Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit)	$ 87,000
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Change in Tax Rate, Deferred Tax Asset, Provisional Income Tax Expense	75,000
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Transition Tax for Accumulated Foreign Earnings, Provisional Liability	12,000	$ 12,000
Tax expense/(benefit) related to changes in pension and post-retirement plan assets and benefit obligations	3,500	3,500	$ (8,400)	$ 4,600
Unrealized tax asset on related tax loss		99,700	96,500
Valuation allowance against U.S. and non-U.S. deferred tax assets		23,300	51,700
Total valuation allowance	123,000	123,000	148,200
Increase in total amount of unrecognized tax benefits that would impact effective tax rate	49,200	49,200	47,600	46,600
Interest expense and penalties, related to unrecognized tax benefits		300	400	$ 1,100
Unrecognized tax benefits, income tax penalties and interest accrued	6,500	6,500	$ 6,200
Change in unrecognized tax benefits is reasonably possible, amount of unrecorded benefit	$ 11,400	$ 11,400