Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 347,845	$ 206,279
Marketable securities	125,710
Deferred tax assets	1,913	693
Prepaid expenses and other current assets	4,521	5,015
Total current assets	479,989	211,987
Marketable securities	18,448
Property and equipment, net	15,740	10,920
Intangible assets, net	28,219
Goodwill	13,128
Restricted cash and other non-current assets	1,215	1,483
Total assets	556,739	224,390
Current liabilities:
Accounts payable	2,954	4,359
Accrued expenses and other current liabilities	14,649	5,175
Deferred revenue, current portion	25,375	25,340
Total current liabilities	42,978	34,874
Deferred rent, net of current portion	8,674	6,740
Deferred revenue, net of current portion	5,302	30,208
Contingent consideration, net of current portion	6,321
Deferred tax liabilities	1,913	693
Other non-current liabilities	294	208
Total liabilities	65,482	72,723
Commitments and contingencies (Note 9)
Stockholders' equity:
Preferred stock, $0.01 par value, 5,000 shares authorized; 0 shares issued and outstanding at December 31, 2014 and December 31, 2013
Common stock, $0.01 par value, 125,000 shares authorized; 32,340 and 23,940 shares issued and outstanding at December 31, 2014 and December 31, 2013, respectively	323	239
Additional paid-in capital	638,389	250,103
Accumulated other comprehensive loss	(71)
Accumulated deficit	(147,384)	(98,675)
Total stockholders' equity	491,257	151,667
Total liabilities and stockholders' equity	$ 556,739	$ 224,390