Condensed Consolidated Income Statements (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Revenue:
Product and maintenance	$ 487,870	$ 443,847	$ 968,479	$ 895,254
Services	30,521	35,154	67,225	60,658
Total revenue	518,391	479,001	1,035,704	955,912
Costs and Expenses:
Cost of product and maintenance	40,127	38,829	81,857	82,546
Cost of services	18,833	22,003	40,312	40,078
Marketing and sales	109,300	103,897	218,448	207,244
Research and development	219,129	195,901	443,314	394,187
General and administrative	34,875	32,774	68,174	64,590
Amortization of acquired intangibles	3,518	3,836	7,148	7,692
Restructuring and other credits	(447)	(929)	(2,438)	(2,717)
Total costs and expenses	425,335	396,311	856,815	793,620
Income from operations	93,056	82,690	178,889	162,292
Interest expense	(6,669)	(6,248)	(13,644)	(12,727)
Other income, net	3,638	924	2,949	1,983
Income before provision for income taxes	90,025	77,366	168,194	151,548
Provision for income taxes	14,876	8,239	20,160	14,162
Net income	$ 75,149	$ 69,127	$ 148,034	$ 137,386
Net income per share - basic (in usd per share)	$ 0.27	$ 0.25	$ 0.54	$ 0.51
Net income per share - diluted (in usd per share)	$ 0.27	$ 0.25	$ 0.53	$ 0.49
Weighted average common shares outstanding - basic (in shares)	273,564	271,887	273,703	271,030
Weighted average common shares outstanding - diluted (in shares)	280,774	279,526	281,247	278,631