Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 333,891	$ 201,989
Marketable securities	340,005	235,592
Accounts receivable, net of reserves of $3,703 and $3,807 at December 31, 2013 and 2012, respectively	271,988	218,777
Prepaid expenses and other current assets	62,096	51,604
Deferred income tax assets	21,734	20,422
Total current assets	1,029,714	728,384
Property and equipment, net	450,287	345,091
Marketable securities	573,026	657,659
Goodwill	757,368	723,701
Acquired intangible assets, net	77,429	84,554
Deferred income tax assets	2,325	21,427
Other assets	67,536	39,811
Total assets	2,957,685	2,600,627
Current liabilities:
Accounts payable	73,710	43,291
Accrued expenses	150,385	133,087
Deferred revenue	36,952	26,291
Other current liabilities	2,119	275
Total current liabilities	263,166	202,944
Deferred revenue	3,199	2,565
Deferred income tax liabilities	4,737	0
Other liabilities	57,152	49,364
Total liabilities	328,254	254,873
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; 178,580,696 shares issued and outstanding at December 31, 2013; 200,199,536 shares issued and 177,782,814 shares outstanding at December 31, 2012	1,808	2,015
Additional paid-in capital	4,561,929	5,195,543
Treasury stock, at cost, no shares at December 31, 2013 and 22,416,722 shares at December 31, 2012	0	(624,462)
Accumulated other comprehensive loss	(2,091)	(1,640)
Accumulated deficit	(1,932,215)	(2,225,702)
Total stockholders’ equity	2,629,431	2,345,754
Total liabilities and stockholders’ equity	$ 2,957,685	$ 2,600,627