CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 467,779	$ 547,178
Marketable debt securities	836,346	975,017
Marketable equity securities	38,078	13,967
Accounts receivable, net	75,572	43,011
Inventory	68,300	56,348
Prepaid expenses and other current assets	98,698	80,343
Total current assets	1,584,773	1,715,864
Property, plant and equipment, net	429,814	425,179
Operating lease right-of-use assets	221,280	221,197
Restricted investments	24,725	14,825
Other assets	19,032	18,069
Total assets	2,279,624	2,395,134
Current liabilities:
Accounts payable	40,484	49,884
Accrued expenses	183,221	197,201
Operating lease liability	29,043	27,688
Deferred revenue	86,043	77,821
Total current liabilities	338,791	352,594
Operating lease liability, net of current portion	275,782	276,135
Deferred revenue, net of current portion	306,124	318,383
Other liabilities	9,198	9,330
Total liabilities	929,895	956,442
Commitments and contingencies (Note 14)
Stockholders’ equity:
Preferred stock, $0.01 par value per share, 5,000 shares authorized and no shares issued and outstanding as of March 31, 2020 and December 31, 2019	0	0
Common stock, $0.01 par value per share, 250,000 shares authorized; 113,168 shares issued and outstanding as of March 31, 2020; 112,188 shares issued and outstanding as of December 31, 2019	1,131	1,122
Additional paid-in capital	5,289,966	5,201,176
Accumulated other comprehensive loss	(32,059)	(36,518)
Accumulated deficit	(3,909,309)	(3,727,088)
Total stockholders’ equity	1,349,729	1,438,692
Total liabilities and stockholders’ equity	$ 2,279,624	$ 2,395,134
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, shares outstanding (in shares)	113,168,000	112,188,000