Taxation (Pretax Income from Continuing Operations and Provision for Income Taxes) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Components of pre tax income from continuing operations
Income before income taxes and equity in earnings of equity method investees	$ 911.4	$ 1,090.1	$ 769.3
Current income taxes:
Other, current	29.0	40.0	25.9
Total current taxes	226.5	240.3	208.9
Deferred taxes:
Other, deferred	(10.0)	(29.6)	(10.3)
Total deferred taxes	(59.5)	(12.7)	(26.2)
Total income taxes	167.0	227.6	182.7
Republic of Ireland
Current income taxes:
Current domestic tax expense (benefit)	0	(1.8)	0
US federal tax
Current income taxes:
Current foreign tax expense (benefit)	186.5	193.1	176.4
Deferred taxes:
Deferred foreign tax expense (benefit)	(53.0)	22.5	(6.0)
US state and local taxes
Current income taxes:
Current foreign tax expense (benefit)	11.0	9.0	6.6
Deferred taxes:
Deferred foreign tax expense (benefit)	(9.5)	(4.6)	(9.8)
UK corporation tax
Deferred taxes:
Deferred foreign tax expense (benefit)	13.0	(1.0)	(0.1)
Ireland
Components of pre tax income from continuing operations
Republic of Ireland	(74.7)	(65.9)	(170.0)
United Kingdom
Components of pre tax income from continuing operations
Pre-tax income from continuing operations, foreign	30.7	45.3	35.4
United States
Components of pre tax income from continuing operations
Pre-tax income from continuing operations, foreign	587.4	747.6	745.5
Other jurisdictions
Components of pre tax income from continuing operations
Pre-tax income from continuing operations, foreign	$ 368.0	$ 363.1	$ 158.4