Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Income Taxes [Abstract]
Federal net operating loss carryforward	$ 138,294	$ 133,454
State net operating loss carryforward	53,890	53,350
Asset impairment charges	27,871	31,137
Accrued liabilities	26,298	29,600
Stock-based compensation expense	26,946	26,771
Alternative minimum tax and other tax credit carryforwards	10,296	10,296
Inventory, additional costs capitalized for tax	3,466	3,466
Unrealized loss on marketable securities	266	2,787
Other	1,541	1,522
Total deferred tax assets	288,868	292,383
Valuation allowance	(277,185)	(281,178)
Total deferred tax assets, net of valuation allowance	11,683	11,205
Deferred revenue	5,959	5,589
Property, equipment and other assets	804	706
Accrued liabilities	32	32
Inventory, additional costs capitalized for financial statement	538	542
Other, net	4,350	4,336
Total deferred tax liabilities	11,683	11,205
Net deferred tax asset