Revenues in Consolidated Statements of Income from Arrangements for which VSOE of Fair Value Does Not Exist (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenue Recognition, Milestone Method [Line Items]
Software license fees	$ 60,762	$ 39,249	$ 46,085	$ 43,724	$ 66,039	$ 37,804	$ 31,399	$ 29,317	$ 189,820	$ 164,559	$ 154,517
Maintenance fees	39,164	36,928	37,195	35,070	35,414	32,480	34,207	33,422	148,357	135,523	130,922
Services	21,956	23,770	18,673	15,371	26,745	15,439	17,187	14,618	79,770	73,989	80,146
Total revenues	135,037	112,149	113,366	104,543	141,241	97,017	92,423	87,743	465,095	418,424	405,755
Vendor Specific Objective Evidence of Fair Value
Revenue Recognition, Milestone Method [Line Items]
Software license fees									66,939	47,095	13,905
Maintenance fees									16,801	10,261	5,273
Services									1,362	4,118	6,513
Total revenues									$ 85,102	$ 61,474	$ 25,691