Income Taxes (Tax Effects of Temporary Differences That Give Rise to Deferred Tax Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Income Taxes Tax Effects Of Temporary Differences That Give Rise To Deferred Tax Assets Details
Net operating loss carryforward	$ 109,751	$ 132,101
Research credit carryforward	82,633	68,277
Capital loss carryforward	4,101	4,186
Non-recourse debt	26,060	27,769
Acquired intellectal property	26,344	29,452
Capitalization of inventory	11,021us-gaap_DeferredTaxAssetsInventory	9,429us-gaap_DeferredTaxAssetsInventory
Stock compensation expense	4,479	2,935
Accrued compensation	3,269	3,117
Other	697us-gaap_DeferredTaxAssetsOther	555us-gaap_DeferredTaxAssetsOther
Total gross deferred tax assets	268,355us-gaap_DeferredTaxAssetsGross	277,821us-gaap_DeferredTaxAssetsGross
Less valuation allowance	(268,355)	(277,821)
Deferred tax assets	0us-gaap_DeferredTaxAssetsNet	0us-gaap_DeferredTaxAssetsNet
Deferred tax liabilities	0us-gaap_DeferredTaxLiabilities	0us-gaap_DeferredTaxLiabilities
Net deferred tax asset (liability)	$ 0us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 0us-gaap_DeferredTaxAssetsLiabilitiesNet

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