Taxation - Summary of net operating loss carryforwards (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, amount		$ 1,854,654
Net operating loss		339,130	$ 323,716
Net operating loss carryforwards valuation allowance, amount		(231,937)
Net operating loss carryforwards, tax effected		107,193
Australia
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, amount		60,565
Net operating loss		18,169
Net operating loss carryforwards valuation allowance, amount		(18,166)
Net operating loss carryforwards, tax effected		3
Austria
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, amount		33,483
Net operating loss		8,371
Net operating loss carryforwards valuation allowance, amount		(837)
Net operating loss carryforwards, tax effected		7,534
France
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, amount		110,615
Net operating loss		28,904
Net operating loss carryforwards valuation allowance, amount		(28,657)
Net operating loss carryforwards, tax effected		247
Germany
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, amount		177,587
Net operating loss		49,764
Net operating loss carryforwards valuation allowance, amount		(32,566)
Net operating loss carryforwards, tax effected		17,198
Ireland
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, amount	[1]	430,685
Net operating loss	[1]	53,836
Net operating loss carryforwards valuation allowance, amount	[1]	(53,836)
Net operating loss carryforwards, tax effected	[1]	0
Spain
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, amount		103,822
Net operating loss		11,479
Net operating loss carryforwards valuation allowance, amount		(11,186)
Net operating loss carryforwards, tax effected		293
Switzerland
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, amount	[2]	181,789
Net operating loss	[2]	20,620
Net operating loss carryforwards valuation allowance, amount	[2]	(20,620)
Net operating loss carryforwards, tax effected	[2]	0
United Kingdom
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, amount		228,444
Net operating loss		42,612
Net operating loss carryforwards valuation allowance, amount		(31,913)
Net operating loss carryforwards, tax effected		10,699
United States
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, amount	[3]	305,771
Net operating loss	[3]	64,212
Net operating loss carryforwards valuation allowance, amount	[3]	(1,179)
Net operating loss carryforwards, tax effected	[3]	63,033
Other jurisdictions
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, amount		221,893
Net operating loss		41,163
Net operating loss carryforwards valuation allowance, amount		(32,977)
Net operating loss carryforwards, tax effected		$ 8,186
Minimum | Switzerland
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date		Jan. 01, 2018
Minimum | United States
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date		Jan. 01, 2033
Maximum | Switzerland
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date		Dec. 31, 2025
Maximum | United States
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date		Dec. 31, 2037

[1] These net operating loss carryforwards relate to a former Irish tax resident company which is in the process of withdrawing from Ireland. Any remaining unused loss carryforward, and the related valuation allowance, will be eliminated at the time of the receipt of tax clearance.

[2] osses of $4.0 million and $31.8 million will expire in 2018 and 2019, respectively, with the remaining $146.0 million expiring through 2025.

[3] pproximately $47.0 million of the net operating loss carryforwards is subject to restrictions on timing and utilization under §382 of the IRS Code.