CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue:
Software licenses	$ 555,105	$ 564,502	$ 528,944
Maintenance and service	387,648	371,519	332,316
Total revenue	942,753	936,021	861,260
Cost of sales:
Software licenses	29,105	30,607	28,363
Amortization	38,755	37,653	38,298
Maintenance and service	79,386	85,126	80,031
Total cost of sales	147,246	153,386	146,692
Gross profit	795,507	782,635	714,568
Operating expenses:
Selling, general and administrative	253,603	246,376	218,907
Research and development	168,831	165,421	151,439
Amortization	19,394	23,388	22,359
Total operating expenses	441,828	435,185	392,705
Operating income	353,679	347,450	321,863
Interest expense	(325)	(779)	(1,169)
Interest income	2,829	3,002	2,841
Other income (expense), net	582	(1,534)	(1,046)
Income before income tax provision	356,765	348,139	322,489
Income tax provision	104,244	93,449	77,162
Net income	$ 252,521	$ 254,690	$ 245,327
Earnings per share – basic:
Basic earnings per share (in USD per share)	$ 2.82	$ 2.77	$ 2.65
Weighted average shares - basic	89,561	92,067	92,691
Earnings per share – diluted:
Diluted earnings per share (in USD per share)	$ 2.76	$ 2.70	$ 2.58
Weighted average shares - diluted	91,502	94,194	95,139