Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 313,382	$ 324,169
Marketable securities	398,554	512,849
Accounts receivable, net of reserves of $1,279 and $6,145 at December 31, 2017 and 2016, respectively	459,127	368,596
Prepaid expenses and other current assets	137,809	104,303
Total current assets	1,308,872	1,309,917
Property and equipment, net	862,535	801,017
Marketable securities	567,592	779,311
Goodwill	1,498,688	1,228,503
Acquired intangible assets, net	201,259	149,463
Deferred income tax assets	51,069	8,982
Other assets	112,829	95,953
Total assets	4,602,844	4,373,146
Current liabilities:
Accounts payable	80,278	76,120
Accrued expenses	283,743	238,777
Deferred revenue	77,705	52,972
Other current liabilities	22,178	6,719
Total current liabilities	463,904	374,588
Deferred revenue	6,839	3,758
Deferred income tax liabilities	15,510	11,652
Convertible senior notes	662,913	640,087
Other liabilities	142,955	118,691
Total liabilities	1,292,121	1,148,776
Commitments and contingencies (Note 12)
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; 169,893,324 and 173,254,797 shares issued and outstanding at December 31, 2017 and 2016, respectively	1,699	1,733
Additional paid-in capital	4,073,362	4,239,588
Accumulated other comprehensive loss	(21,930)	(56,222)
Accumulated deficit	(742,408)	(960,729)
Total stockholders’ equity	3,310,723	3,224,370
Total liabilities and stockholders’ equity	$ 4,602,844	$ 4,373,146