Reclassified Amounts in Condensed Consolidated Statement of Operations (Detail) (USD $) In Thousands	3 Months Ended				6 Months Ended
	Jul. 31, 2011	Apr. 30, 2011	Jul. 31, 2010	Apr. 30, 2010	Jul. 31, 2011	Jul. 31, 2010
Revenues	$ 213,740	$ 230,035	$ 187,934	$ 180,577	$ 443,775	$ 368,511
Cost of revenues
System and software	14,294	16,077	7,977	6,643	30,371	14,620
Service and support	26,844	25,211	23,633	23,167	52,055	46,800
Amortization of purchased technology	2,754	3,357	3,560	3,569	6,111	7,129
Total cost of revenues	43,892	44,645	35,170	33,379	88,537	68,549
Gross margin	169,848	185,390	152,764	147,198	355,238	299,962
Operating expenses:
Research and development	69,905	69,368	67,792	66,644	139,273	134,436
Marketing and selling	75,758	77,924	72,720	71,824	153,682	144,544
General and administration	17,348	16,785	18,763	18,279	34,133	37,042
Equity in earnings of Frontline	(1,139)	(1,017)	(1,162)	(184)	(2,156)	(1,346)
Amortization of intangible assets	1,455	1,610	1,936	2,361	3,065	4,297
Special charges	1,677	4,547	3,206	3,268	6,224	6,474
Total operating expenses	165,004	169,217	163,255	162,192	334,221	325,447
Operating income (loss)	4,844	16,173	(10,491)	(14,994)	21,017	(25,485)
As Originally Reported
Revenues		230,035	187,934	180,577		368,511
Cost of revenues
System and software		13,016	5,237	3,954		9,191
Service and support		24,166	22,746	22,320		45,066
Amortization of purchased technology		3,357	3,560	3,569		7,129
Total cost of revenues		40,539	31,543	29,843		61,386
Gross margin		189,496	156,391	150,734		307,125
Operating expenses:
Research and development		69,906	65,045	64,132		129,177
Marketing and selling		76,404	74,634	73,652		148,286
General and administration		21,873	23,223	22,499		45,722
Equity in earnings of Frontline		(1,017)	(1,162)	(184)		(1,346)
Amortization of intangible assets		1,610	1,936	2,361		4,297
Special charges		4,547	3,206	3,268		6,474
Total operating expenses		173,323	166,882	165,728		332,610
Operating income (loss)		$ 16,173	$ (10,491)	$ (14,994)		$ (25,485)