Income Tax (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets Income Tax Credits And Adjustments Subject To Expiration	$ 65,100
Valuation Allowance Related To Tax Cuts And Jobs Act Of 2017	58,900
Foreign Tax Credits Impact On Uncertain Tax Liabilities	57,000
Foreign Currency Translation Adjustment On Valuation Allowance	10,600
Reclassifications With Other Deferred Tax Assets On Valuation Allowance	(5,600)
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	25,900	$ 21,300
Cash paid for income taxes	48,700	68,000	$ 178,400
Tax Adjustments, Settlements, and Unusual Provisions	(1,033,755)	0	0
Deferred Tax Assets, Valuation Allowance	226,884	133,354
Proceeds from Income Tax Refunds	11,600	6,900	136,800
Deferred Tax Liability Not Recognized, Amount of Unrecognized Deferred Tax Liability	1,442,900	1,147,200
Tax Credit Carryforward, Valuation Allowance	65,100
Operating Loss Carryforwards	2,715,800	1,353,600
Income Tax Credits and Adjustments	152,000	100,900
Unrecognized Tax Benefits	321,224	297,290	296,213	$ 274,661
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	10,900
Unrecognized Tax Benefits, Interest on Income Taxes Expense	(5,000)	(8,400)	$ 8,200
Income Tax Examination, Penalties Expense		300
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	15,100	$ 20,400
Tax Year 2029 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	181,200
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	181,200
Tax Year 2030 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	451,400
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	451,400
Tax Year 2032 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	1,557,100
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	1,557,100
TaxYear20342036 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	48,000
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	48,000
Foreign Tax Authority [Member] | Australian Taxation Office [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	20,100
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	3,300
Foreign Tax Authority [Member] | Revenue Commissioners, Ireland [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 29,900