Revenue and Contract Balances - Schedule of Contract Balances (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jan. 01, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Accounts receivable	$ 49.2		$ 43.6
Contracts retention	7.6		8.6
Allowance for credit losses on accounts receivable and retention	(4.1)	$ (0.3)	(0.6)
Accounts receivable and retention, net	52.7		51.6
Costs and estimated earnings in excess of billings on uncompleted contracts	5.0		10.0
Billings in excess of costs and estimated earnings on uncompleted contracts	9.0		7.9
Variable consideration	62.0		62.0
Deferred revenue	$ 6.0		$ 5.6