Revenue Recognition - Deferred Revenue (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue Recognition [Abstract]
Balance at beginning of period	$ 116.6	$ 85.6	$ 107.1	$ 81.6
New contracts sold	18.0	13.6	38.6	26.8
Less: reductions for revenue recognized	(10.9)	(9.4)	(22.0)	(18.6)
Balance at end of period	$ 123.7	$ 89.8	$ 123.7	$ 89.8

Amount of deferred revenue recognized for transactions arising during the current reporting period. Deferred revenue is a liability as of the balance sheet date related to a revenue producing activity for which revenue has not yet been recognized. Generally, an Entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

No definition available.

Name:	us-gaap_DeferredRevenueAdditions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration