Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 732,190	$ 370,829
Short-term investments	612,018	803,083
Accounts receivable	50,510	49,044
Inventory	140,467	125,445
Other current assets	136,238	77,782
Total current assets	1,671,423	1,426,183
Property and equipment, net of accumulated depreciation of $32,612 and $28,149 as of March 31, 2019, and December 31, 2018, respectively	106,280	97,024
Intangible assets, net of accumulated amortization of $4,276 and $3,852 as of March 31, 2019, and December 31, 2018, respectively	11,781	11,574
Right of use asset, net of accumulated amortization of $1,491 and nil as of March 31, 2019 and December 31, 2018, respectively	41,098
Other assets	133,313	107,294
Total assets	1,963,895	1,642,075
Current liabilities:
Accounts payable	26,499	33,829
Accrued expenses	100,120	134,095
Deferred revenue	3,985	3,303
Other current liabilities	6,762	2,463
Total current liabilities	137,366	173,690
Long-term debt	425,752	420,554
Lease liabilities	52,165
Deferred rent and other	48	15,555
Total liabilities	615,331	609,799
Commitments and contingencies (Note 15)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 3,333,333 shares authorized; none issued and outstanding
Common stock, $0.0001 par value, 99,000,000 shares authorized; 74,133,521 and 71,071,887 issued and outstanding at March 31, 2019, and December 31, 2018, respectively	7	7
Additional paid-in capital	3,004,107	2,611,294
Accumulated other comprehensive income (loss)	19	(99)
Accumulated deficit	(1,655,569)	(1,578,926)
Total stockholders’ equity	1,348,564	1,032,276
Total liabilities and stockholders’ equity	$ 1,963,895	$ 1,642,075