Guarantees (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Parent company guarantees on lease obligations	$ 824.5	$ 829.2
Parent company guarantees relating to credit facilities	349.1	308.8
Cash pooling guarantees	207.8	$ 182.2
Assets pledged as security for parent company guarantees	$ 0.0