Condensed Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 41,469	$ 61,367
Short-term investments	28,393	11,899
Accounts receivable, net of allowances of $498 and $381, at March 31, 2013 and December 31, 2012, respectively	15,111	22,389
Inventory	25,129	25,080
Deferred cost of revenue	759	967
Financing commitment asset (Note 8)	6,947	7,608
Prepaids and other current assets	2,453	1,972
Total current assets	120,261	131,282
Long-term investments	1,165
Cost method investment (Note 4)	4,181	4,181
Property and equipment, net	23,414	22,996
Intangible assets, net	5,229	5,657
Other assets	2,786	2,786
Total assets	157,036	166,902
Current liabilities:
Accounts payable	1,509	2,267
Accrued compensation and employee benefits	2,505	4,298
Other accrued liabilities	7,702	8,727
Deferred revenue	8,622	9,973
Total current liabilities	20,338	25,265
Deferred revenue, non-current	752	800
Total liabilities	21,090	26,065
Commitments and contingencies (Note 7)
Stockholders' equity:
Preferred stock, $0.001 par value; 27,000,000 authorized; 0 shares issued and outstanding as of March 31, 2013 and December 31, 2012
Common stock, $0.001 par value; 135,000,000 authorized; 46,839,896 and 46,601,252 shares issued and outstanding as of March 31, 2013 and December 31, 2012, respectively	47	47
Additional paid-in capital	367,114	362,364
Accumulated deficit	(231,196)	(221,576)
Accumulated other comprehensive gain (loss)	(19)	2
Total stockholders' equity	135,946	140,837
Total liabilities and stockholders' equity	$ 157,036	$ 166,902