Segment Information - Revenue, Properties and Outsourcing Assets by Geographic Segment (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 515.4	$ 554.5
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	215.6	191.4
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	64.5	95.3
Other foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 235.3	$ 267.8