CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 35,029	$ 56,984
Short-term investments	114,992	101,981
Accounts receivable, net	25,901	25,855
Inventories, net	63,744	61,645
Prepaid expenses and other current assets	8,959	6,117
Total current assets	248,625	252,582
Long-term investments	13,470	13,462
Fixed assets, net	95,846	90,324
Goodwill	32,784	30,880
Intangibles, net	0	81
Other assets	481	406
Total assets	391,206	387,735
Current liabilities:
Accounts payable	10,484	8,739
Accrued expenses	29,067	35,375
Convertible senior notes	105,215	104,040
Current portion of deferred revenue	1,275	1,426
Income taxes payable	98	208
Total current liabilities	146,139	149,788
Deferred revenue	7,877	8,082
Other liabilities	11,020	11,473
Total liabilities	$ 165,036	$ 169,343
Commitments and contingencies
Stockholders’ equity:
Preferred stock, par value $0.001; 5,000,000 shares authorized; none issued and outstanding at March 31, 2016 and December 31, 2015	$ 0	$ 0
Common stock, par value $0.001, 250,000,000 shares authorized; 37,103,427 shares issued and outstanding at March 31, 2016; 36,848,319 shares issued and outstanding at December 31, 2015	37	37
Additional paid-in capital	538,227	526,696
Accumulated deficit	(312,143)	(308,289)
Accumulated other comprehensive income (loss)	49	(52)
Total stockholders’ equity	226,170	218,392
Total liabilities and stockholders’ equity	$ 391,206	$ 387,735