Contract Assets And Liabilities (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Contract with Customer, Contract Asset, Contract Liability, and Receivable [Abstract]
Retainage receivable estimated by management to be collected beyond one year, percentage	38.00%
Costs and estimated earnings in excess of billings estimated to be collected	$ 756.2
Capitalized contract costs were amortized and recognized as expense	$ 46.7	$ 33.8	$ 16.3
Retainage payable estimated by management to be remitted beyond one year, percentage	38.00%
Revenue recognized	$ 690.7	$ 479.6	$ 382.7