Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 309,171	$ 603,623
Accounts receivable (less allowance for losses and sales adjustments of $12,086 in 2021 and $9,255 in 2020)	521,059	382,319
Short-term investments	52,300	72,187
Prepaid expenses	55,513	30,864
Income tax receivable	18,137	21,598
Other current assets	8,151	2,479
Total current assets	964,331	1,113,070
Accounts receivable, long-term	13,937	21,417
Operating lease right-of-use assets	39,720	18,734
Property and equipment, net	181,193	168,004
Other assets:
Software development costs, net	28,489	9,121
Goodwill	2,359,674	838,428
Other intangibles, net	1,052,493	322,068
Non-current investments	46,353	82,640
Other non-current assets	45,971	33,792
Total assets	4,732,161	2,607,274
Current liabilities:
Accounts payable	119,988	14,011
Accrued liabilities	158,424	83,084
Operating lease liabilities	10,560	5,904
Deferred revenue	510,529	461,278
Current portion of term loans	30,000	0
Total current liabilities	829,501	564,277
Revolving line of credit	0	0
Term loans, net	718,511	0
Convertible senior notes due 2026, net	592,765	0
Deferred revenue, long-term	38	100
Deferred income taxes	228,085	40,507
Operating lease liabilities, long-term	36,336	16,279
Other long-term liabilities	2,893	0
Commitments and contingencies	0	0
Total liabilities	2,408,129	621,163
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 in 2021 and 2020	481	481
Additional paid-in capital	1,075,650	905,332
Accumulated other comprehensive loss, net of tax	(46)	(46)
Retained earnings	1,273,614	1,112,156
Treasury stock, at cost; 6,832,640 and 7,608,627 shares in 2021 and 2020, respectively	(25,667)	(31,812)
Total shareholders' equity	2,324,032	1,986,111
Total liabilities and shareholders' equity	$ 4,732,161	$ 2,607,274