Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 43,366	$ 39,517
Marketable securities	222,625	233,284
Accounts receivable, net of allowance for doubtful accounts of $1,945 and $1,517, respectively	93,507	68,475
Prepaid commission expense	2,232	2,819
Prepaid expenses and other current assets	15,701	13,661
Deferred income taxes	4,158	96
Total current assets	381,589	357,852
Restricted cash	5,582	5,118
Furniture, fixtures and equipment, net	42,491	38,579
Marketable securities- long-term	206,426	183,842
Goodwill	19,083	19,025
Intangible assets, net	1,394	1,816
Deferred income taxes- long-term	8,004	8,066
Other assets	7,756	7,919
Total assets	672,325	622,217
Current liabilities:
Accounts payable	2,766	3,738
Accrued payroll and other compensation	15,430	15,574
Accrued expenses and other	16,086	12,638
Deferred revenue	80,583	62,890
Total current liabilities	114,865	94,840
Noncurrent liabilities:
1.00% convertible senior notes, net	246,748	240,886
Deferred revenue, less current portion	933	1,374
Deferred tax liabilities	232	238
Other long-term liabilities	21,069	20,180
Total noncurrent liabilities	268,982	262,678
Total liabilities	$ 383,847	$ 357,518
Commitments and contingencies
Stockholders' equity:
Preferred stock, par value $0.01 per share; 5,000 shares authorized, none issued and outstanding	$ 0	$ 0
Common stock, par value $0.01 per share; 200,000 shares authorized, 57,567 and 56,301 shares issued; 55.285 and 54,413 shares outstanding, respectively	576	563
Additional paid-in capital	339,408	301,465
Treasury stock, 2,282 and 1,888 shares, respectively	(61,204)	(45,049)
Accumulated other comprehensive loss	(1,604)	(1,912)
Retained earnings	11,302	9,632
Total stockholders' equity	288,478	264,699
Total liabilities and stockholders' equity	$ 672,325	$ 622,217