Segmental Reporting (Revenues and Long-lived Assets by Geographic Location) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended										12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011		Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 1,201.2		$ 1,100.4	$ 1,207.8	$ 1,171.8	$ 1,142.2		$ 1,086.1	$ 1,062.9	$ 972.7	$ 4,681.2		$ 4,263.4		$ 3,471.1
Long-lived assets	957.2	[1]				933.7	[1]				957.2	[1]	933.7	[1]	857.4	[2]
Ireland
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues											20.6		21.1		21.1
Long-lived assets	5.2					2.9					5.2		2.9
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues											207.0		219.9		203.9
Long-lived assets	72.2					73.7					72.2		73.7
North America
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues											3,159.9		2,867.1		2,333.1
Long-lived assets	861.0					841.0					861.0		841.0
Rest of World
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues											1,293.7		1,155.3		913.0
Long-lived assets	$ 18.8					$ 16.1					$ 18.8		$ 16.1

[1] Long-lived assets comprise all non-current assets (excluding goodwill and other intangible assets, deferred contingent consideration assets, deferred tax assets, investments, income tax receivable and financial instruments).

[2] Long-lived assets comprise all non-current assets, (excluding goodwill and other intangible assets, deferred contingent consideration assets, deferred tax assets, investments, income tax receivable and financial instruments).