CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 215,036	$ 132,526
Short-term investments	197,406	250,928
Accounts receivable, net	39,766	38,000
Inventories, net	47,028	48,569
Prepaid expenses and other current assets	9,437	7,946
Total current assets	508,673	477,969
Long-term investments	0	25,871
Fixed assets, net	107,051	108,670
Operating Lease, Right-of-Use Asset	26,686	0
Goodwill	62,040	62,040
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties, Amount	14,146	14,146
Other assets	560	657
Total assets	719,156	689,353
Current liabilities:
Accounts payable	13,369	14,368
Accrued expenses	39,696	45,865
Operating Lease, Liability, Current	5,583	0
Convertible senior notes	0	338
Income taxes payable	343	90
Total current liabilities	58,991	60,661
Convertible senior notes	294,356	290,592
Operating Lease, Liability, Noncurrent	29,297	0
Other liabilities	8,993	16,874
Total liabilities	391,637	368,127
Commitments and contingencies (Note 14)
Stockholders’ equity:
Preferred stock, par value $0.001; 5,000,000 shares authorized; none issued and outstanding at March 31, 2019 and December 31, 2018	0	0
Common stock, par value $0.001; 250,000,000 shares authorized; 41,288,703 shares issued and outstanding at March 31, 2019; 41,222,799 shares issued and outstanding at December 31, 2018	41	41
Additional paid-in capital	718,449	709,691
Accumulated deficit	(391,153)	(388,226)
Accumulated other comprehensive income (loss)	182	(280)
Total stockholders’ equity	327,519	321,226
Total liabilities and stockholders’ equity	$ 719,156	$ 689,353