Deferred Contract Costs - Summary of Deferred Contract Costs (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Capitalized Contract Cost [Line Items]
Total deferred contract costs	$ 22.9	$ 20.2
Prepaid expenses and other current assets
Capitalized Contract Cost [Line Items]
Total deferred contract costs	3.4	2.8
Other assets
Capitalized Contract Cost [Line Items]
Total deferred contract costs	$ 19.5	$ 17.4