Revenue - Contract Balances (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Accounts receivable, net	$ 313.7	$ 269.3	$ 270.8
Short-term contract assets	1.4	1.0	1.3
Long-term contract assets	3.8	2.8	2.6
Short-term deferred revenue	467.2	467.5	529.1
Long-term deferred revenue	$ 16.3	$ 7.8	$ 7.3