Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Costs in excess of billings	$ 20,607	$ 22,634	$ 16,532
Contract with customer liability	(17,311)	(12,028)
Billings in excess of cost
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with customer liability	(47,598)	(17,857)	(12,779)
Revenue recognized	17,371	10,097
Unearned revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with customer liability	(17,311)	(12,028)	$ (3,336)
Revenue recognized	$ 11,092	$ 2,988