Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net sales:
Total net sales	$ 1,353,215	$ 1,359,132	$ 1,289,386
Cost of sales:
Total cost of sales	336,891	333,727	328,324
Gross profit	1,016,324	1,025,405	961,062
Operating expenses:
Sales and marketing	473,392	482,576	477,921
Research and development	272,452	261,072	231,761
General and administrative	122,768	108,878	105,602
Gain on sale of assets	(26,842)	0	0
Total operating expenses	841,770	852,526	815,284
Operating income	174,554	172,879	145,778
Other income (expense):
Interest income	8,129	5,896	2,276
Net foreign exchange (loss) gain	(1,846)	(3,423)	892
Other (expense) income, net	(293)	1,101	(1,566)
Income before income taxes	180,544	176,453	147,380
Provision for income taxes	18,393	21,396	94,969
Net income	$ 162,151	$ 155,057	$ 52,411
Basic earnings per share (in dollars per share)	$ 1.23	$ 1.17	$ 0.40
Weighted average shares outstanding - basic (in shares)	131,722	131,987	130,300
Diluted earnings per share (in dollars per share)	$ 1.22	$ 1.16	$ 0.40
Weighted average shares outstanding - diluted (in shares)	132,734	133,274	131,387
Dividends declared per share (in dollars per share)	$ 1.00	$ 0.92	$ 0.84
Product
Net sales:
Total net sales	$ 1,215,014	$ 1,220,027	$ 1,173,476
Cost of sales:
Total cost of sales	329,364	325,208	318,863
Software maintenance
Net sales:
Total net sales	138,201	139,105	115,910
Cost of sales:
Total cost of sales	$ 7,527	$ 8,519	$ 9,461