Income Taxes Income Taxes (Textual) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Provisional decrease to deferred tax assets and liabilities		$ 34,700,000
Adjustment to valuation allowance		34,700,000
Provisional amount of additional U.S. taxable income		8,400,000
Valuation allowance	$ 78,366,000	61,403,000	$ 78,366,000
Release of tax valuation allowance		17,000,000
Net operating loss carryforwards, federal		219,000,000
Net operating loss carryforwards, state		37,700,000
Decrease in foreign tax			$ 600,000	$ 700,000
Benefit of the tax holiday on net income per share (diluted)			$ 0.02	$ 0.02
Deferred tax liability, undistributed foreign earnings	4,879,000	4,879,000	$ 4,879,000
Unremitted earnings of a foreign subsidiary no longer considered indefinitely reinvested		97,600,000
Foreign taxes on unremitted earnings	1,200,000	0	1,204,000	$ 2,085,000
Unremitted earnings from foreign subsidiaries		11,800,000.0
Deferred tax assets included in non-current assets	$ 400,000	400,000	400,000
Unrecognized tax benefits, reduction in deferred tax assets		16,000,000
Unrecognized tax benefits, reduction to valuation allowance related to reduction in deferred tax assets		16,000,000
Interest and penalties		29,000	$ 148,000	$ 119,000
Federal
Income Taxes [Line Items]
Tax credit carryforwards, research and development		7,000,000
State
Income Taxes [Line Items]
Tax credit carryforwards, research and development		$ 9,000,000