Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 513,306	$ 368,518
Short-term investments, available-for-sale	642,448	502,852
Accounts receivable, net of allowances of $6,113 and $7,719 at March 31, 2016 and December 31, 2015, respectively	450,000	669,276
Inventories, net	12,194	10,521
Prepaid expenses and other current assets	169,622	132,784
Total current assets	1,787,570	1,683,951
Long-term investments, available-for-sale	849,490	891,964
Property and equipment, net	376,012	373,817
Goodwill	1,962,232	1,962,722
Other intangible assets, net	281,796	283,418
Deferred tax assets, net	205,938	215,196
Other assets	55,651	56,449
Total assets	5,518,689	5,467,517
Current liabilities:
Accounts payable	85,490	95,396
Accrued expenses and other current liabilities	310,881	317,468
Income taxes payable	18,458	18,351
Current portion of deferred revenues	1,209,435	1,249,754
Total current liabilities	1,624,264	1,680,969
Long-term portion of deferred revenues	412,580	414,314
Convertible notes	1,320,240	1,311,071
Other liabilities	$ 93,525	$ 87,717
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; 300,698 and 299,113 shares issued and outstanding at March 31, 2016 and December 31, 2015, respectively	301	299
Additional paid-in capital	4,632,163	4,566,919
Retained earnings	3,558,088	3,474,625
Accumulated other comprehensive loss	(21,063)	(28,527)
Stockholders' equity before treasury stock	8,169,489	8,013,316
Less - common stock in treasury, at cost (146,151 and 145,296 shares at March 31, 2016 and December 31, 2015, respectively)	(6,101,409)	(6,039,870)
Total stockholders' equity	2,068,080	1,973,446
Total liabilities and stockholders' equity	$ 5,518,689	$ 5,467,517