CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 420,244	$ 401,975
Restricted cash	938	737
Short-term investments	254,927	187,408
Accounts receivable, net	69,500	83,319
Prepaid expenses and other current assets	18,002	11,548
Total current assets	763,611	684,987
Property and equipment, net	53,359	57,436
Capitalized software development costs, net	2,499	8,497
Deposits and other assets	2,868	5,695
Deferred tax assets, net	13,391	11,704
Total assets	835,728	768,319
Current liabilities:
Accounts payable and accrued expenses	30,711	36,628
Accrued compensation and employee benefits	41,498	43,323
Deferred revenue and advance payments, net	112,649	105,535
Total current liabilities	184,858	185,486
Deferred revenue and advance payments, net	10,181	13,915
Other long-term liabilities	50,146	16,447
Deferred tax liabilities	4	294
Total liabilities	245,189	216,142
Commitments and Contingencies
Stockholders’ Equity
Preferred stock undesignated, $0.001 par value; 5,000 shares authorized; no shares issued or outstanding	0	0
Additional paid-in capital	559,918	543,974
Treasury stock, at cost; 6,405 shares	(475,184)	(475,184)
Accumulated other comprehensive loss	(5,968)	(10,743)
Retained earnings	511,755	494,112
Total stockholders’ equity	590,539	552,177
Total liabilities and stockholders’ equity	835,728	768,319
Class A
Stockholders’ Equity
Common stock	16	16
Total stockholders’ equity	16	16
Class B Convertible
Stockholders’ Equity
Common stock	2	2
Total stockholders’ equity	$ 2	$ 2

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

Name:	us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent
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.