Segmental Reporting (Revenues by Geographic Location) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended										12 Months Ended
	Dec. 31, 2011		Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010		Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 1,142.2		$ 1,086.1	$ 1,062.9	$ 972.7	$ 931.2		$ 874.3	$ 849.4	$ 816.2	$ 4,263.4		$ 3,471.1		$ 3,007.7
Long-lived assets	933.7	[1]				857.4	[1]				933.7	[1]	857.4	[1]	680.6	[2]
Ireland
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues											21.1		21.1		19.5
Long-lived assets	2.9					0					2.9		0
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues											219.9		203.9		163.9
Long-lived assets	73.7					70.9					73.7		70.9
North America
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues											2,867.1		2,333.1		2,141.3
Long-lived assets	841.0					777.8					841.0		777.8
Rest of World
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues											1,155.3		913.0		683.0
Long-lived assets	$ 16.1					$ 8.7					$ 16.1		$ 8.7

[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 tax assets, investments, income tax receivable and financial instruments).