Revenue by Geographic Segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 882.5	$ 792.1	$ 2,450.6	$ 2,460.6
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	377.3	337.6	997.0	1,008.7
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	104.6	99.0	327.5	296.4
Other International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 400.6	$ 355.5	$ 1,126.1	$ 1,155.5