Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 143,944	$ 98,810
Marketable investments (Note 2)	120,608	134,876
Accounts receivable, net	49,160	74,623
Deferred commissions	9,616	9,410
Prepaid expenses and other current assets	18,036	18,846
Total current assets	341,364	336,565
Long-term marketable investments (Note 2)	8,926	8,970
Property and equipment, net	44,554	46,300
Goodwill	78,152	78,954
Intangible assets, net	7,291	7,920
Other assets	9,815	9,123
Total assets	490,102	487,832
Current Liabilities:
Accounts payable	922	772
Accrued expenses and other current liabilities	29,586	30,078
Deferred revenue	152,188	150,479
Total current liabilities	182,696	181,329
Non-current liabilities	9,318	9,433
Total liabilities	192,014	190,762
Commitments
Stockholders' Equity (Note 6):
Preferred stock, $.01 par value, Authorized - 500 shares, issued and outstanding - none
Common stock, $.01 par value, Authorized - 125,000 shares, Issued - 31,522 and 31,451 as of March 31, 2013 and December 31, 2012, respectively; Outstanding - 22,364 and 22,293 as of March 31, 2013 and December 31, 2012, respectively	315	315
Additional paid-in capital	392,790	389,362
Retained earnings	116,639	117,648
Treasury stock - 9,158 as of March 31, 2013 and December 31, 2012, at cost	(210,843)	(210,843)
Accumulated other comprehensive income (loss)	(813)	588
Total stockholders' equity	298,088	297,070
Total liabilities and stockholders' equity	$ 490,102	$ 487,832