Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 312,912	$ 289,473
Marketable securities	524,958	460,088
Accounts receivable, net of reserves of $9,380 and $7,364 at March 31, 2016, and December 31, 2015, respectively	365,103	380,399
Prepaid expenses and other current assets	127,855	123,228
Total current assets	1,330,828	1,253,188
Property and equipment, net	770,197	753,180
Marketable securities	685,362	774,674
Goodwill	1,152,376	1,150,244
Acquired intangible assets, net	149,379	156,095
Deferred income tax assets	3,490	4,700
Other assets	92,120	89,603
Total assets	4,183,752	4,181,684
Current liabilities:
Accounts payable	63,822	61,982
Accrued expenses	197,487	216,166
Deferred revenue	64,905	54,154
Other current liabilities	7,019	138
Total current liabilities	333,233	332,440
Deferred revenue	4,238	4,163
Deferred income tax liabilities	11,706	12,888
Convertible senior notes	623,485	618,047
Other liabilities	97,508	93,268
Total liabilities	$ 1,070,170	$ 1,060,806
Commitments and contingencies
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; 178,270,472 shares issued and 176,050,217 shares outstanding at March 31, 2016, and 177,212,181 shares issued and outstanding at December 31, 2015	1,783	1,772
Additional paid-in capital	4,451,319	4,437,420
Accumulated other comprehensive loss	(28,792)	(41,453)
Treasury stock, at cost, 2,220,255 shares at March 31, 2016, and no shares at December 31, 2015	(108,725)	0
Accumulated deficit	(1,202,003)	(1,276,861)
Total stockholders’ equity	3,113,582	3,120,878
Total liabilities and stockholders’ equity	$ 4,183,752	$ 4,181,684