items]
Contract with customer liability	$ (19,388)		$ (17,311)