CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Software licenses	$ 624,964	$ 568,174	$ 555,105
Maintenance and service	470,286	420,291	387,648
Total revenue	1,095,250	988,465	942,753
Cost of sales:
Software licenses	34,421	28,860	29,105
Amortization	36,794	38,092	38,755
Maintenance and service	78,949	79,908	79,386
Total cost of sales	150,164	146,860	147,246
Gross profit	945,086	841,605	795,507
Operating expenses:
Selling, general and administrative	338,640	269,515	253,603
Research and development	202,746	183,093	168,831
Amortization	12,972	12,755	19,394
Total operating expenses	554,358	465,363	441,828
Operating income	390,728	376,242	353,679
Interest income	6,962	4,209	2,829
Other (expense) income, net	(1,996)	(136)	257
Income before income tax provision	395,694	380,315	356,765
Income tax provision	136,443	114,679	104,244
Net income	$ 259,251	$ 265,636	$ 252,521
Earnings per share – basic:
Earnings per share	$ 3.05	$ 3.05	$ 2.82
Weighted average shares	84,988	87,227	89,561
Earnings per share – diluted:
Earnings per share	$ 2.98	$ 2.99	$ 2.76
Weighted average shares	86,854	88,969	91,502