Revenues in Condensed Consolidated Statements of Operations from Arrangements for which Vendor-Specific Objective Evidence of Fair Value Does Not Exist for Each Undelivered Element (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue Recognition, Milestone Method [Line Items]
License	$ 94,230	$ 50,237	$ 67,161	$ 39,577	$ 80,425	$ 57,653	$ 61,377	$ 35,702	$ 251,205	$ 235,157	$ 233,931
Maintenance	63,000	59,262	60,141	59,492	67,421	63,764	62,309	62,499	241,895	255,993	245,954
Services	34,371	25,842	23,110	23,497	29,811	28,194	24,991	22,588	106,820	105,584	122,085
Total revenues	$ 308,637	$ 238,701	$ 265,822	$ 232,817	$ 290,224	$ 249,644	$ 254,808	$ 221,473	1,045,977	1,016,149	864,928
Vendor Specific Objective Evidence of Fair Value [Member]
Revenue Recognition, Milestone Method [Line Items]
License									7,797	22,211	22,190
Maintenance									3,801	7,699	9,649
Services									321	13	10
Total revenues									$ 11,919	$ 29,923	$ 31,849