CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 116,871	$ 54,126
Short-term investments	254,450	257,221
Accounts receivable, net	35,641	31,658
Inventories, net	42,053	41,411
Prepaid expenses and other current assets	6,039	6,694
Total current assets	455,054	391,110
Long-term investments	1,601	60,047
Fixed assets, net	111,276	107,046
Goodwill	59,912	55,197
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	14,146	14,146
Other assets	692	825
Total assets	642,681	628,371
Current liabilities:
Accounts payable	14,260	14,658
Accrued expenses and current portion of deferred revenue	38,434	41,159
Convertible senior notes	330	324
Income taxes payable	0	76
Total current liabilities	53,024	56,217
Convertible senior notes	283,258	276,173
Other liabilities	15,886	16,498
Total liabilities	352,168	348,888
Commitments and contingencies (Note 13)
Stockholders’ equity:
Preferred stock, par value $0.001; 5,000,000 shares authorized; none issued and outstanding at June 30, 2018 and December 31, 2017	0	0
Common stock, par value $0.001; 250,000,000 shares authorized; 40,954,969 shares issued and outstanding at June 30, 2018; 40,668,877 shares issued and outstanding at December 31, 2017	41	41
Additional paid-in capital	686,888	669,032
Accumulated deficit	(395,871)	(389,136)
Accumulated other comprehensive loss	(545)	(454)
Total stockholders’ equity	290,513	279,483
Total liabilities and stockholders’ equity	$ 642,681	$ 628,371

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.