Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 977,488	$ 313,382
Marketable securities	879,483	398,554
Accounts receivable, net of reserves of $1,065 and $1,281 at June 30, 2018, and December 31, 2017, respectively	479,865	461,457
Prepaid expenses and other current assets	147,324	172,853
Total current assets	2,484,160	1,346,246
Property and equipment, net	852,950	862,535
Marketable securities	411,746	567,592
Goodwill	1,494,311	1,498,688
Acquired intangible assets, net	184,934	201,259
Deferred income tax assets	44,230	36,231
Other assets	132,373	136,365
Total assets	5,604,704	4,648,916
Current liabilities:
Accounts payable	84,167	80,278
Accrued expenses	253,241	283,743
Deferred revenue	100,314	70,495
Convertible senior notes	674,629	0
Other current liabilities	23,977	22,178
Total current liabilities	1,136,328	456,694
Deferred revenue	6,075	6,062
Deferred income tax liabilities	18,236	17,823
Convertible senior notes	855,378	662,913
Other liabilities	143,409	142,955
Total liabilities	2,159,426	1,286,447
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock, $0.01 par value; 5,000,000 shares authorized; 700,000 shares designated as Series A Junior Participating Preferred Stock; no shares issued or outstanding	0	0
Common stock, $0.01 par value; 700,000,000 shares authorized; 171,763,861 shares issued and 169,311,093 shares outstanding at June 30, 2018, and 169,893,324 shares issued and outstanding at December 31, 2017	1,718	1,699
Additional paid-in capital	4,303,531	4,073,362
Accumulated other comprehensive loss	(41,970)	(21,930)
Treasury stock, at cost, 2,452,768 shares at June 30, 2018, and no shares at December 31, 2017	(185,512)	0
Accumulated deficit	(632,489)	(690,662)
Total stockholders’ equity	3,445,278	3,362,469
Total liabilities and stockholders’ equity	$ 5,604,704	$ 4,648,916