CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 161,438	$ 134,279
Accounts receivable (less allowance for doubtful accounts of $4,302 in 2019 and $4,647 in 2018)	347,982	298,912
Short-term investments	32,931	44,306
Prepaid expenses	24,544	33,258
Income tax receivable	4	4,697
Other current assets	2,907	3,406
Total current assets	569,806	518,858
Accounts receivable, long-term	20,437	16,020
Operating lease right-of-use assets	20,172
Property and equipment, net	169,950	155,177
Other assets:
Goodwill	826,040	753,718
Other intangibles, net	377,580	276,852
Non-current investments and other assets	71,104	70,338
Total assets	2,055,089	1,790,963
Current liabilities:
Accounts payable	9,060	6,910
Accrued liabilities	69,781	66,480
Operating lease liabilities	6,413
Current income tax payable	0	0
Deferred revenue	391,560	350,512
Total current liabilities	476,814	423,902
Revolving line of credit	0	0
Deferred revenue, long-term	241	424
Deferred income taxes	40,303	41,791
Operating lease liabilities, long-term	18,134
Commitments and contingencies	0	0
Shareholders' equity:
Preferred stock, $10.00 par value; 1,000,000 shares authorized; none issued	0	0
Common stock, $0.01 par value; 100,000,000 shares authorized; 48,147,969 shares issued and outstanding as of September 30, 2019 and December 31, 2018	481	481
Additional paid-in capital	692,586	731,435
Accumulated other comprehensive loss, net of tax	(46)	(46)
Retained earnings	870,546	771,925
Treasury stock, at cost; 9,172,316 and 9,872,505 shares in 2019 and 2018, respectively	(43,970)	(178,949)
Total shareholders' equity	1,519,597	1,324,846
Total liabilities and shareholders' equity	$ 2,055,089	$ 1,790,963