Accounting Changes and Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease ROU assets	$ 518.4
Operating leases	525.4
Finance lease ROU assets	557.4
Finance lease liabilities	631.5
Decrease to accumulated deficit	$ (5,164.0)		$ (5,172.2)
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease ROU assets		$ 545.1
Operating leases		558.1
Finance lease ROU assets		26.2
Finance lease liabilities		26.2
Decrease to accumulated deficit		1.2
Net reduction in ROU assets		$ 14.2