Income Tax Examination [Abstract]

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[Line Items] for Income Tax [Table]

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible alternative minimum tax credit carryforwards.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Alternative Minimum Tax
-URI http://asc.fasb.org/extlink&oid=6504908

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-Name Accounting Standards Codification
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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible research tax credit carryforwards.

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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The amount of estimated penalties and interest accrued as of the balance sheet date arising from income tax examinations.

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Carrying amount as of the balance sheet date of income taxes previously overpaid to tax authorities (such as U.S. Federal, state and local tax authorities) representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes. Also called income tax refund receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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-Number 210
-Section 03
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-Subparagraph c
-Article 7

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

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Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

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Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax [Line Items]
Income tax receivables	$ 100	$ 100
Valuation Allowance [Abstract]
Change in valuation allowance	24,400	20,600
Valuation allowance	173,872	149,474
Alternative minimum tax credit carryforward	3,626	3,626
Research and development tax credit carryforwards	24,442	22,979
Income Tax Uncertainties [Abstract]
Unrecognized tax benefits	320	3,541	$ 4,505	$ 3,978
Income Tax Examination [Abstract]
Accrued interest and penalties related to uncertain tax positions	0	0
Internal Revenue Service (IRS)
Valuation Allowance [Abstract]
Operating loss carryforwards	$ 241,200	$ 190,100