Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net sales:
Product	$ 1,116,703	$ 1,113,590	$ 1,143,000
Software maintenance	111,476	111,866	100,862
Total net sales	1,228,179	1,225,456	1,243,862
Cost of sales:
Product	306,730	311,226	312,623
Software maintenance	6,391	5,730	5,509
Total cost of sales	313,121	316,956	318,132
Gross profit	915,058	908,500	925,730
Operating expenses:
Sales and marketing	461,236	452,262	461,845
Research and development	235,706	225,131	227,433
General and administrative	98,390	93,935	91,265
Total operating expenses	795,332	771,328	780,543
Operating income	119,726	137,172	145,187
Other income (expense):
Interest income	1,122	1,403	1,133
Net foreign exchange loss	(4,632)	(7,075)	(2,250)
Other expense, net	(1,581)	(221)	(69)
Income before income taxes	114,635	131,279	144,001
Provision for income taxes	31,901	36,017	17,668
Net income	$ 82,734	$ 95,262	$ 126,333
Basic earnings per share	$ 0.64	$ 0.74	$ 0.99
Weighted average shares outstanding - basic	128,453	127,997	127,030
Diluted earnings per share	$ 0.64	$ 0.74	$ 0.99
Weighted average shares outstanding - diluted	129,008	128,668	127,799
Dividends declared per share	$ 0.80	$ 0.76	$ 0.60