Revenue - Contract Balances (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Contract assets	$ 1,503.0		$ 1,503.0		$ 1,295.0
Contract liabilities	4,122.5		4,122.5		4,085.1
Net contract assets (liabilities)	(2,619.5)		(2,619.5)		$ (2,790.1)
Contract assets, increase (decrease)			$ 208.0
Contract with Customer, Asset, Net, Current, Increase (Decrease), Percent			16.10%
Contract (liabilities), (increase) decrease			$ (37.4)
Contract with Customer Liability, Current, Increase (Decrease), Percent			0.90%
Net contract assets (liabilities), increase (decrease)			$ 170.6
Contract Assets (Liabilities), Current, Net, Increase (Decrease), Percent			6.10%
Contract with Customer, Liability, Revenue Recognized	503.6	$ 678.1	$ 1,984.4	$ 2,115.8
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 281.7	$ 182.5	$ 775.1	$ 489.2