Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 1,612,679	$ 618,766
Short-term investments, available-for-sale	173,601	583,615
Accounts receivable, net of allowances of $6,323 and $4,530 at March 31, 2019 and December 31, 2018, respectively	482,647	688,420
Inventories, net	23,145	21,905
Prepaid expenses and other current assets	160,938	174,195
Total current assets	2,453,010	2,086,901
Long-term investments, available-for-sale	86,340	574,319
Property and equipment, net	243,132	243,396
Operating lease right-of-use assets	191,951	0
Goodwill	1,802,756	1,802,670
Other intangible assets, net	155,091	167,187
Deferred tax assets, net	104,448	136,998
Other assets	130,728	124,578
Total assets	5,167,456	5,136,049
Current liabilities:
Accounts payable	81,476	75,551
Accrued expenses and other current liabilities	292,663	290,492
Income taxes payable	2,220	44,409
Current portion of convertible notes	1,163,199	1,155,445
Current portion of deferred revenues	1,303,210	1,345,243
Total current liabilities	2,842,768	2,911,140
Long-term portion of deferred revenues	453,507	489,329
Long-term debt	742,100	741,825
Long-term income taxes payable	285,626	285,627
Operating lease liabilities	203,580	0
Other liabilities	83,834	148,499
Commitments and contingencies
Temporary equity from convertible notes	1,163	8,110
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; 311,732 and 309,761 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	312	310
Additional paid-in capital	5,495,935	5,404,500
Retained earnings	4,232,181	4,169,019
Accumulated other comprehensive loss	(5,483)	(8,154)
Stockholders' equity before treasury stock	9,722,945	9,565,675
Less - common stock in treasury, at cost (179,832 and 178,327 shares at March 31, 2019 and December 31, 2018, respectively)	(9,168,067)	(9,014,156)
Total stockholders' equity	554,878	551,519
Total liabilities, temporary equity and stockholders' equity	$ 5,167,456	$ 5,136,049