Revenue - Contract Balances (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Contract assets	$ 1,612.4		$ 1,612.4		$ 1,295.0
Contract liabilities	4,354.6		4,354.6		4,085.1
Net contract assets (liabilities)	(2,742.2)		(2,742.2)		$ (2,790.1)
Contract assets, increase (decrease)			$ 317.4
Contract with Customer, Asset, Net, Current, Increase (Decrease), Percent			24.50%
Contract (liabilities), (increase) decrease			$ (269.5)
Contract with Customer Liability, Current, Increase (Decrease), Percent			6.60%
Net contract assets (liabilities), increase (decrease)			$ 47.9
Contract Assets (Liabilities), Current, Net, Increase (Decrease), Percent			1.70%
Contract with Customer, Liability, Revenue Recognized	1,147.1	$ 601.4	$ 2,014.3	$ 1,437.7
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 325.7	$ 136.4	$ 493.4	$ 306.8