Income Taxes (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019	Dec. 31, 2018 USD ($)
Operating Loss Carryforwards [Line Items]
Tax benefit from revalue of deferred tax liabilities			$ 1,524
Adjustment to valuation allowance			$ 1,524
Deferred income tax assets	$ 67,025
Net operating loss carryforwards	417,802
Loss carryforwards for U.S. federal income tax purposes	223,724
Loss carryforwards for U.S. state income tax purposes	155,366
Loss carryforwards for foreign income tax purposes	38,713
Unremitted earnings	189,699
Unrecognized deferred tax liability	7,114
Unrecognized tax benefits, period decrease	788
Unrecognized tax benefits, period increase	11,223
Unrecognized tax benefits that would impact effective tax rate	$ 15,380
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Difference in effective rate due to Tax Act (as a percentage)	0.253	0.280	0.256
Research and experimentation tax credit carryforwards	$ 6,359
Foreign tax credits	6,629
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Research and experimentation tax credit carryforwards	4,037
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Research and experimentation tax credit carryforwards	1,059
Other State Income Tax
Operating Loss Carryforwards [Line Items]
Other tax credits	$ 729