Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 501,112	$ 752,895
Short-term investments, available-for-sale	19,900	124,113
Accounts receivable, net of allowances of $23,471 and $25,868 at June 30, 2021 and December 31, 2020, respectively	665,519	858,009
Inventories, net	21,699	20,089
Prepaid expenses and other current assets	291,388	236,000
Total current assets	1,499,618	1,991,106
Long-term investments, available-for-sale	10,978	14,365
Property and equipment, net	225,801	208,811
Operating lease right-of-use assets, net	191,855	187,129
Goodwill	3,456,014	1,798,408
Other intangible assets, net	852,657	81,491
Deferred tax assets, net	234,375	386,504
Other assets	243,155	222,533
Total assets	6,714,453	4,890,347
Current liabilities:
Accounts payable	138,267	92,266
Accrued expenses and other current liabilities	373,846	507,185
Income taxes payable	38,655	42,760
Current portion of deferred revenues	1,541,606	1,510,216
Total current liabilities	2,092,374	2,152,427
Long-term portion of deferred revenues	350,345	392,360
Long-term debt	3,473,929	1,732,622
Long-term income taxes payable	204,782	232,086
Operating lease liabilities	193,141	195,767
Other liabilities	107,035	72,942
Commitments and contingencies
Stockholders' equity:
Preferred stock at $.01 par value: 5,000 shares authorized, none issued and outstanding	0	0
Common stock at $.001 par value: 1,000,000 shares authorized; 324,387 and 321,964 shares issued and outstanding at June 30, 2021 and December 31, 2020, respectively	324	322
Additional paid-in capital	6,835,867	6,608,018
Retained earnings	5,041,270	4,984,333
Accumulated other comprehensive loss	(6,015)	(3,649)
Stockholders' equity before treasury stock	11,871,446	11,589,024
Less - common stock in treasury, at cost (200,172 and 199,443 shares at June 30, 2021 and December 31, 2020, respectively)	(11,578,599)	(11,476,881)
Total stockholders' equity	292,847	112,143
Total liabilities and stockholders' equity	$ 6,714,453	$ 4,890,347