Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 235,015	$ 201,989
Marketable securities	331,300	235,592
Accounts receivable, net of reserves of $3,584 and $3,807 at September 30, 2013 and December 31, 2012, respectively	256,453	218,777
Prepaid expenses and other current assets	67,452	51,604
Deferred income tax assets	20,422	20,422
Total current assets	910,642	728,384
Property and equipment, net	424,605	345,091
Marketable securities	620,204	657,659
Goodwill	751,271	723,701	[1]
Acquired intangible assets, net	79,803	84,554
Deferred income tax assets	20,672	21,427
Other assets	77,928	39,811
Total assets	2,885,125	2,600,627
Current liabilities:
Accounts payable	49,073	43,291
Accrued expenses	171,527	133,087
Deferred revenue	37,025	26,291
Other current liabilities	27,799	275
Total current liabilities	285,424	202,944
Deferred revenue	2,643	2,565
Other liabilities	53,928	49,364
Total liabilities	341,995	254,873
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; 203,958,959 shares issued and 178,707,441 shares outstanding at September 30, 2013 and 200,199,536 shares issued and 177,782,814 shares outstanding at December 31, 2012	2,059	2,015
Additional paid-in capital	5,295,939	5,195,543
Accumulated other comprehensive loss	(5,434)	(1,640)
Treasury stock, at cost, 25,251,518 shares at September 30, 2013 and 22,416,722 shares at December 31, 2012	(736,870)	(624,462)
Accumulated deficit	(2,012,564)	(2,225,702)
Total stockholders’ equity	2,543,130	2,345,754
Total liabilities and stockholders’ equity	$ 2,885,125	$ 2,600,627

[1] Balance as of January 1, 2013 has been revised to reflect purchase accounting measurement period adjustments (Note 6).