Segment Information - Additional Information (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
Segment Reporting Information [Line Items]
Revenues	$ 135,037	$ 112,149	$ 113,366	$ 104,543	$ 141,241	$ 97,017	$ 92,423	$ 87,743	$ 465,095	$ 418,424	$ 405,755
Geographic Concentration Risk
Segment Reporting Information [Line Items]
Percentage of revenues									No country outside of the United States accounted for more than 10% of the Company’s consolidated revenues during the years ended December 31, 2011, 2010 and 2009.	No country outside of the United States accounted for more than 10% of the Company’s consolidated revenues during the years ended December 31, 2011, 2010 and 2009.	No country outside of the United States accounted for more than 10% of the Company’s consolidated revenues during the years ended December 31, 2011, 2010 and 2009.
Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage of revenues									No single customer accounted for more than 10% of the Company's consolidated revenues during the years ended December 31, 2011.	No single customer accounted for more than 10% of the Company's consolidated revenues during the years ended December 31, 2010.	No single customer accounted for more than 10% of the Company's consolidated revenues during the years ended December 31, 2009.
Americas - United States
Segment Reporting Information [Line Items]
Revenues									$ 188,000	$ 163,100	$ 172,700
BASE24
Segment Reporting Information [Line Items]
Percentage of total revenues from licensing BASE24 product line									43.00%	46.00%	46.00%