Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ 53,100
Tax Credit Carryforward [Line Items]
Valuation allowance	21,561	$ 30,953
Unrecognized tax benefits affecting effective tax rate	63,100
Interest and penalties associated with unrecognized tax benefits (Operations)	(2,800)
Interest and penalties associated with unrecognized tax benefits (Balance Sheet)	30,900
State and Local Jurisdiction
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	291,100
Deferred tax assets, operating loss and tax credit carryforwards	27,100
State and Local Jurisdiction | Wisconsin
Tax Credit Carryforward [Line Items]
Valuation allowance	4,500
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	100
State and Local Jurisdiction | Wisconsin Research And Development Credit | Wisconsin
Tax Credit Carryforward [Line Items]
Net capital loss carryforwards	11,300
Foreign Tax Authority
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	6,100
Deferred tax assets, operating loss and tax credit carryforwards	11,000
Operating loss carryforwards, valuation allowance	17,100
Operating loss carryforward, increase in valuation allowance	$ 9,200