Taxation - Tax rates by jurisdiction (Details)	12 Months Ended
	Dec. 31, 2013
Bermuda
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	0.00%
United States
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	35.00%
United Kingdom
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	23.25%
Germany
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	15.00%
France
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	38.00%
Active income | Ireland
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	12.50%	[1]
Active income | Switzerland
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	7.83%	[2]
Passive income | Ireland
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	25.00%	[1]
Passive income | Switzerland
Income Tax Disclosure [Line Items]
Applicable statutory tax rate, by jurisdiction	21.20%	[2]

[1] The different applicable statutory taxation rates in Ireland relate to entities classified as trading or non-trading companies.

[2] The different applicable statutory taxation rates in Switzerland relate to entities classified as trading or holding companies.