UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue
Total revenue	[1]	$ 196,779	$ 186,596	$ 431,961	$ 442,905
Cost of revenue
Total cost of revenue	[1]	73,817	67,875	149,431	135,965
Gross profit	[1]	122,962	118,721	282,530	306,940
Operating expenses
Selling and marketing	[1]	93,972	75,200	182,355	144,881
Research and development	[1]	41,972	39,762	88,757	80,058
General and administrative	[1]	10,181	12,706	26,645	25,041
Total operating expenses	[1]	146,125	127,668	297,757	249,980
(Loss)/income from operations	[1]	(23,163)	(8,947)	(15,227)	56,960
Foreign currency transaction gain/(loss)	[1]	1,244	(2,242)	159	(1,497)
Interest income, net	[1]	629	202	1,393	407
Other income, net	[1]		566	363	287
(Loss)/income before (benefit) from income taxes	[1]	(21,290)	(10,421)	(13,312)	56,157
(Benefit) from income taxes	[1]	(10,881)	(14,123)	(15,103)	(508)
Net (loss)/income	[1]	$ (10,409)	$ 3,702	$ 1,791	$ 56,665
(Loss)/earnings per share
Basic	[1]	$ (0.13)	$ 0.05	$ 0.02	$ 0.74
Diluted	[1]	$ (0.13)	$ 0.04	$ 0.02	$ 0.69
Weighted-average number of common shares outstanding
Basic	[1]	78,635	77,313	78,436	77,039
Diluted	[1]	78,635	82,945	83,247	82,412
Cash dividends declared per share	[1]	$ 0.03	$ 0.03	$ 0.06	$ 0.06
Software license
Revenue
Total revenue	[1]	$ 44,784	$ 51,150	$ 132,557	$ 178,158
Cost of revenue
Total cost of revenue	[1]	1,262	1,250	2,517	2,550
Maintenance
Revenue
Total revenue	[1]	65,906	59,424	130,431	118,137
Cost of revenue
Total cost of revenue	[1]	5,874	7,011	11,956	14,229
Services
Revenue
Total revenue	[1]	86,089	76,022	168,973	146,610
Cost of revenue
Total cost of revenue	[1]	$ 66,681	$ 59,614	$ 134,958	$ 119,186

[1] On January 1, 2018 the Company adopted the ASC 606 revenue recognition standard and has adjusted prior periods to conform. See Note 2. "New Accounting Pronouncements" for additional information.