Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
ASSETS
Cash and cash equivalents	$ 331,367	$ 350,945
Restricted Cash and Cash Equivalents, Current	402	0
Accounts receivable, net of allowances of $9,850 and $8,701, respectively	174,411	234,195
Prepaid expenses and other current assets	31,588	35,287
Total current assets	537,768	620,427
Long-term investments	64,947	57,722
Property and equipment, net	85,852	79,773
Trade names, net	127,450	123,947
Patent and patent licenses, net	9,879	10,871
Customer relationships, net	202,973	193,606
Goodwill	1,257,521	1,196,611
Other purchased intangibles, net	154,287	157,327
Other assets	11,541	12,809
Total assets	2,452,218	2,453,093
LIABILITIES AND STOCKHOLDERS’ EQUITY
Accounts payable and accrued expenses	127,713	169,837
Deferred revenue, current	(113,940)	(95,255)
Other current liabilities	291	10
Total current liabilities	241,944	265,102
Long-term debt	1,004,796	1,001,944
Deferred revenue, non-current	8,018	47
Accrued Income Taxes, Noncurrent	43,781	43,781
Liability for uncertain tax positions	53,311	52,216
Deferred income taxes, non-current	33,691	38,264
Other long-term liabilities	35,509	31,434
Total liabilities	1,421,050	1,432,788
Commitments and contingencies	0	0
Additional paid-in capital	332,407	325,854
Retained earnings	723,562	723,062
Accumulated other comprehensive loss	(25,280)	(29,090)
Stockholders' Equity Attributable to Parent	1,031,168	1,020,305
Total liabilities and stockholders’ equity	2,452,218	2,453,093
Common stock, $0.01 par value. Authorized 95,000,000; total issued and outstanding 47,893,150 and 47,854,510 shares, respectively	479	479
Series A Preferred Stock [Member]
LIABILITIES AND STOCKHOLDERS’ EQUITY
Preferred stock, $0.01 par value	0	0
Series B Preferred Stock [Member]
LIABILITIES AND STOCKHOLDERS’ EQUITY
Preferred stock, $0.01 par value	$ 0	$ 0