Revenues in Consolidated Statements of Income from Arrangements for which Vendor-Specific Objective Evidence of Fair Value Does Not Exist for Each Undelivered Element (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenue Recognition, Milestone Method [Line Items]
Software license fees	$ 94,731	$ 39,560	$ 36,645	$ 50,910	$ 60,762	$ 39,249	$ 46,085	$ 43,724	$ 221,846	$ 189,820	$ 164,559
Maintenance fees	58,862	47,920	49,359	43,735	39,164	36,928	37,195	35,070	199,876	148,357	135,523
Services	38,985	35,811	33,888	22,852	21,956	23,770	18,673	15,371	131,536	79,770	73,989
Total revenues	224,095	155,062	149,797	137,625	135,037	112,149	113,366	104,543	666,579	465,095	418,424
Vendor Specific Objective Evidence of Fair Value
Revenue Recognition, Milestone Method [Line Items]
Software license fees									38,226	66,939	47,095
Maintenance fees									14,178	16,801	10,261
Services									830	1,362	4,118
Total revenues									$ 53,234	$ 85,102	$ 61,474