Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Examination [Line Items]
Income tax (provision) benefit	$ (1,740)	$ (241)	$ 664	$ 415	$ (1,733)	$ (552)	$ 4,463	$ (1,171)	$ (902)	$ 1,007	$ (3,706)
Current tax expense related to foreign taxes									847	2,762	1,806
Income tax expense from permanent book and tax differences									8,900	15,200	19,700
Adjustment due to tax restructuring									11,200
Current income tax expense									892	2,720	1,687
Deferred tax provision (benefit)									10	(3,727)	2,019
Increase in valuation allowance										17,300	19,000
Income tax adjustments from impairment of goodwill										58,600
Deferred tax assets, valuation allowance	220,115				219,607				220,115	219,607	200,366
Liabilities for unrecognized tax benefit									700	1,600
Unrecognized tax benefits that would affect the effective tax rate	2,000				2,300				2,000	2,300	$ 2,500
Unrecognized tax benefits, accrued interest and penalties	100				$ 700				100	$ 700
Federal
Income Tax Examination [Line Items]
Operating loss carryforwards	578,500								578,500
State
Income Tax Examination [Line Items]
Operating loss carryforwards	1,360,700								1,360,700
Foreign
Income Tax Examination [Line Items]
Operating loss carryforwards	5,100								5,100
Research & development credit carryforward
Income Tax Examination [Line Items]
Tax credit carryforward	$ 3,200								$ 3,200