Income Taxes (Summary Of Tax Loss And Tax Credit Carryforwards) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Tax Credit Carryforward [Line Items]
Deferred tax asset on tax carryforwards	$ 105,600	$ 113,800
Valuation Allowance, Amount	(145,900)	$ (141,000)
Tax Loss and Credit Carryforwards [Member]
Tax Credit Carryforward [Line Items]
Deferred tax asset on tax carryforwards	105,600
Valuation Allowance, Amount	(98,700)
Net deferred tax asset on tax carryforwards	6,900
U.S. Federal Tax Credits [Member]
Tax Credit Carryforward [Line Items]
2016-2020	17,900
After 2020	3,500
Indefinite	0
Total tax carryforwards	21,400
Deferred tax asset on tax carryforwards	21,400
Valuation Allowance, Amount	(21,400)
Net deferred tax asset on tax carryforwards	0
U.S Federal Tax Losses [Member]
Tax Credit Carryforward [Line Items]
2016-2020	200
After 2020	1,800
Total tax carryforwards	2,000
Deferred tax asset on tax carryforwards	700
Valuation Allowance, Amount	(400)
Net deferred tax asset on tax carryforwards	300
U.S. State Tax Credits [Member]
Tax Credit Carryforward [Line Items]
2016-2020	4,000
After 2020	2,400
Indefinite	19,600
Total tax carryforwards	26,000
Deferred tax asset on tax carryforwards	16,900
Valuation Allowance, Amount	(16,300)
Net deferred tax asset on tax carryforwards	600
U.S. State Tax Losses [Member]
Tax Credit Carryforward [Line Items]
2016-2020	27,300
After 2020	795,900
Total tax carryforwards	823,200
Deferred tax asset on tax carryforwards	37,700
Valuation Allowance, Amount	(36,900)
Net deferred tax asset on tax carryforwards	800
Non-U.S. Tax Losses [Member]
Tax Credit Carryforward [Line Items]
2016-2020	16,300
After 2020	3,000
Indefinite	98,600
Total tax carryforwards	117,900
Deferred tax asset on tax carryforwards	28,900
Valuation Allowance, Amount	(23,700)
Net deferred tax asset on tax carryforwards	$ 5,200