CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 90,427	$ 420,244
Restricted cash	964	938
Short-term investments	609,167	254,927
Accounts receivable, net	125,115	165,364
Prepaid expenses and other current assets	27,863	19,180
Total current assets	853,536	860,653
Property and equipment, net	51,918	53,359
Capitalized software development costs, net	0	2,499
Deposits and other assets	7,112	7,411
Deferred tax assets, net	14,761	9,297
Total assets	927,327	933,219
Current liabilities:
Accounts payable and accrued expenses	22,670	30,711
Accrued compensation and employee benefits	38,617	41,498
Deferred revenue and advance payments	175,358	198,734
Total current liabilities	236,645	270,943
Deferred revenue and advance payments	5,816	6,400
Other long-term liabilities	64,503	50,146
Deferred tax liabilities	4	4
Total liabilities	306,968	327,493
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	570,502	559,918
Treasury stock, at cost; 6,405 shares	(475,184)	(475,184)
Accumulated other comprehensive loss	(8,111)	(5,659)
Retained earnings	533,134	526,633
Total stockholders' equity	620,359	605,726
Total liabilities and stockholders' equity	927,327	933,219
Class A
Stockholders' Equity
Common stock	16	16
Class B Convertible
Stockholders' Equity
Common stock	$ 2	$ 2