Income Taxes Income Taxes (Textual) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Provisional decrease to deferred tax assets and liabilities	$ 34,700
Adjustment to valuation allowance	34,700
Provisional amount of additional U.S. taxable income	8,400
Valuation allowance	67,012	$ 61,403
Release of tax valuation allowance	5,600
Net operating loss carryforwards, federal	235,200
Net operating loss carryforwards, state	43,600
Deferred tax liability, undistributed foreign earnings	0	4,879
Deferred tax assets included in non-current assets	300	400
Unrecognized tax benefits, reduction in deferred tax assets	17,500
Unrecognized tax benefits, reduction to valuation allowance related to reduction in deferred tax assets	17,500
Interest and penalties	(27)	$ 29
Federal
Income Taxes [Line Items]
Tax credit carryforwards, research and development	7,700
State
Income Taxes [Line Items]
Tax credit carryforwards, research and development	$ 9,800