Recent Accounting Standards - Line Items Adjusted in Consolidated Statement of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenues	$ 133,531		$ 119,693		$ 117,737		$ 115,366		$ 131,917		$ 122,152		$ 120,602		$ 122,967		$ 486,327		$ 497,638		$ 503,843
Sales and marketing expenses																	191,235		205,525		175,045
Provision for income taxes																	3,908		(2,019)		53,279
Net income	$ 12,167		$ 9,700		$ 20,394		$ (7,906)		$ 3,301		$ 12,699		$ 4,828		$ 1,673		$ 34,355		$ 22,501		$ 18,195
Diluted earnings per share	$ 1.18	[1]	$ 0.94	[1]	$ 1.98	[1]	$ (0.77)	[1]	$ 0.30	[1]	$ 1.10	[1]	$ 0.42	[1]	$ 0.15	[1]	$ 3.33	[1],[2]	$ 1.97	[1],[2]	$ 1.58	[2]
As Reported | ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Sales and marketing expenses																					$ 174,612
Provision for income taxes																					54,964
Net income																					$ 17,643
Diluted earnings per share																					$ 1.53
Effect of the Adoption | ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Sales and marketing expenses																					$ 433
Provision for income taxes																					(1,685)
Net income																					$ 552
Diluted earnings per share																					$ 0.05
Product licenses
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenues																	$ 87,471		$ 88,057		$ 93,259
Product licenses | As Reported | ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenues																					93,969
Product licenses | Effect of the Adoption | ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenues																					(710)
Product support
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenues																	$ 292,035		$ 296,216		289,184
Product support | As Reported | ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenues																					289,174
Product support | Effect of the Adoption | ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenues																					$ 10

[1] The sum of the basic and diluted earnings (loss) per share for the four quarters may differ from annual earnings per share as the weighted average shares outstanding are computed independently for each of the quarters presented.

[2] Basic and fully diluted earnings per share for class A and class B common stock are the same.