Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ (1,500)	$ 53,100
Tax Credit Carryforward [Line Items]
Valuation allowance	21,868	$ 21,561
Unrecognized tax benefits affecting effective tax rate	53,700
Interest and penalties associated with unrecognized tax benefits (Operations)	3,200
Interest and penalties associated with unrecognized tax benefits (Balance Sheet)	27,700
State and Local Jurisdiction
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	270,400
Deferred tax assets, operating loss and tax credit carryforwards	25,900
State and Local Jurisdiction | Wisconsin
Tax Credit Carryforward [Line Items]
Valuation allowance	2,900
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	1,600
State and Local Jurisdiction | Wisconsin Research And Development Credit | Wisconsin
Tax Credit Carryforward [Line Items]
Net capital loss carryforwards	11,400
Foreign Tax Authority
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	8,900
Deferred tax assets, operating loss and tax credit carryforwards	10,000
Operating loss carryforwards, valuation allowance	18,900
Operating loss carryforward, increase in valuation allowance	$ 1,800