Taxation - Narrative (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Line Items]
U.S. Tax Cuts and Jobs Act of 2017, net deferred tax asset revaluation		$ 100,500
Deferred tax asset, per balance sheet		332,024	$ 310,542
Deferred tax liability, per balance sheet		57,574	77,271
Valuation allowance		338,556	367,366
Increase (decrease) in valuation allowance, amount		(28,800)
Net operating loss carryforwards, amount		1,854,654
Capital loss carryforwards, tax effected		53,304	71,651
Capital loss carryforwards available		281,760
Unrecognized tax benefits		64,960	97,780	$ 80,590	$ 37,190
Accrued interest and penalties		3,800	900	$ 400
United States
Income Tax Disclosure [Line Items]
Valuation allowance		53,761	92,999
Net operating loss carryforwards, amount	[1]	305,771
Capital loss carryforwards available		144,691
Alternative minimum tax credit carryforwards		31,700
Foreign tax carryforwards		3,000
Research tax carryforwards		3,100
United States | Carryforwards Expiring in Next Fiscal Year [Member]
Income Tax Disclosure [Line Items]
Capital loss carryforwards available		41,200
United States | Expiring in future years
Income Tax Disclosure [Line Items]
Capital loss carryforwards available		103,500
United States | Deferred tax asset restricted under Internal Revenue Code Section 382
Income Tax Disclosure [Line Items]
Net operating loss carryforwards, amount		47,000
Ireland
Income Tax Disclosure [Line Items]
Valuation allowance		86,647	96,642
Net operating loss carryforwards, amount	[2]	430,685
Capital loss carryforwards available		122,142
United Kingdom
Income Tax Disclosure [Line Items]
Valuation allowance		28,328	32,528
Net operating loss carryforwards, amount		228,444
Capital loss carryforwards available	[3]	14,927
Foreign tax carryforwards		15,500
Switzerland
Income Tax Disclosure [Line Items]
Valuation allowance		20,935	15,025
Net operating loss carryforwards, amount	[4]	181,789
Switzerland | Carryforwards Expiring In 2019 [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards, amount		31,800
Switzerland | Expiring in future years
Income Tax Disclosure [Line Items]
Net operating loss carryforwards, amount		146,000
Switzerland | Carryforwards Expiring in Next Fiscal Year [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards, amount		4,000
Germany
Income Tax Disclosure [Line Items]
Valuation allowance		32,566	9,562
Net operating loss carryforwards, amount		177,587
France
Income Tax Disclosure [Line Items]
Valuation allowance		28,656	$ 23,523
Net operating loss carryforwards, amount		$ 110,615

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

[2] 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.

[3] oss carryforwards of $41.2 million will expire at the end of 2018 with another $103.5 million expiring in future years through 2021.

[4] 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.