Restructuring - Changes in Restructuring Liability (Footnote) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2019	Sep. 30, 2019	Jan. 01, 2019
Restructuring Cost and Reserve [Line Items]
Reclassification of liabilities as a reduction of the ROU Asset capitalized upon adoption		$ (10.9)
Impairment of right-of-use	$ 24.8
Operating lease right-of-use assets		464.6
Accounting Standards Update 2016-02
Restructuring Cost and Reserve [Line Items]
Operating lease right-of-use assets			$ 518.0
Real Estate
Restructuring Cost and Reserve [Line Items]
Impairment of right-of-use		24.8
Real Estate | Level 3
Restructuring Cost and Reserve [Line Items]
Operating lease right-of-use assets		17.7
Contract Termination Costs
Restructuring Cost and Reserve [Line Items]
Reclassification of liabilities as a reduction of the ROU Asset capitalized upon adoption		(10.9)
Contract Termination Costs | Real Estate
Restructuring Cost and Reserve [Line Items]
Non-cash acceleration of amortization		4.1
Contract Termination Costs | Real Estate | Accounting Standards Update 2016-02
Restructuring Cost and Reserve [Line Items]
Reclassification of liabilities as a reduction of the ROU Asset capitalized upon adoption		$ 10.9