CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 11,187	$ 134,279
Accounts receivable (less allowance for doubtful accounts of $3,846 in 2019 and $4,647 in 2018)	381,379	298,912
Short-term investments	31,184	44,306
Prepaid expenses	26,881	33,258
Income tax receivable	0	4,697
Other current assets	2,939	3,406
Total current assets	453,570	518,858
Accounts receivable, long-term	20,511	16,020
Operating lease right-of-use assets	20,349	0
Property and equipment, net	170,150	155,177
Other assets:
Goodwill	835,911	753,718
Other intangibles, net	377,478	276,852
Non-current investments and other assets	71,462	70,338
Total assets	1,949,431	1,790,963
Current liabilities:
Accounts payable	8,062	6,910
Accrued liabilities	70,894	66,480
Operating lease liabilities	6,039	0
Current income tax payable	249	0
Deferred revenue	368,488	350,512
Total current liabilities	453,732	423,902
Revolving line of credit	15,000	0
Deferred revenue, long-term	551	424
Deferred income taxes	39,749	41,791
Operating lease liabilities, long-term	18,769	0
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 June 30, 2019 and December 31, 2018	481	481
Additional paid-in capital	715,920	731,435
Accumulated other comprehensive loss, net of tax	(46)	(46)
Retained earnings	830,156	771,925
Treasury stock, at cost; 9,581,990 and 9,872,505 shares in 2019 and 2018, respectively	(124,881)	(178,949)
Total shareholders' equity	1,421,630	1,324,846
Total liabilities and shareholders' equity	$ 1,949,431	$ 1,790,963