Contract Assets and Liabilities (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Contract Assets and Liabilities [Abstract]
Retainage receivable estimated by management to be collected beyond one year, percentage			39.00%
Capitalized contract costs were amortized and recognized as expense	$ 8.5	$ 4.0	$ 22.8	$ 12.2
Retainage payable estimated by management to be remitted beyond one year, percentage			30.00%
Contract with Customer, Liability, Revenue Recognized	$ 322.8	$ 251.4	$ 437.1	$ 341.2