Segment Information - Revenue, Properties and Outsourcing Assets by Geographic Segment (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 683.3	$ 739.2	$ 2,099.0	$ 2,225.2
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	327.1	359.9	1,006.4	1,085.8
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	72.3	92.6	263.6	264.1
Other foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 283.9	$ 286.7	$ 829.0	$ 875.3