UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 92,180	$ 93,026
Marketable securities	101,733	126,052
Total cash, cash equivalents, and marketable securities	193,913	219,078
Trade accounts receivable, net of allowance of $5,028 and $4,631	202,399	211,846
Deferred income taxes	12,414	12,380
Income taxes receivable	4,898	4,770
Other current assets	23,199	10,791
Total current assets	436,823	458,865
Property and equipment, net	35,940	31,319
Long-term deferred income taxes	52,536	53,350
Long-term other assets	3,728	4,030
Intangible assets, net	30,431	33,418
Goodwill	46,724	46,776
Total assets	606,182	627,758
Current liabilities:
Accounts payable	11,978	12,675
Accrued expenses	46,062	42,768
Accrued compensation and related expenses	32,472	55,872
Deferred revenue	158,181	155,873
Total current liabilities	248,693	267,188
Income taxes payable	5,648	5,618
Long-term deferred revenue	13,458	15,805
Other long-term liabilities	15,879	16,288
Total liabilities	$ 283,678	$ 304,899
Stockholders' equity:
Preferred stock, 1,000 shares authorized; no shares issued and outstanding
Common stock, 200,000 shares authorized; 76,385 shares and 76,488 shares issued and outstanding	$ 764	$ 765
Additional paid-in capital	138,075	145,418
Retained earnings	186,893	180,183
Accumulated other comprehensive loss	(3,228)	(3,507)
Total stockholders' equity	322,504	322,859
Total liabilities and stockholders' equity	$ 606,182	$ 627,758