Deferred Revenue and Advance Payments (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Deferred Revenue Disclosure [Abstract]
Deferred product licenses revenue, Current	$ 2,315	$ 1,495
Deferred subscription services revenue, Current	23,089	26,258
Deferred product support revenue, Current	130,339	156,216
Deferred other services revenue, Current	4,954	7,281
Total current deferred revenue and advance payments	160,697	191,250
Deferred product licenses revenue, Non-current	74	139
Deferred subscription services revenue, Non-current	590	8,758
Deferred product support revenue, Non-current	6,973	5,055
Deferred other services revenue, Non-current	665	710
Total non-current deferred revenue and advance payments	$ 8,302	$ 14,662