Income Taxes Income Taxes (Textual) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
Valuation allowance	$ 64,199,000	$ 68,093,000	$ 64,199,000
Increase (decrease) in valuation allowance		(3,900,000)
Operating loss carryforwards, federal		152,900,000
Operating loss carryforwards, state		61,200,000
Tax credit carryforwards research and development and other, federal		6,100,000
Tax credit carryforwards research and development and other, state		7,700,000
Excess tax benefits from employee stock purchase plan		3,500,000	3,600,000
Decrease in foreign tax		$ 672,000	$ 665,000
Benefit of the tax holiday on net income per share (diluted)		$ 0.02	$ 0.02
Foreign taxes on unremitted earnings	1,590,000	$ 2,085,000		$ 0
Unremitted earnings of a foreign subsidiary no longer considered indefinitely reinvested	31,800,000	41,700,000	$ 31,800,000
Unremitted earnings from foreign subsidiaries		10,200,000
Deferred tax assets included in non-current assets	$ 460,000	491,000	460,000
Total unrecognized tax benefits		13,800,000
Interest and penalties		119,000	$ 34,000	$ 126,000
Germany
Income Taxes [Line Items]
Increase (decrease) in valuation allowance		316,000
Deferred Tax Asset, Stock Option Deductions
Income Taxes [Line Items]
Valuation allowance		$ 15,500,000