UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 66,383	$ 93,026
Marketable securities	63,347	126,052
Total cash, cash equivalents, and marketable securities	129,730	219,078
Trade accounts receivable, net of allowance of $4,564 and $4,631	208,562	211,846
Deferred income taxes	12,409	12,380
Income taxes receivable	13,639	4,770
Other current assets	14,319	10,791
Total current assets	378,659	458,865
Property and equipment, net	39,343	31,319
Long-term deferred income taxes	53,905	53,350
Long-term other assets	3,755	4,030
Intangible assets, net	47,462	33,418
Goodwill	73,871	46,776
Total assets	596,995	627,758
Current liabilities:
Accounts payable	8,824	12,675
Accrued expenses	36,370	42,768
Accrued compensation and related expenses	52,070	55,872
Deferred revenue	140,458	155,873
Total current liabilities	237,722	267,188
Income taxes payable	5,253	5,618
Long-term deferred revenue	10,228	15,805
Other long-term liabilities	16,372	16,288
Total liabilities	269,575	304,899
Stockholders' equity:
Preferred stock, 1,000 shares authorized; no shares issued and outstanding
Common stock, 200,000 shares authorized; 76,284 shares and 76,488 shares issued and outstanding	763	765
Additional paid-in capital	143,020	145,418
Retained earnings	188,376	180,183
Accumulated other comprehensive loss	(4,739)	(3,507)
Total stockholders' equity	327,420	322,859
Total liabilities and stockholders' equity	$ 596,995	$ 627,758

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.