Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 335,592	$ 35,857
Short-term investments	132,220	121,573
Accounts receivable, trade, net	47,758	55,859
Accounts receivable, other	2,298	1,685
Inventories, current	24,459	22,134
Prepaid expenses and other current assets	3,910	3,762
Total current assets	546,237	240,870
Inventories, non-current	48,566	49,697
Property and equipment, net	33,734	29,220
Long-term investments	0	1,442
Other assets	14,071	6,163
Total assets	642,608	327,392
Current liabilities:
Accounts payable	3,311	3,565
Accrued expenses	83,404	80,740
Deferred revenue, current portion	4,483	11,835
Deferred rent, current portion	2,176	936
Total current liabilities	93,374	97,076
Senior Convertible Notes	285,392	0
Deferred revenue, long-term portion	25,780	26,288
Deferred rent, long-term portion	6,104	4,140
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.01 par value per share, 5,000,000 shares authorized, no shares issued or outstanding
Common stock, $0.01 par value per share; authorized 120,000,000 shares; issued 49,449,438 and 49,419,104 shares at March 31, 2013 and December 31, 2012, respectively	494	494
Additional paid-in capital	565,449	525,354
Accumulated deficit	(330,275)	(322,115)
Treasury stock at cost: 143,410 and 136,405 shares at March 31, 2013 and December 31, 2012, respectively	(3,462)	(3,337)
Accumulated other comprehensive loss	(248)	(508)
Total stockholders' equity	231,958	199,888
Total liabilities and stockholders' equity	$ 642,608	$ 327,392