Revenue by Geographic Segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues, total	$ 877.4	$ 1,020.1	$ 2,727.1	$ 2,868.5
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	344.0	452.8	1,094.3	1,177.0
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	114.2	100.8	325.5	299.7
Other Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 419.2	$ 466.5	$ 1,307.3	$ 1,391.8