Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 254,165	$ 333,891
Marketable securities	502,608	340,005
Accounts receivable, net of reserves of $6,618 and $3,703 at June 30, 2014 and December 31, 2013, respectively	325,385	271,988
Prepaid expenses and other current assets	88,047	62,096
Deferred income tax assets	29,462	21,734
Total current assets	1,199,667	1,029,714
Property and equipment, net	536,637	450,287
Marketable securities	735,629	573,026
Goodwill	1,049,047	757,368
Acquired intangible assets, net	149,218	77,429
Deferred income tax assets	2,317	2,325
Other assets	96,142	67,536
Total assets	3,768,657	2,957,685
Current liabilities:
Accounts payable	70,534	73,710
Accrued expenses	158,646	150,385
Deferred revenue	48,182	36,952
Other current liabilities	5,930	2,119
Total current liabilities	283,292	263,166
Deferred revenue	4,056	3,199
Deferred income tax liabilities	40,385	4,737
Convertible senior notes	595,385	0
Other liabilities	72,795	57,152
Total liabilities	995,913	328,254
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; 181,546,263 shares issued and 178,270,354 shares outstanding at June 30, 2014 and 178,580,696 shares issued and outstanding at December 31, 2013	1,844	1,808
Additional paid-in capital	4,742,423	4,561,929
Accumulated other comprehensive income (loss)	2,497	(2,091)
Treasury stock, at cost, 3,275,909 shares at June 30, 2014 and no shares at December 31, 2013	(187,491)	0
Accumulated deficit	(1,786,529)	(1,932,215)
Total stockholders’ equity	2,772,744	2,629,431
Total liabilities and stockholders’ equity	$ 3,768,657	$ 2,957,685