Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 363,703	$ 313,382
Marketable securities	447,850	398,554
Accounts receivable, net of reserves of $1,311 and $1,281 at March 31, 2018, and December 31, 2017, respectively	484,617	461,457
Prepaid expenses and other current assets	163,556	172,853
Total current assets	1,459,726	1,346,246
Property and equipment, net	845,118	862,535
Marketable securities	512,270	567,592
Goodwill	1,498,906	1,498,688
Acquired intangible assets, net	193,228	201,259
Deferred income tax assets	44,490	36,231
Other assets	133,166	136,365
Total assets	4,686,904	4,648,916
Current liabilities:
Accounts payable	81,239	80,278
Accrued expenses	253,075	283,743
Deferred revenue	95,490	70,495
Current portion of convertible senior notes	668,745	0
Other current liabilities	32,046	22,178
Total current liabilities	1,130,595	456,694
Deferred revenue	7,049	6,062
Deferred income tax liabilities	17,675	17,823
Convertible senior notes	0	662,913
Other liabilities	145,328	142,955
Total liabilities	1,300,647	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; 170,841,758 and 169,893,324 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively	1,708	1,699
Additional paid-in capital	4,098,218	4,073,362
Accumulated other comprehensive loss	(18,334)	(21,930)
Treasury stock, at cost, 293,619 shares at March 31, 2018, and no shares at December 31, 2017	(19,785)	0
Accumulated deficit	(675,550)	(690,662)
Total stockholders’ equity	3,386,257	3,362,469
Total liabilities and stockholders’ equity	$ 4,686,904	$ 4,648,916