Taxation - Summary of valuation allowance (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Valuation Allowance [Line Items]
Valuation allowance	$ 367,366	$ 276,301
Ireland
Valuation Allowance [Line Items]
Valuation allowance	96,642	93,396
United States
Valuation Allowance [Line Items]
Valuation allowance	92,999	106,624
United Kingdom
Valuation Allowance [Line Items]
Valuation allowance	32,528	46,732
Switzerland
Valuation Allowance [Line Items]
Valuation allowance	15,025	7,818
Other
Valuation Allowance [Line Items]
Valuation allowance	$ 130,172	$ 21,731