Revenue Contract Balances (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Contract assets, net of allowances of $1.0 in 2020 and $2.5 in 2019	$ 1,267.6	$ 1,520.0
Contract with Customer, Asset, Net, Current, Increase (Decrease)	$ (252.4)
Contract with Customer, Asset, Net, Current, Increase (Decrease), Percent	(16.60%)
Contract liabilities	$ 4,736.1	4,585.1
Contract with Customer Liability, Current, Increase (Decrease)	$ 151.0
Contract with Customer Liability, Current, Increase (Decrease), Percent	3.30%
Contract assets (liabilities), Current, Net	$ (3,468.5)	(3,065.1)
Contract assets (liabilities), Current, Net, Increase (Decrease)	$ (403.4)
Costs in Excess of Billings (Billings in Excess of Cost), Current, Net, Increase (Decrease), Percent	(13.20%)
Contract with Customer, Liability, Revenue Recognized	$ 1,267.5	2,414.0
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 470.8	$ 1,176.5