Property and Equipment - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Property, software and equipment depreciation, amortization expense	$ 401.2	$ 341.4	$ 307.7
Capitalization of stock-based compensation	34.8	28.9	$ 23.1
Disposal of property plant and equipment	208.0	174.6
Write off of internal-use software	4.9	$ 36.2
Net book value of internal-use software	$ 32.0